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Earth’s Crust Test Prep According to the plate tectonics theory, the Peru-Chile Trench and the Andes Mountains formed along the west coast of South America because the South American Plate 1 collided with the Nazca Plate 2 collided with the North American Plate 3 slid away from the Nazca Plate 4 slid away from the North American Plate Base your answers to the following two questions on the cross section below, which shows a portion of Earth’s crust and upper mantle near a mid-ocean ridge. If the crust symbol represents basalt with normal magnetic polarity, what does the crust symbol most likely represent? 1 igneous rock with normal magnetic polarity 2 igneous rock with reversed magnetic polarity 3 sedimentary rock with normal magnetic polarity 4 sedimentary rock with reversed magnetic polarity The geological features of the ocean floor in this region resulted from 1 colliding plates in the lithosphere 2 sinking iron and magnesium in the lithosphere 3 cooler temperatures in the mantle 4 rising convection currents in the mantle Base your answers to the following two questions on the diagram below, which represents seismic stations A, B, and C. The distance from each station to an earthquake’s epicenter is plotted. The P-wave of an earthquake originating 2,600 kilometers from seismic station A arrived at 5:24:45 a.m. What was the arrival time of the S-wave from the same earthquake? (1) 1:24:45 a.m. (2) 5:21:05 a.m. (3) 5:28:45 a.m. (4) 9:24:05 a.m. The epicenter is closest to point (1) D (2) E (3) F (4) G Which landscape region probably resulted from the erosion of faulted rock layers? Base your answers to the following question using the Earth Science Reference Tables, the map below, and your knowledge of Earth science. Letters A through F are locations on Earth’s surface. Which location is closest to a divergent plate boundary at an oceanic ridge? (1) A (2) B (3) C (4) E Base your answers to the following 5 questions on the Earth Science Reference Tables, the map below, and your knowledge of Earth science. The map shows part of the earthquake damage field that resulted from the earthquake that occurred in Northridge, in southern California, in January 1994. Several sites associated with the earthquake and earthquake damage are shown. Which surface location had the least damage? (1) R (2) B (3) E (4) F This earthquake provides evidence for the existence of 1 Earth’s solid outer core 2 convection cells in Earth’s outer core 3 faulting of bedrock at Northridge 4 magnetic field reversals at Northridge Which information would have been most useful for locating the earthquake epicenter? 1 the difference between the arrival times of the P-wave and the S-wave 2 the arrival time of the S-wave 3 the velocity of the P-wave 4 the location of damage from the earthquake The greatest surface damage occurred in zone IX because 1 the regional seismograph stations were closest to zone IX 2 of local conditions at zone IX 3 zone IX was reached first by earthquake waves 4 zone IX was at the epicenter of the earthquake Which crustal plate boundary is most closely associated with this earthquake? 1 Cocos Plate — Pacific Plate 2 Cocos Plate — Nazca Plate 3 North American Plate — Nazca Plate 4 North American Plate — Pacific Plate Which statement most accurately compares Earth’s crust and Earth’s mantle? 1 The crust is thinner and less dense than the mantle. 2 The crust is thinner and more dense than the mantle. 3 The crust is thicker and less dense than the mantle. 4 The crust is thicker and more dense than the mantle. Based on the theory of plate tectonics, it is inferred that over the past 250 million years North America has moved toward the (1) northwest (2) southwest (3) southeast (4) northeast According to tectonic plate maps, New York State is presently located (1) at a convergent plate boundary (2) above a mantle hot spot (3) above a mid-ocean ridge (4) near the center of a large plate Base your answers to the following two questions on the cross-sectional view of Earth below, which shows seismic waves traveling from the focus of an earthquake. Points A and B are locations on Earth’s surface. Which statement best explains why only one type of seismic wave was recorded at location B? (1) S-waves cannot travel through the liquid outer core. (2) S-waves cannot travel through the liquid inner core. (3) P-waves cannot travel through the solid outer core. (4) P-waves cannot travel through the solid inner core. A seismic station located at point A is 5400 kilometers away from the epicenter of the earthquake. If the arrival time for the P-wave at point A was 2:00 p.m., the arrival time for the S-wave at point A was approximately (1) 1:53 p.m. (2) 2:07 p.m. (3) 2:09 p.m. (4) 2:16 p.m. The cross section below shows a drill rig used to collect rock samples from below Earth’s surface. The rock samples collected from the bottom of the drill hole came from which Earth layer? (1) lithosphere (2) hydrosphere (3) asthenosphere (4) stiffer mantle Base your answers to the following 4 questions on the world map below and on your knowledge of Earth science. The map shows major earthquakes and volcanic activity occurring from 1996 through 2000. Letter A represents a volcano on a crustal plate boundary. On the map above, place an X on the map to show the location of the Nazca Plate. Explain why most major earthquakes are found in specific zones instead of being randomly scattered across Earth’s surface. _______________________________________________________________________ _______________________________________________________________________ Identify the source of the magma for the volcanic activity in Hawaii. _______________________________________________________________________ _______________________________________________________________________ Identify the type of plate movement responsible for the presence of the volcano at location A. _______________________________________________________________________ In which Earth layer are most convection currents that cause seafloor spreading thought to be located? (1) crust (2) asthenosphere (3) outer core (4) inner core An earthquake’s magnitude can be determined by (1) analyzing the seismic waves recorded by a seismograph (2) calculating the depth of the earthquake faulting (3) calculating the time the earthquake occurred (4) comparing the speed of P-waves and S-waves A seismic station is recording the seismic waves produced by an earthquake that occurred 4200 kilometers away. Approximately how long after the arrival of the first P-wave will the first S-wave arrive? (1) 1 min 05 sec (2) 5 min 50 sec (3) 7 min 20 sec (4) 13 min 10 sec Which graph best shows the inferred density of Earth’s interior as depth increases from the upper mantle to the lower mantle? The block diagram below shows a tectonic plate boundary. Points A and B represent locations on Earth’s surface. Which graph best shows the depths of most major earthquakes whose epicenters lie between A and B? Base your answers to the following 3 questions on the map below. The ▲ represents Mt. Hekla, a volcano in Iceland. The isolines represent the thickness of ash, in centimeters, that settled on Earth’s surface after a volcanic eruption of Mt. Hekla on March 29, 1947. Point X is a location on the surface of the ash. At the time of the eruption, the wind direction was primarily from the (1) east (2) west (3) north (4) south How many centimeters thick was the ash beneath point X? (1) 0 (2) 15 (3) 20 (4) 25 In addition to the ash, solid rock formed on Mt. Hekla from the lava extruded during this eruption. This rock is most likely (1) light-colored metamorphic (2) dark-colored metamorphic (3) fine-grained igneous (4) coarse-grained igneous Base your answers to the following 4 questions on the map and block diagram below. The map shows the location of North Island in New Zealand. The block diagram shows a portion of North Island. The Hikurangi Trench is shown forming at the edge of the Pacific Plate. Point X is at the boundary between the lithosphere and the asthenosphere. State the approximate temperature at point X. _____________________________________________________________________________________ On what tectonic plate are both North Island and White Island located? ____________________________________________________________________________________ Describe the type of tectonic plate motion that formed the Hikurangi Trench. ___________________________________________________________________________________ Describe one action that people on North Island should take if a tsunami warning is issued. ___________________________________________________________________________________ A seismic station recorded the arrival of a P-wave at 10:00:00 a.m. The S-wave arrival was recorded at 10:04:20 a.m. What is the approximate distance between the earthquake epicenter and the seismic station? (1) 1.1 x 103 km (2) 2.2 x 103 km (3) 2.9 x 103 km (4) 7.2 x 103 km Through which materials can P-waves travel? 1 solid rock, only 2 magma and water, only 3 magma, water, and natural gas, only 4 solid rock, magma, water, and natural gas Which observed feature would provide the best evidence of crustal stability? 1 horizontal sedimentary layers 2 changed benchmark elevations 3 folded, faulted, and tilted rock strata 4 marine fossils at elevations high above sea level Which cross-sectional diagram of a portion of the crust and mantle best shows the pattern of mantle convection currents that are believed to cause the formation of a mid-ocean ridge? The diagram below shows a cross section of a portion of Earth’s crust. Altitude is shown in meters above sea level. This landscape region is best classified as an eroded 1 plain 2 plateau 3 domed mountain 4 folded lowland Base your answers to the following 5 questions on the Earth Science Reference Tables, the diagram below, and your knowledge of Earth science. The diagram represents Earth’s interior zones. The thinnest section of Earth’s crust is found beneath 1 oceans 2 desert regions 3 coastal plains 4 mountain regions In which layer of Earth’s interior is the inferred temperature 6,000°C? 1 crust 2 mantle 3 outer core 4 inner core Scientists have classified Earth’s interior into the zones shown based primarily on evidence gained by studying 1 deep drill cores 2 volcanic eruptions 3 gravity measurements 4 earthquake seismic waves The composition of Earth’s core is thought to be the same as the composition of many 1 meteorites 2 volcanic ashes 3 granites 4 basalts Which graph best represents the relationship between depth below Earth’s surface and density? The diagram below shows the interaction of two tectonic plates. The type of plate boundary represented in the diagram most likely exists between the (1) Antarctic Plate and the African Plate (2) Antarctic Plate and the Indian-Australian Plate (3) South American Plate and the Nazca Plate (4) South American Plate and the African Plate Base your answers to the following 4 questions on the map below and on your knowledge of Earth science. The map shows the location of the epicenter, X , of an earthquake that occurred on April 20, 2002, about 29 kilometers southwest of Plattsburgh, New York. State the latitude and longitude of this earthquake epicenter. Express your answers to the nearest tenth of a degree and include the compass directions. _____________________________________________________________________________________ What is the minimum number of seismographic stations needed to locate the epicenter of an earthquake? _____________________________________________________________________________________ Explain why this earthquake was most likely felt with greater intensity by people in Peru, New York, than by people in Lake Placid, New York. _____________________________________________________________________________________ _____________________________________________________________________________________ A seismic station located 1,800 kilometers from the epicenter recorded the P-wave and S-wave arrival times or this earthquake. What was the difference in the arrival time of the first P-wave and the first S-wave? _____________________________________________________________________________________ Base your answers to the following 4 questions on the world map shown below and on your knowledge of Earth science. Letters A through H represent locations on Earth’s surface. Explain why most earthquakes that occur in the crust beneath location B are shallower than most earthquakes that occur in the crust beneath location C. _______________________________________________________________________________________ _______________________________________________________________________________________ Explain why location A has a greater probability of experiencing a major earthquake than location D. _______________________________________________________________________________________ _______________________________________________________________________________________ Explain why a volcanic eruption is more likely to occur at location E than at location F. _______________________________________________________________________________________ _______________________________________________________________________________________ Explain why the geologic age of the oceanic bedrock increases from location G to location H. _______________________________________________________________________________________ _______________________________________________________________________________________ Which coastal area is most likely to experience a severe earthquake? (1) east coast of North America (2) east coast of Australia (3) west coast of Africa (4) west coast of South America A seismic station 4000 kilometers from the epicenter of an earthquake records the arrival time of the first Pwave at 10:00:00. At what time did the first S-wave arrive at this station? (1) 9:55:00 (2) 10:05:40 (3) 10:07:05 (4) 10:12:40 Which statement correctly describes the density of Earth’s mantle compared to the density of Earth’s core and crust? (1) The mantle is less dense than the core but more dense than the crust. (2) The mantle is less dense than both the core and the crust. (3) The mantle is more dense than the core but less dense than the crust. (4) The mantle is more dense than both the core and the crust. Convection currents in the plastic mantle are believed to cause divergence of lithospheric plates at the (1) Peru-Chile Trench (2) Mariana Trench (3) Canary Islands Hot Spot (4) Iceland Hot Spot Arrows in the block diagram below show the relative movement along a tectonic plate boundary. Between which two tectonic plates does this type of plate boundary exist? (1) Nazca Plate and South American Plate (2) Eurasian Plate and Indian-Australian Plate (3) North American Plate and Eurasian Plate (4) Pacific Plate and North American Plate Base your answers to the following 3 questions on the passage below and on your knowledge of Earth science. A New Oregon Volcano? The Three Sisters are 10,000-foot volcanic mountain peaks in Oregon. Volcanic eruptions began building the Three Sisters from andesitic lava and cinders 700,000 years ago. The last major eruption occurred 2000 years ago. West of the Three Sisters peaks, geologists have recently discovered that Earth’s surface is bulging upward in a bull’s-eye pattern 10 miles wide. There is a 4-inch rise at its center, which geologists believe could be the beginning of another volcano. The uplift was found by comparing satellite images. This uplift in Oregon may allow the tracking of a volcanic eruption from its beginning, long before the smoke and explosions begin. This uplift is most likely caused by an upflow of molten rock from more than four miles below the surface. Rock melts within Earth’s interior and then moves upward in cracks in Earth’s crust, where it forms large underground pools called magma chambers. Magma upwelling often produces signs that help scientists predict eruptions and protect humans. When the pressure of rising magma becomes forceful enough to crack bedrock, swarms of small earthquakes occur. Rising magma releases carbon dioxide and other gases that can be detected at the surface. Identify one of the minerals found in the andesite rock of the Three Sisters volcanoes. _______________________________________________________________________________________ The cross section below represents Earth’s interior beneath the Three Sisters. Place a triangle, ▲, on the cross section to indicate the location where the new volcano will most likely form. On the same cross section above, place arrows through each point, X, Y, and Z, to indicate the relative motion of each of these sections of the lithosphere. The photograph below represents a mountainous area in the Pacific Northwest. Scientists believe that sedimentary rocks like those represent evidence of crustal change because these rocks were 1 formed by igneous intrusion 2 faulted during deposition 3 originally deposited in horizontal layers 4 changed from metamorphic rocks How far from an earthquake epicenter is a city where the difference between the P-wave and S-wave arrival times is 6 minutes and 20 seconds? (1) 1.7 x 103 km (2) 9.9 x 103 km (3) 3.5 x 103 km (4) 4.7 x 103 km The photograph below shows a large crater located in the southwestern United States. Some fragments taken from the site have a nickel-iron composition. This evidence indicates that the crater probably was formed by 1 the impact of a meteorite from space 2 the collapse of a cavern roof 3 an eruption of a volcano 4 an underwater explosion of steam Which map best represents the general pattern of magnetism in the oceanic bedrock near the mid-Atlantic Ridge? Which features are commonly formed at the plate boundaries where continental crust converges with oceanic crust? 1 large volcanic mountain ranges parallel to the coast at the center of the continents 2 a deep ocean trench and a continental volcanic mountain range near the coast 3 an underwater volcanic mountain range and rift valley on the ocean ridge near the coast 4 long chains of mid-ocean volcanic islands perpendicular to the coast Base your answers to the following 3 questions on the map below, which shows an area of the northwestern United States affected by a major volcanic eruption at Crater Lake during the Holocene Epoch. The pattern of distribution of the ash from the volcano was most likely caused by the direction of the 1 magnetic field 2 force of the volcanic eruption 3 flow of surface water 4 atmospheric air movements The age of this volcanic eruption was most accurately determined to be Holocene by measuring the radioactive 1 potassium in the fine-grained volcanic rock 2 carbon in trees buried by the ash 3 uranium in the volcanic ash 4 rubidium in the igneous glass This volcanic eruption is most useful to scientists today as a relative time marker in the geologic record of this map region because the 1 lava cooled quickly at the surface 2 lava contained radioactive rubidium-87 3 volcanic ash spread quickly over a large area 4 volcanic ash fell to Earth more quickly near the volcano than far from the volcano Base your answers to the following 5 questions on the Earth Science Reference Tables, the map below, and your knowledge of Earth science. The map shows a portion of California along the San Andreas Fault zone. The map shows the probability (percentage chance) that an earthquake strong enough to damage buildings and other structures will occur between now and the year 2024. Which city has the greatest danger of damage from an earthquake? 1 Barstow 2 Parkfield 3 Oceanside 4 San Bernardino This fault zone is located along the boundary between which two crustal plates? 1 Cocos plate and Pacific plate 2 North American plate and Pacific plate 3 Nazca plate and Cocos plate 4 North American plate and South American plate If a large earthquake were to occur at San Diego, the earliest indication at another California location of the occurrence of that earthquake would be the arrival of the (1) S-waves at Oceanside (2) S-waves at San Bernardino (3) P-waves at Oceanside (4) P-waves at San Bernardino Which diagram best represents the relative movements of the crustal plates along the San Andreas Fault in the map area? Which map best represents the location of the primary San Andreas Fault line? The drawing below shows the effects of an earthquake on a small part of Earth’s surface. Letters A and B indicate land on opposite sides of a cliff that formed along a fault during the earthquake. In relation to the position of side B, the movement of side A was 1 eastward and downward 2 eastward and upward 3 westward and downward 4 westward and upward A student set up the activity shown in the diagram below to demonstrate how convection cells in Earth’s mantle could cause crustal plates to converge. Which diagram shows the bet placement of heat sources to cause the blocks to converge? A seismograph records the arrival of a P-wave at 11:13 a.m. If the earthquake occurred 4,000 kilometers from the recording station, when did the earthquake occur? (1) 11:06 a.m. (2) 11:11 a.m. (3) 11:13 a.m. (4) 11:20 a.m. At which depth below Earth’s surface is the density most likely 9.5 grams per cubic centimeter? (1) 1,500 km (2) 2,000 km (3) 3,500 km (4) 6,000 km The block diagram below represents a portion of the surface of Earth’s crust. Which letter is located on the boundary between two landscape regions? (1) A (2) B (3) C (4) D What happens to P-waves and S-waves from a crustal earthquake when the waves reach Earth’s outer core? (1) S-waves are transmitted through the outer core, but P-waves are not transmitted. (2) P-waves are transmitted through the outer core, but S-waves are not transmitted. (3) Both P-waves and S-waves are transmitted through the outer core. (4) Neither P-waves nor S-waves are transmitted through the outer core. Base your answers to the following five questions on the Earth Science Reference Tables, the map below, and your knowledge of Earth science. The map shows the island of Hawaii (approximately 20° N 157° W) and the locations of recent volcanic eruptions and earthquake epicenters. The volcanic eruptions are inferred to be caused by the movement of the lithospheric plate over a hot spot in the mantle below. Where are earthquakes on and around Hawaii located? 1 along shorelines, only 2 in the ocean, only 3 in older rocks, only 4 scattered across the area Rock collected from the side of Kilauea Volcano has the following mineral composition: 5% plagioclase feldspar, 68% pyroxene, 25% olivine, and 2% hornblende. What type of rock is this? 1 andesite 2 scoria 3 rhyolite 4 peridotite Which inference concerning the distribution of earthquakes and recent volcanic eruptions on this island is most accurate? 1 Earthquakes and recent volcanic eruptions are located mainly along the boundary between the older rocks and the younger rocks. 2 Recent volcanic eruptions are more common than earthquakes. 3 Many earthquakes occur near recent volcanic eruptions. 4 Earthquakes and recent volcanic eruptions rarely occur in the same areas. A scientist wants to film underwater volcanic activity that is forming a new island in the Hawaiian Island chain. In which direction from Hawaii should she concentrate her efforts? 1 northeast 2 northwest 3 southeast 4 southwest Hawaii is located near the middle of which tectonic plate? 1 Philippine plate 2 Nazca plate 3 North American plate 4 Pacific plate What is the primary method of heat transfer through solid rock during contact metamorphism? 1 advection 2 convection 3 absorption 4 conduction Base your answers to the following five questions on the Earth Science Reference Tables, the map and table of the Modified Mercalli Scale below, and your knowledge of Earth science. The map shows the intensities of the earthquake that occurred slightly southwest of New Madrid, Missouri, on December 16, 1811. The numbered areas on the map were determined from the Modified Mercalli Scale according to the observed effects of the earthquake. What is the approximate location of the earthquake’s epicenter? (1) 36° N, 90° W (2) 90° N, 36° W (3) 36° N, 90° E (4) 90° N, 36° E What was the approximate travel time for the earthquake’s P-wave from the epicenter to Syracuse, New York? (1) 1 min (2) 5 min (3) 3 min (4) 10 min Which city would have issued the report: “Heavy furniture moved, everyone felt the earthquake, and many people were frightened and ran outdoors”? 1 Cincinnati 2 Pittsburgh 3 Syracuse 4 Boston Which statement best describes the earthquake waves recorded at Louisville? (1) S-waves arrived ahead of P-waves. (2) P-waves arrived ahead of S-waves. (3) S-waves arrived but P-waves did not arrive. (4) Neither S-waves nor P-waves arrived. For which city was the difference in arrival times between P-waves and S-waves greatest? 1 Nashville 2 Pittsburgh 3 Syracuse 4 Boston The diagram below represents a geologic cross section of a portion of Earth’s crust. Folding and erosion occurred after the formation of the (1) Gayle shale (2) Freeport sandstone (3) Erie coal, but before formation of Freeport sandstone (4) Dunbar limestone, but before formation of Erie coal Beneath which surface location is Earth’s crust the thinnest? (1) East Pacific Ridge (2) the center of South America (3) Old Forge, New York (4) San Andreas Fault The graph below shows the different velocities of P-waves and S-waves through Earth’s interior. Which cross section best shows the inferred thickness of Earth’s interior layers that cause these different velocities? The diagram below represents the pattern of normal and reversed magnetic polarity and the relative age of the igneous bedrock composing the ocean floor on the east side of the Mid-Atlantic Ridge. The magnetic polarity of the bedrock on the west side of the ridge has been deliberately left blank. Which diagram best shows the magnetic pattern and relative age of the igneous bedrock on the west side of the ridge? Base your answers to the following four questions on the information, map, and cross section below. The map represents a portion of Earth’s surface in the Pacific Ocean. The positions of islands, earthquake epicenters, active volcanoes, and the Tonga Trench are shown. Lines of latitude and longitude have been included. The cross section shows earthquakes that occurred beneath line XY on the map. Depth beneath Earth’s surface is indicated by the scale along the left side of the cross section, as are the range of depths for shallow, intermediate, and deep earthquakes. Distance from the trench is indicated by the scale along the bottom of the cross section. The Tonga Trench is located at the tectonic boundary between the Pacific Plate and the (1) Antarctic Plate (2) Philippine Plate (3) Indian-Australian Plate (4) Nazca Plate The greatest number of earthquakes shown in the cross section occurred (1) at sea level (2) between sea level and a depth of 100 km (3) at a depth between 100 and 300 km (4) at a depth between 300 and 600 km Which cross section has arrows that best represent the relative motion of the crustal plates along the WadatiBenioff zone beneath the Tonga Trench? The latitude and longitude of the center of Vanau Leva is closest to (1) 17° N 179° W (2) 17° N 181° W (3) 17° S 179° E (4) 17° S 181° E Base your answers to the following two questions on the diagram below, which shows two seismogram tracings, at stations A and B, for the same earthquake. The arrival times of the P-waves and S-waves are indicated on each tracing. Explain how the seismic tracings recorded at station A and station B indicate that station A is farther from the earthquake epicenter than station B. _______________________________________________________________________________________ _______________________________________________________________________________________ _______________________________________________________________________________________ Seismic station A is located 5,400 kilometers from the epicenter of the earthquake. How much time would it take for the first S-wave produced by this earthquake to reach seismic station A? Base your answers to the following three questions on the passage below and on your knowledge of Earth science. Great Balls of Fire The Earth’s predicted near-miss with asteroid XF11 in the year 2028 has once again focused attention on the fear that a large asteroid or comet hitting our planet could trigger a global catastrophe. To back this up, every article and television program about XF11 boldly asserted that the dinosaur extinction was caused by a giant asteroid impacting into the Earth 65 million years ago. This has typically been accompanied by a picture of frightened dinosaurs looking skyward at a huge flaming meteorite streaking across the horizon. This scenario is so widely accepted that few commentators bother to question it any more. There is, however, much evidence to suggest that an asteroid may not have hit the Earth 65 million years ago and that, even if it did, it did not cause the mass extinction of life attributed to it. There is also the possibility that dinosaurs may not have been around to witness it! by Paul Chambers http://www.forteantimes.com/articles/111_asteroid.shtml (6/98) If an asteroid struck Earth 65 million years ago, what surface feature was most likely created by this asteroid impact? _______________________________________________________________________________________ _______________________________________________________________________________________ Identify one geologic process occurring on Earth that could have hidden or even destroyed this inferred impact feature. ______________________________________________________________________________________ ______________________________________________________________________________________ Explain how an asteroid impact may have been able to cause a worldwide mass extinction of dinosaurs. ______________________________________________________________________________________ ______________________________________________________________________________________ Great volcanic eruptions send dust and ash into the stratosphere. Weeks after such great eruptions, air temperatures are often (1) cooler than normal because the atmosphere is less transparent (2) cooler than normal because the atmosphere is more transparent (3) warmer than normal because the atmosphere is less transparent (4) warmer than normal because the atmosphere is more transparent A P-wave takes 8 minutes and 20 seconds to travel from the epicenter of an earthquake to a seismic station. Approximately how long will an S-wave take to travel from the epicenter of the same earthquake to this seismic station? (1) 6 min 40 sec (2) 9 min 40 sec (3) 15 min 00 sec (4) 19 min 00 sec The cross section below shows the direction of movement of an oceanic plate over a mantle hot spot, resulting in the formation of a chain of volcanoes labeled A, B, C, and D. The geologic age of volcano C is shown. What are the most likely geologic ages of volcanoes B and D? (1) B is 5 million years old and D is 12 million years old. (2) B is 2 million years old and D is 6 million years old. (3) B is 9 million years old and D is 9 million years old. (4) B is 10 million years old and D is 4 million years old. Base your answers to the following three questions on the cross section below and on your knowledge of Earth science. The cross section shows a portion of Earth’s interior. Layer X is part of Earth’s interior. Identify the texture and relative density of the granitic bedrock of the continental crust and the basaltic bedrock of the oceanic crust. The minerals biotite and amphibole may be found in igneous bedrock of both the oceanic crust and the continental crust. Identify two other minerals commonly found in the basaltic oceanic crust. Identify the part of Earth’s lithosphere represented by layer X. _______________________________________________________________________________________ Base your answers to the following three questions on the cross section below, which shows the major surface features of Earth along 25° S latitude between 75° W and 15° E longitude. Points A, B, and C represent locations on Earth’s crust. Identify the crustal feature located at point A. _____________________________________________________________________________________ Identify the tectonic plate motion that is causing an increase in the distance between South America and Africa. ______________________________________________________________________________________ Bedrock samples were taken at the mid-ocean ridge and points B and C. On the grid below, draw a line to show the relative age of the bedrock samples between these locations. The map below shows the location of an earthquake epicenter in New York State. Seismic stations A, B, and C received the data used to locate the earthquake epicenter. The seismogram recorded at station A would show the (1) arrival of P-waves, only (2) earliest arrival time of P-waves (3) greatest difference in the arrival times of P-waves and S-waves (4) arrival of S-waves before the arrival of P-waves An earthquake’s first P-wave arrives at a seismic station at 12:00:00. This P-wave has traveled 6000 kilometers from the epicenter. At what time will the first S-wave from the same earthquake arrive at the seismic station? (1) 11:52:20 (2) 12:07:40 (3) 12:09:20 (4) 12:17:00 The movement of tectonic plates is inferred by many scientists to be driven by (1) tidal motions in the hydrosphere (2) density differences in the troposphere (3) convection currents in the asthenosphere (4) solidification in the lithosphere Which two tectonic plates are separated by a mid-ocean ridge? (1) Indian-Australian and Eurasian (2) Indian-Australian and Pacific (3) North American and South American (4) North American and Eurasian Base your answers to the following two questions on the block diagram below. The diagram shows the tectonic plate boundary between Africa and North America 300 million years ago, as these two continents united into a single landmass. The arrows at letters A, B, C, and D represent relative crustal movements. Letter X shows the eruption of a volcano at that time. Identify the type of tectonic plate motion represented by the arrow shown at D. ______________________________________________________ Identify the type of tectonic motion represented by the arrows shown at A, B, and C. ______________________________________________________ The graph below shows the percent by mass of the elements of Earth’s crust. Each letter on the graph represents an element. Which elements are represented by the letters a and b, respectively? 1 aluminum and iron 2 calcium and nitrogen 3 potassium and sodium 4 oxygen and silicon Compared to the continental crust, the oceanic crust is 1 thicker 2 more dense 3 more granitic 4 more felsic An earthquake recorded by seismic stations around the world created the pattern of seismic wave recordings shown in the diagram below. Which statement best explains this pattern of wave recordings? (1) Some seismic waves cannot travel through oceans to reach every location on Earth. (2) S-waves are too weak to travel very far from the earthquake focus. (3) Mountain ranges and tectonic plate boundaries absorb or bend seismic waves. (4) Layers with different properties inside Earth absorb or bend seismic waves. The diagram below shows the collision of an oceanic plate and a continental plate. Collisions between oceanic plates and continental plates are thought to result primarily from 1 hot liquid magma in the inner core 2 convection currents in the mantle 3 volcanic eruptions along coastlines 4 meteor impacts in the ocean basins Which information indicates that new seafloor rock is forming along a mid-ocean ridge and then moving horizontally away from the ridge? 1 Most volcanoes are located under ocean water. 2 Seafloor rock is older than continental rock. 3 Fossils of marine organisms can be found at high elevations on continents. 4 The age of seafloor rock increases as the distance from the mid-ocean ridge increases. An earthquake shear wave generally travels faster as the wave moves deeper into Earth’s interior because greater depths have 1 less confining pressure 2 lower melting points 3 greater rock density 4 greater rock temperatures Base your answers to the following five questions on the Earth Science Reference Tables, the map and seismograms below, and your knowledge of Earth science. The map shows seismic stations in Chicago, Denver, Oklahoma City, and Tampa that record data from an earthquake. Seismograms A, B, C, and D show, in Greenwich time, the arrival times of the earthquake waves at the four stations. Which location on the map below is closest to the epicenter of this earthquake? (1) W (2) X (3) Y (4) Z Which seismogram was recorded at Tampa? 1 seismogram A 2 seismogram B 3 seismogram C 4 seismogram D What was the origin time of this earthquake? (1) 2:33:00 a.m. (2) 2:34:40 a.m. (3) 2:35:40 a.m. (4) 2:37:00 a.m. The P-wave generated by this earthquake took 2 minutes and 40 seconds to reach one of the seismic stations. Approximately how long did the S-wave take to reach the same seismic station? (1) 1 minute 20 seconds (2) 2 minutes 40 seconds (3) 3 minutes 30 seconds (4) 4 minutes 50 seconds What is the minimum number of seismic stations needed to locate most earthquake epicenters? (1) 1 (2) 2 (3) 3 (4) 4 The geologic cross section below shows limestone that was intruded. Part of the limestone (zone A) was heated intensely but was not melted. Which type of rock most likely formed in zone A? 1 gneiss 2 slate 3 marble 4 obsidian Base your answers to the following two questions on the geologic cross sections below, which represent bedrock from different areas on Earth. All the cross sections most likely represent areas of 1 crustal stability 2 mountain building 3 seashore erosion 4 plateau development Organizing information in a meaningful way, such as grouping these cross sections, is an example of 1 prediction 2 measurement 3 observation 4 classification A seismic station received the P-waves generated by an earthquake but did not receive the S-waves. Which statement best explains the absence of the S-waves? 1 The earthquake was too weak to produce S-waves. 2 The earthquake’s epicenter and focus were at the same location. 3 The S-waves were absorbed by a liquid layer as they traveled toward the seismic station. 4 The s-Waves were reflected away from the seismic station when they reached the Moho interface. Which difference between gabbro bedrock and granite bedrock causes seismic waves to travel faster in gabbro than in granite? 1 Gabbro is more dense than granite. 2 Gabbro has greater permeability than granite. 3 Gabbro has a darker color than granite. 4 Gabbro is made of smaller mineral grains than granite. The diagram below shows a cross section of a portion of Earth. The inferred motions of crustal plates are shown. Letters A through D represent locations at Earth’s surface. Which letter represents the location of the mid-Atlantic Ridge? (1) A (2) B (3) C (4) D Base your answers to the following five questions on the Earth Science Reference Tables, the map below, and your knowledge of Earth science. The map shows seismic stations X, Y and Z that have recorded seismic waves from the same earthquake. The distances from seismic stations X and Y to the earthquake epicenter have been drawn on the map. Locations A, B, C, and D represent possible earthquake epicenters. The distance from seismic station Z to the earthquake epicenter has been deliberately omitted. How far is station X from the earthquake epicenter? (1) 5,200 km (2) 2,400 km (3) 3,000 km (4) 4,000 km How long did the P-wave take to travel from the earthquake epicenter to station Y? (1) 2 min 10 sec (2) 3 min 40 sec (3) 4 min 0 sec (4) 5 min 40 sec If the earthquake’s focus was 2 kilometers below Earth’s surface, the earthquake occurred in the 1 lithosphere 2 asthenosphere 3 stiffer mantle 4 outer core Compared to the speed of S-waves in a given Earth material, the speed of P-waves is 1 always slower 2 always faster 3 always identical 4 sometimes slower and sometimes faster Station Z recorded a time difference of 6 minutes 40 seconds between the arrival of the P-waves and the arrival of the S-waves. The earthquake epicenter was located closest to location (1) A (2) B (3) C (4) D The two elements that make up the largest percentage by mass of Earth’s crust are oxygen and (1) silicon (2) potassium (3) hydrogen (4) nitrogen Which processes most likely formed the shale bedrock found near Ithaca, New York? (1) uplift and solidification (2) burial and compaction (3) heat and pressure (4) melting and recrystallization Which processes most likely formed the shale bedrock found near Ithaca, New York? (1) uplift and solidification (2) burial and compaction (3) heat and pressure (4) melting and recrystallization Base your answers to the following two questions on the map below, which shows the risk of damage from seismic activity in the United States. In the United States, most of the major damage expected from a future earthquake is predicted to occur near a (1) divergent plate boundary, only (2) convergent plate boundary, only (3) mid-ocean ridge and a divergent plate boundary (4) transform plate boundary and a hot spot Which New York State location has the greatest risk of earthquake damage? (1) Binghamton (2) Buffalo (3) Plattsburgh (4) Elmira Base your answers to the following three questions on the example of a seismogram and set of instructions for determining the Richter magnitude of an earthquake below. The example shows the Richter magnitude of an earthquake 210 kilometers from a seismic station. Instructions for determining Richter magnitude: • Determine the distance to the epicenter of the earthquake. (The distance in the example is 210 kilometers.) • Measure the maximum wave height of the S-wave recorded on the seismogram. (The height in the example is 23 millimeters.) • Place a straightedge between the distance to the epicenter (210 kilometers) and the height of the largest Swave (23 millimeters) on the appropriate scales. Draw a line connecting these two points. The magnitude of the earthquake is determined by where the line intersects the Richter magnitude scale. (The magnitude of this example is 5.0.) Using the set of instructions above and the seismogram and scales below, determine the Richter magnitude of an earthquake that was located 500 kilometers from this seismic station. Record your answer below. Identify the information shown on the seismogram that was used to determine that the distance to the epicenter was 500 kilometers. ______________________________________________________________________________________ ______________________________________________________________________________________ How long did it take the first S-wave to travel 500 kilometers to reach this seismic station? Base your answers to the following five questions on the passage below and on the map in your answer booklet. The passage describes the Gakkel Ridge found at the bottom of the Arctic Ocean. The map shows the location of the Gakkel Ridge. The Gakkel Ridge In the summer of 2001, scientists aboard the U.S. Coast Guard icebreaker Healy visited one of the least explored places on Earth. The scientists studied the 1800-kilometer-long Gakkel Ridge at the bottom of the Arctic Ocean near the North Pole. The Gakkel Ridge is a section of the Arctic Mid-Ocean Ridge and extends from the northern end of Greenland across the Arctic Ocean floor toward Russia. At a depth of about 5 kilometers below the ocean surface, the Gakkel Ridge is one of the deepest mid-ocean ridges in the world. The ridge is believed to extend down to Earth’s mantle, and the new seafloor being formed at the ridge is most likely composed of huge slabs of mantle rock. Bedrock samples taken from the seafloor at the ridge were determined to be the igneous rock peridotite. The Gakkel Ridge is also the slowest moving mid-ocean ridge. Some ridge systems, like the East Pacific Ridge, are rifting at a rate of about 20 centimeters per year. The Gakkel Ridge is rifting at an average rate of less than 1 centimeter per year. This slow rate of movement means that there is less volcanic activity along the Gakkel Ridge than along other ridge systems. However, heat from the underground magma slowly seeps up through cracks in the rocks of the ridge at structures scientists call hydrothermal (hot water) vents. During the 2001 cruise, a major hydrothermal vent was discovered at 87° N latitude 45° E longitude. On the map below, place an X on the location of the major hydrothermal vent described in the passage. Describe the relative motion of the two tectonic plates on either side of the Gakkel Ridge. _______________________________________________________________________________________ _______________________________________________________________________________________ The Gakkel Ridge is a boundary between which two tectonic plates? Identify one feature, other than hydrothermal vents, often found at mid-ocean ridges like the Gakkel Ridge that indicates heat from Earth’s interior is escaping. _______________________________________________________________________________________ State the two minerals that were most likely found in the igneous bedrock samples collected at the Gakkel Ridge. The diagram below shows a view of the ground from directly above a flagpole in New York State at solar noon on a particular day of the year. The flagpole’s shadow at solar noon is shown. Draw the position and relative length of the shadow that would be cast by this flagpole three hours later. How long would it take for the first S-wave to arrive at a seismic station 4,000 kilometers away from the epicenter of an earthquake? (1) 5 min 40 sec (2) 7 min 0 sec (3) 12 min 40 sec (4) 13 min 20 sec The photograph below shows an escarpment (cliff) located in the western United States. The directions for north and south are indicated by arrows. A fault in the sedimentary rocks is shown on the front of the escarpment. The photograph shows that the fault most likely formed (1) after the rock layers were deposited, when the north side moved downward (2) after the rock layers were deposited, when the north side moved upward (3) before the rock layers were deposited, when the south side moved downward (4) before the rock layers were deposited, when the south side moved upward Which mountain range resulted from the collision of North America and Africa, as parts of Pangea joined together in the late Pennsylvanian Period? (1) Appalachian Mountains (2) Acadian Mountains (3) Taconic Mountains (4) Grenville Mountains The two most abundant elements by mass in Earth’s crust are oxygen and (1) potassium (2) hydrogen (3) nitrogen (4) silicon On the map below, line AB is drawn across several of Earth’s tectonic plates in the South Atlantic Ocean. Which cross section best represents the plate boundaries and mantle movement beneath line AB? The diagrams below show four major types of fault motion occurring in Earth’s crust. Which type of fault motion best matches the general pattern of crustal movement at California’s San Andreas fault? Base your answers to the following two questions on the map and table below. The map shows the name and location of the volcanic peaks in the Cascade Mountain Range of the northwestern United States west of the Yellowstone Hot Spot. The table shows the major eruptions of each peak over the past 4,000 years. During which geologic epoch did the volcanic activity shown on the table occur? On the cross section provided below, place an arrow in the continental crust and an arrow in the oceanic crust to show the relative directions of plate movement. Which layer of Earth is composed of both the crust and the rigid mantle? _______________________________________________________________________________________ Base your answers to the following two questions on the map and data table shown below. The map shows some tectonic plates and the boundaries between them. Letters A and B are locations on Earth’s surface. The data table shows the depth below Earth’s surface of five earthquakes measured from location A toward location B. On the grid provided below, plot the depths of the five earthquakes from location A toward location B. Identify the type of plate boundary or geologic feature found at location B. _______________________________________________________________________________________ The diagram below represents three seismograms showing the same earthquake as it was recorded at three different seismic stations, A, B, and C. Which statement correctly describes the distance between the earthquake epicenter and these seismic stations? (1) A is closest to the epicenter, and C is farthest from the epicenter. (2) B is closest to the epicenter, and C is farthest from the epicenter. (3) C is closest to the epicenter, and A is farthest from the epicenter. (4) A is closest to the epicenter, and B is farthest from the epicenter. When a continental crustal plate collides with an oceanic crustal plate, the continental crust is forced to move over the oceanic crust. What is the primary reason that the continental crust stays on top of the oceanic crust? (1) Continental crust is less dense. (2) Continental crust deforms less easily. (3) Continental crust melts at higher temperatures. (4) Continental crust contains more mafic minerals. Base your answers to the following three questions on the diagram below, which shows details of a section of a rift valley in the center of a mid-ocean ridge. The vertical lines in the diagram represent faults and fractures within the ocean floor bedrock. What will be the primary result of the continuation of the geologic processes indicated at this location? (1) Earth’s magnetic field will reverse direction. (2) Continental crust will be forced downward. (3) Earth’s circumference will increase. (4) New oceanic crust will form. Which type of crustal plate boundary is shown in this diagram? (1) divergent (2) convergent (3) universal (4) transform The dark-colored lava flows shown in the diagram were pushed from the magma chamber onto the surface of the ocean floor. Which characteristics are present in the solid rock that formed when the lava flows cooled? (1) generally small grain size and mafic composition (2) generally small grain size and felsic composition (3) generally large grain size and mafic composition (4) generally large grain size and felsic composition Base your answers to the following four questions on the information below and on your knowledge of Earth science. In the 1930s, most scientists believed that Earth’s crust and interior were solid and motionless. A small group of scientists were talking about “continental drift,” which is the idea that Earth’s crust is not stationary, but is constantly shifting and moving. From seismic data, geophysical evidence, and laboratory experiments, scientists now generally agree that lithospheric plates move at the surface. Both Earth’s surface and interior are in motion. Solid rock in the mantle can be softened and shaped when subjected to the heat and pressure within Earth’s interior over millions of years. Subduction processes are believed by many scientists to be the driving force of plate tectonics. At present, this theory cannot be directly observed and confirmed. The lithospheric plates have moved in the past and are still moving today. The details of why and how they move will continue to challenge scientists. Earth’s crust is described as “constantly shifting and moving.” Give one example of geologic evidence that supports the conclusion that continents have drifted apart. _______________________________________________________________________________________ _______________________________________________________________________________________ The information given suggests that “subduction processes are the driving force of plate tectonics.” Identify a specific location of a subduction zone on Earth. _______________________________________________________________________________________ According to the Earth Science Reference Tables, at what inferred depth is mantle rock partially melted and slowly moving below the lithospheric plates? According to the geologic record, during which geologic time period did the lithospheric plates that made up Pangea begin to break up? The study of how seismic waves change as they travel through Earth has revealed that (1) P-waves travel more slowly than S-waves through Earth’s crust (2) seismic waves travel more slowly through the mantle because it is very dense (3) Earth’s outer core is solid because P-waves are not transmitted through this layer (4) Earth’s outer core is liquid because S-waves are not transmitted through this layer Base your answers to the following two questions on the earthquake seismogram below. When did the first P-waves arrive at this seismic station? (1) 3 minutes after an earthquake occurred 2,600 km away (2) 5 minutes after an earthquake occurred 2,600 km away (3) 9 minutes after an earthquake occurred 3,500 km away (4) 11 minutes after an earthquake occurred 3,500 km away How many additional seismic stations must report seismogram information in order to locate this earthquake? (1) one (2) two (3) three (4) four The diagram below shows some features of Earth’s crust and upper mantle. Which model most accurately shows the movements (arrows) associated with the surface features shown in the diagram? Base your answers to the following three questions on the map below. The map shows the continents of Africa and South America, the ocean between them, and the ocean ridge and transform faults. Locations A and D are on the continents. Locations B and C are on the ocean floor. The hottest crustal temperature measurements would most likely be found at location (1) A (2) B (3) C (4) D Which table best shows the relative densities of the crustal bedrock at locations A, B, C, and D? Which graph best shows the relative age of the ocean-floor bedrock from location B to location C? Base your answers to the following four questions on the diagram and map below. The diagram shows three seismograms of the same earthquake recorded at three different seismic stations, X, Y, and Z. The distances from each seismic station to the earthquake epicenter have been drawn on the map. A coordinate system has been placed on the map to describe locations. The map scale has not been included. Approximately how far away from station Y is the epicenter? (1) 1,300 km (2) 2,600 km (3) 3,900 km (4) 5,200 km The S-waves from this earthquake that travel toward Earth’s center will (1) be deflected by Earth’s magnetic field (2) be totally reflected off the crust-mantle interface (3) be absorbed by the liquid outer core (4) reach the other side of Earth faster than those that travel around Earth in the crust Seismic station Z is 1,700 kilometers from the epicenter. Approximately how long did it take the P-wave to travel to station Z? (1) 1 min 50 sec (2) 2 min 50 sec (3) 3 min 30 sec (4) 6 min 30 sec On the map, which location is closest to the epicenter of the earthquake? (1) E–5 (2) G–1 (3) H–3 (4) H–8 Base your answers to the following three questions on the diagram below. The diagram shows a model of the relationship between Earth’s surface and its interior. Mid-ocean ridges (rifts) normally form where tectonic plates are (1) converging (2) diverging (3) stationary (4) sliding past each other The motion of the convection currents in the mantle beneath the Atlantic Ocean appears to be mainly making this ocean basin (1) deeper (2) shallower (3) wider (4) narrower According to the diagram, the deep trench along the west coast of South America is caused by movement of the oceanic crust that is (1) sinking beneath the continental crust (2) uplifting over the continental crust (3) sinking at the Mid-Atlantic ridge (4) colliding with the Atlantic oceanic crust The photograph below shows an impact crater approximately 1 mile wide located in Diablo Canyon, Arizona. Describe the event that produced this crater. _______________________________________________________________________________________ Which cross section below best represents the crustal plate motion that is the primary cause of the volcanoes and deep rift valleys found at mid-ocean ridges? Most inferences about the characteristics of Earth’s mantle and core are based on (1) the behavior of seismic waves in Earth’s interior (2) well drillings from Earth’s mantle and core (3) chemical changes in exposed and weathered metamorphic rocks (4) comparisons between Moon rocks and Earth rocks The seismogram below shows P-wave and S-wave arrival times at a seismic station following an earthquake. The distance from this seismic station to the epicenter of the earthquake is approximately (1) 1,600 km (2) 3,200 km (3) 4,400 km (4) 5,600 km Base your answers to the following two questions on the reading passage and map of the western United States below and on your knowledge of Earth science. The states of Washington and Oregon have been labeled on the map. The plate boundary shown on the map is the source area for high-magnitude earthquakes in Washington and Oregon. Two hazardous zones associated with these earthquakes are also shown. Washington and Oregon Earthquakes Large-magnitude earthquakes have occurred in Washington and Oregon as a result of crustal movement along thrust faults bordering the coasts of these states. Thrust faults occur when one section of Earth’s crust slides over another section. Associated with the sudden movement of these thrust faults, coastlines can drop several feet, flooding forests with saltwater. Geologists have discovered evidence from various geologic ages of flooded coastal forests in the bedrock layers of Washington and Oregon. They have also found layers of sandstone thought to have been derived from sand deposits left by tsunamis. Using the rock record, scientists conclude that very large magnitude earthquakes occur every 300 to 500 years with the most recent large quake occurring about 200 years ago. a What is a tsunami? b State how tsunamis can affect coastal regions. a Identify the tectonic plates on both sides of the plate boundary shown on the map. b Identify the type of tectonic plate boundary shown on the map that is responsible for the thrust faults along the Washington and Oregon coastline. The cross section below shows rock layers that underwent crustal movement during an igneous intrusion in the Cretaceous Period. Which statement best describes the cause of the ridges shown? (1) The rock layers were evenly weathered. (2) Some rock layers were more resistant to weathering and erosion. (3) The igneous intrusion flowed over the surface. (4) More deposition occurred at the ridge sites after uplift. The photograph below shows deformed rock structure found on Earth’s surface. Deformed rock structure like this is most often caused by (1) crustal plate collisions (2) deposition of sediments (3) extrusion of magma (4) glacial movement The seismogram below shows the time that an earthquake P-wave arrived at a seismic station in Albany, New York. If the earthquake occurred at exactly 10:00 p.m., approximately how far from the earthquake epicenter was Albany, New York? (1) 1,900 km (2) 3,200 km (3) 4,000 km (4) 5,200 km Which seismogram was recorded approximately 4,000 kilometers from an earthquake epicenter? The diagram below shows a tectonic plate boundary. Which mantle hot spot is at a plate boundary like the one shown in this diagram? (1) Hawaii Hot Spot (2) Yellowstone Hot Spot (3) Galapagos Hot Spot (4) Canary Hot Spot Base your answers to the following six questions on the reading passage and maps below and on your knowledge of Earth science. The enlarged map shows the location of volcanoes in Colombia, South America. Fire and Ice — and Sluggish Magma On the night of November 13, 1985, Nevado del Ruiz, a 16,200-foot (4,938 meter) snowcapped volcano in northwestern Colombia, erupted. Snow melted, sending a wall of mud and water raging through towns as far as 50 kilometers away, and killing 25,000 people. Long before disaster struck, Nevado del Ruiz was marked as a trouble spot. Like Mexico City, where an earthquake killed at least 7,000 people in October 1985, Nevado del Ruiz is located along the Ring of Fire. This ring of islands and the coastal lands along the edge of the Pacific Ocean are prone to volcanic eruptions and crustal movements. The ring gets its turbulent characteristics from the motion of the tectonic plates under it. The perimeter of the Pacific, unlike that of the Atlantic, is located above active tectonic plates. Nevado del Ruiz happens to be located near the junction of four plate boundaries. In this area an enormous amount of heat is created, which melts the rock 100 to 200 kilometers below Earth’s surface and creates magma. Nevado del Ruiz hadn’t had a major eruption for 400 years before this tragedy. The reason: sluggish magma. Unlike the runny, mafic magma that makes up the lava flows of oceanic volcanoes such as those in Hawaii, the magma at this type of subduction plate boundary tends to be sticky and slow moving, forming the rock andesite when it cools. This andesitic magma tends to plug up the opening of the volcano. It sits in a magma chamber underground with pressure continually building up. Suddenly, tiny cracks develop in Earth’s crust, causing the pressure to drop. This causes the steam and other gases dissolved in the magma to violently expand, blowing the magma plug free. Huge amounts of ash and debris are sent flying, creating what is called an explosive eruption. Oddly enough, the actual eruption of Nevado del Ruiz didn’t cause most of the destruction. It was caused not by lava but by the towering walls of sliding mud created when large chunks of hot ash and pumice mixed with melted snow. What are the names of the four tectonic plates located near the Nevado del Ruiz volcano? What caused most of the destruction associated with the eruption of Nevado del Ruiz? _______________________________________________________________________________________ _______________________________________________________________________________________ What caused the magma to expand, blowing the magma plug free? _______________________________________________________________________________________ _______________________________________________________________________________________ Vesicular texture is very common in igneous rocks formed during andesitic eruptions. Explain how this texture is formed. _______________________________________________________________________________________ _______________________________________________________________________________________ Why are eruptions of Nevado del Ruiz generally more explosive than most Hawaiian volcanic eruptions? _______________________________________________________________________________________ _______________________________________________________________________________________ Describe one emergency preparation that may reduce the loss of life from a future eruption of the Nevado del Ruiz volcano. _______________________________________________________________________________________ Approximately how long does an earthquake P-wave take to travel the first 6500 kilometers after the earthquake occurs? (1) 6.5 min (2) 8.0 min (3) 10.0 min (4) 18.5 min What are the two most abundant elements by mass found in Earth’s crust? (1) aluminum and iron (2) sodium and chlorine (3) calcium and carbon (4) oxygen and silicon Base your answers to the following three questions on the map below. The map shows the locations of deepsea core drilling sites numbered 1 through 4. The approximate location of the East Pacific Ridge is shown by a dashed line. Point A is located on the East Pacific Ridge. At point A, the East Pacific Ridge is the boundary between the (1) Cocos Plate and the North American Plate (2) South American Plate and the Nazca Plate (3) Pacific Plate and the South American Plate (4) Pacific Plate and the Nazca Plate At which drilling site would the oldest igneous bedrock most likely be found? (1) 1 (2) 2 (3) 3 (4) 4 Compared to the thickness and density of the continental crust of South America, the oceanic crust of the Pacific floor is (1) thinner and less dense (2) thinner and more dense (3) thicker and less dense (4) thicker and more dense Base your answers to the following two questions on the map below. Seismic stations are located at the four cities shown on the map. Letter X represents the epicenter of an earthquake determined from seismic waves recorded at all four cities. At which city is there a difference of approximately 3 minutes and 20 seconds between the arrival times of the P-waves and the S-waves? (1) New Orleans (2) Louisville (3) Pittsburgh (4) New York City Which map correctly shows how the location of the epicenter was determined? The block diagram below shows the bedrock age as measured by radioactive dating and the present location of part of the Hawaiian Island chain. These volcanic islands may have formed as the Pacific Plate moved over a mantle hot spot. This diagram provides evidence that the Pacific Crustal Plate was moving toward the (1) south (2) east (3) southwest (4) northwest Base your answers to the following two questions on the diagram below, which shows a portion of Earth’s interior. Point A is a location on the interface between layers. The arrows shown in the asthenosphere represent the inferred slow circulation of the plastic mantle by a process called (1) insolation (2) convection (3) conduction (4) radiation The temperature of rock at location A is approximately (1) 600°C (2) 1,000°C (3) 2,600°C (4) 3,000°C The diagram below shows the bedrock structure beneath a series of hills. Which process was primarily responsible for forming the hills? (1) folding (2) faulting (3) deposition (4) vulcanism The map below shows the Atlantic Ocean divided into zones A, B, C, and D. The Mid-Atlantic Ridge is located between zones B and C. Which graph best represents the geologic age of the surface bedrock on the ocean bottom? Tectonic plate boundaries may be classified as divergent, convergent, or transform. For each location listed in the data table below, place an X in the proper column to indicate the type of plate boundary at that location. A seismic station in Massena, New York, recorded the arrival of the first P-wave at 1:30:00 (1 hour, 30 minutes, 00 seconds) and the first S-wave from the same earthquake at 1:34:30. a Determine the distance, in kilometers, from Massena to the epicenter of this earthquake. b State what additional information is needed to determine the location of the epicenter of this earthquake. Base your answers to the following four questions on the maps below, which show the spread of a volcanic ash cloud from the 1982 eruption of El Chichón in Mexico, as seen from weather satellites. Identify the direction toward which the ash cloud spread from April 5 to April 25. ______________________________________ State what caused the main ash cloud to spread in the pattern shown on the map of April 25, 1982. _______________________________________________________________________________________ State the most likely effect of the ash cloud on the temperature of areas under the cloud on April 25, 1982. _______________________________________________________________________________________ As the ash cloud moved away from El Chichón, some ash particles fell back to Earth. a Describe how the size of the particles affected the pattern of deposition. b Describe how the density of the particles affected the pattern of deposition. According to the graph, what is the approximate number of days each year that thunderstorms occur at locations along the 40° N parallel of latitude? (1) 8 days (2) 18 days (3) 24 days (4) 32 days Andrija Mohorovičic´ discovered the interface between the crust and the mantle that is now named for him. His discovery of the “Moho” was based on analysis of (1) landscape boundaries (2) continental coastlines (3) erosional surfaces (4) seismic waves The observed difference in density between continental crust and oceanic crust is most likely due to differences in their (1) composition (2) thickness (3) porosity (4) rate of cooling Which diagram correctly shows how mantle convection currents are most likely moving beneath colliding lithospheric plates? Base your answers to the following two questions on the diagram below, which shows models of two types of earthquake waves. Model A best represents the motion of earthquake waves called (1) P-waves (compressional waves) that travel faster than S-waves (shear waves) shown in model B (2) P-waves (compressional waves) that travel slower than S-waves (shear waves) shown in model B (3) S-waves (shear waves) that travel faster than P-waves (compressional waves) shown in model B (4) S-waves (shear waves) that travel slower than P-waves (compressional waves) shown in model B The difference in seismic station arrival times of the two waves represented by the models helps scientists determine the (1) amount of damage caused by an earthquake (2) intensity of an earthquake (3) distance to the epicenter of an earthquake (4) time of occurrence of the next earthquake Base your answers to the following two questions on the map below, which shows the depths of selected earthquakes along the crustal plate boundary near the west coast of South America. Letters A, B, C, and D are epicenter locations along a west-to-east line at the surface. The relative depth of each earthquake is indicated. Which graph best shows the depth of earthquakes beneath epicenters A, B, C, and D? The earthquake beneath epicenter D occurred in which part of Earth’s interior? (1) crust (2) rigid mantle (3) asthenosphere (4) stiffer mantle Base your answers to the following two questions on the diagram below, which shows an incomplete concept map identifying the types of plate boundaries. Information in the boxes labeled A, B, C, D, and E has been deliberately omitted. On the chart provided below, write the information that should be placed in the boxes labeled A, B, and C that will correctly complete those portions of the concept map. On the geographic map provided below, write the letters D and E on the plate boundary locations where the indicated movements are occurring. Write the letters approximately the same size as shown on the concept map and locate the letters directly on the plate boundary. Base your answers to the following three questions on the map below, which shows the location of the PeruChile Trench. The Peru-Chile Trench marks the boundary between the (1) Pacific Plate and the Antarctic Plate (2) Nazca Plate and the South American Plate (3) North American Plate and the Cocos Plate (4) Caribbean Plate and the Scotia Plate In which diagram do the arrows best represent the motions of Earth’s crust at the Peru-Chile Trench? Which observation provides the best evidence of the pattern of crustal movement at the Peru-Chile Trench? (1) the direction of flow of warm ocean currents (2) the mineral composition of samples of mafic mantle rock (3) comparison of the rates of sediment deposition (4) the locations of shallow-focus and deep-focus earthquakes Base your answers to the following three questions on the map and data table below. The map shows the locations of volcanic islands and seamounts that erupted on the seafloor of the Pacific Plate as it moved northwest over a stationary mantle hotspot beneath the lithosphere. The hotspot is currently under Kilauea. Island size is not drawn to scale. Locations X, Y, and Z are on Earth’s surface. Approximately how far has location X moved from its original location over the hotspot? (1) 3,600 km (2) 2,500 km (3) 1,800 km (4) 20 km According to the data table, what is the approximate speed at which the island of Kauai has been moving away from the mantle hotspot, in kilometers per million years? (1) 1 (2) 10 (3) 100 (4) 1,000 Which lithospheric plate boundary features are located at Y and Z? (1) trenches created by the subduction of the Pacific Plate (2) rift valleys created by seafloor spreading of the Pacific Plate (3) secondary plates created by volcanic activity within the Pacific Plate (4) mid-ocean ridges created by faulting below the Pacific Plate The diagram below shows land features that have been disrupted by an earthquake. Which type of crustal movement most likely caused the displacement of features in this area? (1) vertical lifting of surface rock (2) folding of surface rock (3) down-warping of the crust (4) movement along a transform fault Base your answers to the following two questions on the photograph below, which shows an outcrop of sedimentary rock layers that have been tilted and slightly metamorphosed. The tilted rock structure shown in the photograph is most likely the result of the (1) deposition of rock fragments on a mountain slope (2) reversal of past magnetic poles (3) passage of seismic waves (4) collision of crustal plates Tilted, slightly metamorphosed rock layers such as these are typically found in which New York State landscape region? (1) Taconic Mountains (2) Atlantic Coastal Plain (3) Tug Hill Plateau (4) Erie-Ontario Lowlands The diagram below is a seismogram of the famous San Francisco earthquake of 1906, recorded at a seismic station located 6,400 kilometers from San Francisco. Which time scale best represents the arrival-time difference between P-waves and S-waves at this station? Base your answers to the following two questions in part on the news article and map below. Points A and B on the map are reference points. Huge Quake Possible in Oregon Valley Scientists have warned for years that a magnitude 8 or 9 earthquake could strike about 30 miles off the Oregon coast, causing huge tsunamis (large ocean waves) and tremendous damage. Now scientists say these earthquakes could be centered much farther inland and cause severe damage to a larger area, including cities in Oregon such as Portland, Salem, and Eugene. Geologic evidence suggests that strong quakes in this area occur about every 400 years, plus or minus 200 years. The last one, believed to be a magnitude 9, occurred 300 years ago. A magnitude 8 quake can cause tremendous damage. The San Francisco quake of 1906 has been estimated at 7.9. The Mexico City quake of 1985 that left thousands dead was measured at 8.1. The cross section below shows the lithosphere and asthenosphere between points A and B on the map. a On the cross section provided below, draw an arrow in the Juan de Fuca Plate to indicate the direction of the relative movement of the plate. b Identify the type of tectonic plate boundary that exists at the Juan de Fuca Ridge. c Identify the name of the plate in the cross section labeled x. d How does the average earthquake depth beneath the Oregon coastline compare to the average earthquake depth beneath Mt. Hood? An emergency management specialist in Portland, Oregon, is developing a plan that would help save lives or prevent property damage in the event of a future earthquake. Describe two actions or ideas that should be included in the plan. A huge undersea earthquake off the Alaskan coastline could produce a (1) tsunami (2) cyclone (3) hurricane (4) thunderstorm Base your answers to the following three questions on the data table below, which gives information collected at seismic stations A, B, C, and D for the same earthquake. Some of the data has been deliberately omitted. What is the most probable reason for the absence of S-waves at station A? (1) S-waves cannot travel through liquids. (2) S-waves were not generated at the epicenter. (3) Station A was located on solid bedrock. (4) Station A was located too close to the epicenter. What is the approximate distance from station C to the earthquake epicenter? (1) 3,200 km (2) 2,400 km (3) 1,600 km (4) 1,000 km How long did it take the P-wave to travel from the epicenter of the earthquake to seismic station D? (1) 00:46:20 (2) 00:39:20 (3) 00:17:20 (4) 00:09:40 Base your answers to the following three questions on the map below, which shows the location of midocean ridges and the age of some oceanic bedrock near these ridges. Letters A through D are locations on the surface of the ocean floor. What is the most probable age, in millions of years, of the bedrock at location B? (1) 5 (2) 12 (3) 48 (4) 62 Rising convection currents in the asthenosphere would most likely be under location (1) A (2) B (3) C (4) D The age of oceanic bedrock on either side of a mid-ocean ridge is supporting evidence that at the ridges, tectonic plates are (1) diverging (2) converging (3) locked in place (4) being subducted Base your answers to the following four questions on the passage and map below and on your knowledge of Earth science. The passage provides some information about the sediments under Portland, Oregon, and the map shows where Portland is located. Bad seismic combination under Portland: Earthquake faults and jiggly sediment Using a technique called seismic profiling, researchers have found evidence of ancient earthquake faults under Portland, Oregon. The faults may still be active, a USGS [United States Geological Survey] seismologist will announce tomorrow. The research also turned up a 250-foot deep layer of silt and mud, deep under the city, which may have been caused by a catastrophic ice dam break some 15,000 years ago. The two findings could together mean bad news, as soft sediment is known to amplify ground shaking during strong earthquakes. In the 1989 San Francisco earthquake, much of the damage to buildings was caused by liquefaction, a shaking and sinking of sandy, water-saturated soil along waterways. . . . — Robert Roy Britt excerpted from “Bad seismic combination under Portland: Earthquake faults and jiggly sediment” explorezone.com 05/03/99 Explain why Portland is likely to experience a major earthquake. _______________________________________________________________________________________ _______________________________________________________________________________________ Why is the presence of a layer of silt and mud deep under the city a danger to Portland? _______________________________________________________________________________________ _______________________________________________________________________________________ Describe one precaution that can be taken to prevent or reduce property damage in preparation for a future earthquake in Portland. _______________________________________________________________________________________ _______________________________________________________________________________________ What type of tectonic plate boundary is shown at the San Andreas Fault? __________________________________________________ Earth’s Crust Test Prep Teacher Answer Key – Guide According to the plate tectonics theory, the Peru-Chile Trench and the Andes Mountains formed along the west coast of South America because the South American Plate 1 collided with the Nazca Plate If the crust symbol represents basalt with normal magnetic polarity, what does the crust symbol most likely represent? 2 igneous rock with reversed magnetic polarity The geological features of the ocean floor in this region resulted from 4 rising convection currents in the mantle The P-wave of an earthquake originating 2,600 kilometers from seismic station A arrived at 5:24:45 a.m. What was the arrival time of the S-wave from the same earthquake? (3) 5:28:45 a.m. The epicenter is closest to point (1) D Which landscape region probably resulted from the erosion of faulted rock layers? Which location is closest to a divergent plate boundary at an oceanic ridge? (1) A Which surface location had the least damage? (3) E This earthquake provides evidence for the existence of 3 faulting of bedrock at Northridge Which information would have been most useful for locating the earthquake epicenter? 1 the difference between the arrival times of the P-wave and the S-wave The greatest surface damage occurred in zone IX because 2 of local conditions at zone IX Which crustal plate boundary is most closely associated with this earthquake? 4 North American Plate — Pacific Plate Which statement most accurately compares Earth’s crust and Earth’s mantle? 1 The crust is thinner and less dense than the mantle. Based on the theory of plate tectonics, it is inferred that over the past 250 million years North America has moved toward the (1) northwest According to tectonic plate maps, New York State is presently located (4) near the center of a large plate Which statement best explains why only one type of seismic wave was recorded at location B? (1) S-waves cannot travel through the liquid outer core. A seismic station located at point A is 5400 kilometers away from the epicenter of the earthquake. If the arrival time for the P-wave at point A was 2:00 p.m., the arrival time for the S-wave at point A was approximately (2) 2:07 p.m. The cross section below shows a drill rig used to collect rock samples from below Earth’s surface. The rock samples collected from the bottom of the drill hole came from which Earth layer? (1) lithosphere On the map above, place an X on the map to show the location of the Nazca Plate. The center of the student-drawn X is located somewhere on the Nazca Plate shaded below. Explain why most major earthquakes are found in specific zones instead of being randomly scattered across Earth’s surface. Acceptable responses include, but are not limited to: — Most major earthquakes occur at tectonic plate boundaries. — Most earthquakes occur at the location of major fault zones. — Crustal movement at plate boundaries causes frequent earthquake activity. Identify the source of the magma for the volcanic activity in Hawaii. Acceptable responses include, but are not limited to: — a hot spot — a magma plume — the mantle Identify the type of plate movement responsible for the presence of the volcano at location A. Acceptable responses include, but are not limited to: — divergent — diverging lithospheric plates — seafloor spreading — rifting In which Earth layer are most convection currents that cause seafloor spreading thought to be located? (2) asthenosphere An earthquake’s magnitude can be determined by (1) analyzing the seismic waves recorded by a seismograph A seismic station is recording the seismic waves produced by an earthquake that occurred 4200 kilometers away. Approximately how long after the arrival of the first P-wave will the first S-wave arrive? (2) 5 min 50 sec Which graph best shows the inferred density of Earth’s interior as depth increases from the upper mantle to the lower mantle? The block diagram below shows a tectonic plate boundary. Points A and B represent locations on Earth’s surface. Which graph best shows the depths of most major earthquakes whose epicenters lie between A and B? At the time of the eruption, the wind direction was primarily from the (3) north How many centimeters thick was the ash beneath point X? (2) 15 In addition to the ash, solid rock formed on Mt. Hekla from the lava extruded during this eruption. This rock is most likely (3) fine-grained igneous State the approximate temperature at point X. Any value from 500°C to 1200°C On what tectonic plate are both North Island and White Island located? Indian-Australian Plate Describe the type of tectonic plate motion that formed the Hikurangi Trench. Acceptable responses include, but are not limited to: — subduction — convergence — plate collision Describe one action that people on North Island should take if a tsunami warning is issued. Acceptable responses include, but are not limited to: — move to higher ground — evacuate — move inland A seismic station recorded the arrival of a P-wave at 10:00:00 a.m. The S-wave arrival was recorded at 10:04:20 a.m. What is the approximate distance between the earthquake epicenter and the seismic station? (3) 2.9 x 103 km Through which materials can P-waves travel? 4 solid rock, magma, water, and natural gas Which observed feature would provide the best evidence of crustal stability? 1 horizontal sedimentary layers Which cross-sectional diagram of a portion of the crust and mantle best shows the pattern of mantle convection currents that are believed to cause the formation of a mid-ocean ridge? The diagram below shows a cross section of a portion of Earth’s crust. Altitude is shown in meters above sea level. This landscape region is best classified as an eroded 2 plateau The thinnest section of Earth’s crust is found beneath 1 oceans In which layer of Earth’s interior is the inferred temperature 6,000°C? 3 outer core Scientists have classified Earth’s interior into the zones shown based primarily on evidence gained by studying 4 earthquake seismic waves The composition of Earth’s core is thought to be the same as the composition of many 1 meteorites Which graph best represents the relationship between depth below Earth’s surface and density? The diagram below shows the interaction of two tectonic plates. The type of plate boundary represented in the diagram most likely exists between the (3) South American Plate and the Nazca Plate State the latitude and longitude of this earthquake epicenter. Express your answers to the nearest tenth of a degree and include the compass directions. 44.5° N (latitude) and 73.7° W (longitude) - The correct compass directions and degrees must be included for both latitude and longitude. What is the minimum number of seismographic stations needed to locate the epicenter of an earthquake? 3 or three Explain why this earthquake was most likely felt with greater intensity by people in Peru, New York, than by people in Lake Placid, New York. Acceptable responses include, but are not limited to: Peru is closer to the epicenter. A seismic station located 1,800 kilometers from the epicenter recorded the P-wave and S-wave arrival times or this earthquake. What was the difference in the arrival time of the first P-wave and the first S-wave? 3 min 0 sec (±20 sec) Explain why most earthquakes that occur in the crust beneath location B are shallower than most earthquakes that occur in the crust beneath location C. Acceptable responses include, but are not limited to: Location B is at a transform fault, and location C is at a subduction boundary. Location B has horizontal plate movement, but location C has vertical plate movement. There is a transform plate boundary at B. There is a subducting plate at C. Explain why location A has a greater probability of experiencing a major earthquake than location D. Acceptable responses include, but are not limited to: A is located at a plate boundary, and D is not located at a plate boundary. Crustal plates are colliding at A, and no plate collision is occurring at D. Location A is on the Pacific Ring of Fire. Explain why a volcanic eruption is more likely to occur at location E than at location F. Acceptable responses include, but are not limited to: E is located above a mantle hot spot. E is the Canary Islands Hot Spot. F is near the center of a tectonic plate. Explain why the geologic age of the oceanic bedrock increases from location G to location H. Acceptable responses include, but are not limited to: Location G is at the ridge and is presently forming, while H was at the ridge in the past. Location H is moving away from the new crust forming in the region at G. The youngest ocean-floor bedrock is at the mid-ocean ridge. The plates are diverging at the Southeast Indian Ridge. Which coastal area is most likely to experience a severe earthquake? (4) west coast of South America A seismic station 4000 kilometers from the epicenter of an earthquake records the arrival time of the first Pwave at 10:00:00. At what time did the first S-wave arrive at this station? (2) 10:05:40 Which statement correctly describes the density of Earth’s mantle compared to the density of Earth’s core and crust? (1) The mantle is less dense than the core but more dense than the crust. Convection currents in the plastic mantle are believed to cause divergence of lithospheric plates at the (4) Iceland Hot Spot Arrows in the block diagram below show the relative movement along a tectonic plate boundary. Between which two tectonic plates does this type of plate boundary exist? (4) Pacific Plate and North American Plate Identify one of the minerals found in the andesite rock of the Three Sisters volcanoes. Acceptable responses include, but are not limited to: — quartz — plagioclase feldspar — biotite — amphibole (hornblende) — pyroxene Note: Do not accept feldspar only. The cross section below represents Earth’s interior beneath the Three Sisters. Place a triangle, ▲, on the cross section to indicate the location where the new volcano will most likely form. A ▲ should be placed on Earth’s surface above the magma chamber. Also allow credit if a symbol other than a ▲ is used. On the same cross section above, place arrows through each point, X, Y, and Z, to indicate the relative motion of each of these sections of the lithosphere. Three arrows should show the correct directions, even if the arrows do not pass through the dots. Example of a correct response for the previous 2 questions: The photograph below represents a mountainous area in the Pacific Northwest. Scientists believe that sedimentary rocks like those represent evidence of crustal change because these rocks were 3 originally deposited in horizontal layers How far from an earthquake epicenter is a city where the difference between the P-wave and S-wave arrival times is 6 minutes and 20 seconds? (4) 4.7 x 103 km The photograph below shows a large crater located in the southwestern United States. Some fragments taken from the site have a nickel-iron composition. This evidence indicates that the crater probably was formed by 1 the impact of a meteorite from space Which map best represents the general pattern of magnetism in the oceanic bedrock near the mid-Atlantic Ridge? Which features are commonly formed at the plate boundaries where continental crust converges with oceanic crust? 2 a deep ocean trench and a continental volcanic mountain range near the coast The pattern of distribution of the ash from the volcano was most likely caused by the direction of the 4 atmospheric air movements The age of this volcanic eruption was most accurately determined to be Holocene by measuring the radioactive 2 carbon in trees buried by the ash This volcanic eruption is most useful to scientists today as a relative time marker in the geologic record of this map region because the 3 volcanic ash spread quickly over a large area Which city has the greatest danger of damage from an earthquake? 2 Parkfield This fault zone is located along the boundary between which two crustal plates? 2 North American plate and Pacific plate If a large earthquake were to occur at San Diego, the earliest indication at another California location of the occurrence of that earthquake would be the arrival of the (3) P-waves at Oceanside Which diagram best represents the relative movements of the crustal plates along the San Andreas Fault in the map area? Which map best represents the location of the primary San Andreas Fault line? The drawing below shows the effects of an earthquake on a small part of Earth’s surface. Letters A and B indicate land on opposite sides of a cliff that formed along a fault during the earthquake. In relation to the position of side B, the movement of side A was 4 westward and upward A student set up the activity shown in the diagram below to demonstrate how convection cells in Earth’s mantle could cause crustal plates to converge. Which diagram shows the bet placement of heat sources to cause the blocks to converge? A seismograph records the arrival of a P-wave at 11:13 a.m. If the earthquake occurred 4,000 kilometers from the recording station, when did the earthquake occur? (1) 11:06 a.m. At which depth below Earth’s surface is the density most likely 9.5 grams per cubic centimeter? (3) 3,500 km Which letter is located on the boundary between two landscape regions? (2) B What happens to P-waves and S-waves from a crustal earthquake when the waves reach Earth’s outer core? (2) P-waves are transmitted through the outer core, but S-waves are not transmitted. Where are earthquakes on and around Hawaii located? 4 scattered across the area Rock collected from the side of Kilauea Volcano has the following mineral composition: 5% plagioclase feldspar, 68% pyroxene, 25% olivine, and 2% hornblende. What type of rock is this? 2 scoria Which inference concerning the distribution of earthquakes and recent volcanic eruptions on this island is most accurate? 3 Many earthquakes occur near recent volcanic eruptions. A scientist wants to film underwater volcanic activity that is forming a new island in the Hawaiian Island chain. In which direction from Hawaii should she concentrate her efforts? 3 southeast Hawaii is located near the middle of which tectonic plate? 4 Pacific plate What is the primary method of heat transfer through solid rock during contact metamorphism? 4 conduction What is the approximate location of the earthquake’s epicenter? (1) 36° N, 90° W What was the approximate travel time for the earthquake’s P-wave from the epicenter to Syracuse, New York? (3) 3 min Which city would have issued the report: “Heavy furniture moved, everyone felt the earthquake, and many people were frightened and ran outdoors”? 1 Cincinnati Which statement best describes the earthquake waves recorded at Louisville? (2) P-waves arrived ahead of S-waves. For which city was the difference in arrival times between P-waves and S-waves greatest? 4 Boston Folding and erosion occurred after the formation of the (3) Erie coal, but before formation of Freeport sandstone Beneath which surface location is Earth’s crust the thinnest? (1) East Pacific Ridge Which cross section best shows the inferred thickness of Earth’s interior layers that cause these different velocities? Which diagram best shows the magnetic pattern and relative age of the igneous bedrock on the west side of the ridge? The Tonga Trench is located at the tectonic boundary between the Pacific Plate and the (3) Indian-Australian Plate The greatest number of earthquakes shown in the cross section occurred (4) at a depth between 300 and 600 km Which cross section has arrows that best represent the relative motion of the crustal plates along the WadatiBenioff zone beneath the Tonga Trench? The latitude and longitude of the center of Vanau Leva is closest to (3) 17° S 179° E Explain how the seismic tracings recorded at station A and station B indicate that station A is farther from the earthquake epicenter than station B. Acceptable responses include, but are not limited to: — The arrival time of the P-wave at station A is later than the arrival time of the P-wave at station B. — The arrival time difference between the P-wave and S-wave is greater at station A. — The amplitudes of the P-wave and S-wave tracings are greater on the seismogram at station B. Seismic station A is located 5,400 kilometers from the epicenter of the earthquake. How much time would it take for the first S-wave produced by this earthquake to reach seismic station A? 15 minutes 50 seconds (±10 seconds) If an asteroid struck Earth 65 million years ago, what surface feature was most likely created by this asteroid impact? Acceptable responses include, but are not limited to: — crater — impact crater — large hole Identify one geologic process occurring on Earth that could have hidden or even destroyed this inferred impact feature. Acceptable responses include, but are not limited to: — deposition of sediment — erosion — subduction — volcanic lava flow — weathering Explain how an asteroid impact may have been able to cause a worldwide mass extinction of dinosaurs. Acceptable responses include, but are not limited to: — Dust that was thrown into Earth’s atmosphere caused a change in Earth’s climate. — The impact caused fires that killed plants and animals. — Dust from the impact blocked sunlight that cooled Earth and caused many green plants to die. Great volcanic eruptions send dust and ash into the stratosphere. Weeks after such great eruptions, air temperatures are often (1) cooler than normal because the atmosphere is less transparent A P-wave takes 8 minutes and 20 seconds to travel from the epicenter of an earthquake to a seismic station. Approximately how long will an S-wave take to travel from the epicenter of the same earthquake to this seismic station? (3) 15 min 00 sec What are the most likely geologic ages of volcanoes B and D? (1) B is 5 million years old and D is 12 million years old. Identify the texture and relative density of the granitic bedrock of the continental crust and the basaltic bedrock of the oceanic crust. Acceptable responses include, but are not limited to: Granitic bedrock Texture: Density: — coarse — low density — nonvesicular — 2.7 g/cm3 Basaltic bedrock Texture: — fine — vesicular or nonvesicular Density : — high density — 3.0 g/cm3 The minerals biotite and amphibole may be found in igneous bedrock of both the oceanic crust and the continental crust. Identify two other minerals commonly found in the basaltic oceanic crust. Acceptable responses include, but are not limited to: — olivine — pyroxene or augite — plagioclase or plagioclase feldspar Note: Do not accept “feldspar” only. Identify the part of Earth’s lithosphere represented by layer X. Acceptable responses include, but are not limited to: — rigid mantle — uppermost part of the mantle Identify the crustal feature located at point A. Acceptable responses include, but are not limited to: — trench — Peru-Chile trench — a subduction zone — a convergent boundary — a fault Identify the tectonic plate motion that is causing an increase in the distance between South America and Africa. Acceptable responses include, but are not limited to: — divergence — seafloor spreading Bedrock samples were taken at the mid-ocean ridge and points B and C. On the grid below, draw a line to show the relative age of the bedrock samples between these locations. Example response: The line may be curved or straight and the lowest point should be at the mid-ocean ridge. The seismogram recorded at station A would show the (2) earliest arrival time of P-waves An earthquake’s first P-wave arrives at a seismic station at 12:00:00. This P-wave has traveled 6000 kilometers from the epicenter. At what time will the first S-wave from the same earthquake arrive at the seismic station? (2) 12:07:40 The movement of tectonic plates is inferred by many scientists to be driven by (3) convection currents in the asthenosphere Which two tectonic plates are separated by a mid-ocean ridge? (4) North American and Eurasian Identify the type of tectonic plate motion represented by the arrow shown at D. Acceptable responses include, but are not limited to: — subduction — convergence Identify the type of tectonic motion represented by the arrows shown at A, B, and C. Acceptable responses include, but are not limited to: — transform movement — faulting — The plates slide past each other. Which elements are represented by the letters a and b, respectively? 4 oxygen and silicon Compared to the continental crust, the oceanic crust is 2 more dense Which statement best explains this pattern of wave recordings? (4) Layers with different properties inside Earth absorb or bend seismic waves. Collisions between oceanic plates and continental plates are thought to result primarily from 2 convection currents in the mantle Which information indicates that new seafloor rock is forming along a mid-ocean ridge and then moving horizontally away from the ridge? 4 The age of seafloor rock increases as the distance from the mid-ocean ridge increases. An earthquake shear wave generally travels faster as the wave moves deeper into Earth’s interior because greater depths have 3 greater rock density Which location on the map below is closest to the epicenter of this earthquake? (3) Y Which seismogram was recorded at Tampa? 3 seismogram C What was the origin time of this earthquake? (1) 2:33:00 a.m. The P-wave generated by this earthquake took 2 minutes and 40 seconds to reach one of the seismic stations. Approximately how long did the S-wave take to reach the same seismic station? (4) 4 minutes 50 seconds What is the minimum number of seismic stations needed to locate most earthquake epicenters? (3) 3 Which type of rock most likely formed in zone A? 3 marble All the cross sections most likely represent areas of 2 mountain building Organizing information in a meaningful way, such as grouping these cross sections, is an example of 4 classification A seismic station received the P-waves generated by an earthquake but did not receive the S-waves. Which statement best explains the absence of the S-waves? 3 The S-waves were absorbed by a liquid layer as they traveled toward the seismic station. Which difference between gabbro bedrock and granite bedrock causes seismic waves to travel faster in gabbro than in granite? 1 Gabbro is more dense than granite. . Which letter represents the location of the mid-Atlantic Ridge? (3) C How far is station X from the earthquake epicenter? (4) 4,000 km How long did the P-wave take to travel from the earthquake epicenter to station Y? (4) 5 min 40 sec If the earthquake’s focus was 2 kilometers below Earth’s surface, the earthquake occurred in the 1 lithosphere Compared to the speed of S-waves in a given Earth material, the speed of P-waves is 2 always faster Station Z recorded a time difference of 6 minutes 40 seconds between the arrival of the P-waves and the arrival of the S-waves. The earthquake epicenter was located closest to location (2) B The two elements that make up the largest percentage by mass of Earth’s crust are oxygen and (1) silicon Which processes most likely formed the shale bedrock found near Ithaca, New York? (4) melting and recrystallization Which processes most likely formed the shale bedrock found near Ithaca, New York? (2) burial and compaction In the United States, most of the major damage expected from a future earthquake is predicted to occur near a (4) transform plate boundary and a hot spot Which New York State location has the greatest risk of earthquake damage? (3) Plattsburgh Using the set of instructions above and the seismogram and scales below, determine the Richter magnitude of an earthquake that was located 500 kilometers from this seismic station. Record your answer below. Allow credit for a response from 6.0 to 6.2 Identify the information shown on the seismogram that was used to determine that the distance to the epicenter was 500 kilometers. Acceptable responses include, but are not limited to: — the lag time between the P-wave arrival and the S-wave arrival — the difference in arrival time for the P-wave and S-wave — the P-wave and S-wave arrival times — 61 seconds How long did it take the first S-wave to travel 500 kilometers to reach this seismic station? Allow credit for any answer from 2 minutes 0 seconds to 2 minutes 20 seconds. On the map below, place an X on the location of the major hydrothermal vent described in the passage. Allow credit if the center of the X falls within the circle shown. Describe the relative motion of the two tectonic plates on either side of the Gakkel Ridge. Acceptable responses include, but are not limited to: — The plates are moving apart or spreading. — The tectonic plates are moving away from each other. — The ridge is a diverging plate boundary. — rifting The Gakkel Ridge is a boundary between which two tectonic plates? Allow credit for both North American Plate and Eurasian Plate. Identify one feature, other than hydrothermal vents, often found at mid-ocean ridges like the Gakkel Ridge that indicates heat from Earth’s interior is escaping. Acceptable responses include, but are not limited to: — magma/lava — volcanoes — smoker vents State the two minerals that were most likely found in the igneous bedrock samples collected at the Gakkel Ridge. Allow credit for both pyroxene (augite) and olivine. The diagram below shows a view of the ground from directly above a flagpole in New York State at solar noon on a particular day of the year. The flagpole’s shadow at solar noon is shown. Draw the position and relative length of the shadow that would be cast by this flagpole three hours later. • Allow 1 credit if the shadow three hours later is drawn within the dashed lines shown below. • Allow 1 credit if the length of the shadow after three hours is longer than the solar noon shadow. Allow this credit even if the direction of the shadow is incorrectly drawn. How long would it take for the first S-wave to arrive at a seismic station 4,000 kilometers away from the epicenter of an earthquake? (3) 12 min 40 sec The photograph shows that the fault most likely formed (1) after the rock layers were deposited, when the north side moved downward Which mountain range resulted from the collision of North America and Africa, as parts of Pangea joined together in the late Pennsylvanian Period? (1) Appalachian Mountains The two most abundant elements by mass in Earth’s crust are oxygen and (4) silicon Which cross section best represents the plate boundaries and mantle movement beneath line AB? The diagrams below show four major types of fault motion occurring in Earth’s crust. Which type of fault motion best matches the general pattern of crustal movement at California’s San Andreas fault? During which geologic epoch did the volcanic activity shown on the table occur? Allow credit for Holocene Epoch. On the cross section provided below, place an arrow in the continental crust and an arrow in the oceanic crust to show the relative directions of plate movement. Allow credit for a correct response. Acceptable responses include, but are not limited to, this example: Which layer of Earth is composed of both the crust and the rigid mantle? Allow credit for lithosphere. On the grid provided below, plot the depths of the five earthquakes from location A toward location B. Allow credit if four or five points are correctly plotted (±10 km). Acceptable responses include, but are not limited to, this example: Identify the type of plate boundary or geologic feature found at location B. Acceptable responses include, but are not limited to, these examples: Mariana Trench trench convergent plate boundary subduction zone overriding plate subduction plate Which statement correctly describes the distance between the earthquake epicenter and these seismic stations? (3) C is closest to the epicenter, and A is farthest from the epicenter. When a continental crustal plate collides with an oceanic crustal plate, the continental crust is forced to move over the oceanic crust. What is the primary reason that the continental crust stays on top of the oceanic crust? (1) Continental crust is less dense. What will be the primary result of the continuation of the geologic processes indicated at this location? (4) New oceanic crust will form. Which type of crustal plate boundary is shown in this diagram? (1) divergent The dark-colored lava flows shown in the diagram were pushed from the magma chamber onto the surface of the ocean floor. Which characteristics are present in the solid rock that formed when the lava flows cooled? (1) generally small grain size and mafic composition Earth’s crust is described as “constantly shifting and moving.” Give one example of geologic evidence that supports the conclusion that continents have drifted apart. Acceptable responses include, but are not limited to, these examples: Continent shapes fit together like puzzle parts. Sea-floor spreading occurs at mid-ocean ridges. Bedrock can be correlated on the opposite sides of some oceans. Fossil evidence is found in the matching bedrock of South America and Africa. matching mountain ranges between continents The information given suggests that “subduction processes are the driving force of plate tectonics.” Identify a specific location of a subduction zone on Earth. Acceptable responses include, but are not limited to, these examples: west coast of South America Aleutian Trench boundary of Juan de Fuca Plate and North American Plate According to the Earth Science Reference Tables, at what inferred depth is mantle rock partially melted and slowly moving below the lithospheric plates? Any response from 70 to 700 kilometers. According to the geologic record, during which geologic time period did the lithospheric plates that made up Pangea begin to break up? Triassic Period The study of how seismic waves change as they travel through Earth has revealed that (4) Earth’s outer core is liquid because S-waves are not transmitted through this layer When did the first P-waves arrive at this seismic station? (2) 5 minutes after an earthquake occurred 2,600 km away How many additional seismic stations must report seismogram information in order to locate this earthquake? (2) two Which model most accurately shows the movements (arrows) associated with the surface features shown in the diagram? The hottest crustal temperature measurements would most likely be found at location (3) C Which table best shows the relative densities of the crustal bedrock at locations A, B, C, and D? Which graph best shows the relative age of the ocean-floor bedrock from location B to location C? Approximately how far away from station Y is the epicenter? (2) 2,600 km The S-waves from this earthquake that travel toward Earth’s center will (3) be absorbed by the liquid outer core Seismic station Z is 1,700 kilometers from the epicenter. Approximately how long did it take the P-wave to travel to station Z? (3) 3 min 30 sec On the map, which location is closest to the epicenter of the earthquake? (3) H–3 Mid-ocean ridges (rifts) normally form where tectonic plates are (2) diverging The motion of the convection currents in the mantle beneath the Atlantic Ocean appears to be mainly making this ocean basin (3) wider According to the diagram, the deep trench along the west coast of South America is caused by movement of the oceanic crust that is (1) sinking beneath the continental crust The photograph below shows an impact crater approximately 1 mile wide located in Diablo Canyon, Arizona. Describe the event that produced this crater. Acceptable responses include, but are not limited to, this example: Barringer Crater was caused by the impact of a meteorite (or meteor or comet or asteroid). Which cross section below best represents the crustal plate motion that is the primary cause of the volcanoes and deep rift valleys found at mid-ocean ridges? Most inferences about the characteristics of Earth’s mantle and core are based on (1) the behavior of seismic waves in Earth’s interior The distance from this seismic station to the epicenter of the earthquake is approximately (3) 4,400 km a What is a tsunami? b State how tsunamis can affect coastal regions. a Acceptable responses include, but are not limited to, these examples: large ocean wave or series of ocean waves generated by an earthquake wave caused by an earthquake Note: Accept the commonly used term tidal wave, but do not accept the response that tsunamis are caused by tides. b Acceptable responses include, but are not limited to, these examples: flooding bringing in sand deposits destruction of coastal property a Identify the tectonic plates on both sides of the plate boundary shown on the map. b Identify the type of tectonic plate boundary shown on the map that is responsible for the thrust faults along the Washington and Oregon coastline. a Allow credit for Juan de Fuca Plate and North American Plate. b Acceptable responses include, but are not limited to, these examples: subduction zone convergent plate boundary or Allow credit for a response that is consistent with the student’s answer for a. Note: Do not allow credit for thrust faults. Which statement best describes the cause of the ridges shown? (2) Some rock layers were more resistant to weathering and erosion. Deformed rock structure like this is most often caused by (1) crustal plate collisions If the earthquake occurred at exactly 10:00 p.m., approximately how far from the earthquake epicenter was Albany, New York? (3) 4,000 km Which seismogram was recorded approximately 4,000 kilometers from an earthquake epicenter? Which mantle hot spot is at a plate boundary like the one shown in this diagram? (3) Galapagos Hot Spot What are the names of the four tectonic plates located near the Nevado del Ruiz volcano? Allow credit if all four plates are correctly named. The correct responses are shown below. (1) South American Plate (2) Cocos Plate (3) Caribbean Plate (4) Nazca Plate What caused most of the destruction associated with the eruption of Nevado del Ruiz? Acceptable responses include, but are not limited to, these examples: mass movement of mud down the mountain a mud avalanche It melted snow, causing mudslides. Hot ash and pumice melted snow, creating landslides. What caused the magma to expand, blowing the magma plug free? Acceptable responses include, but are not limited to, these examples: a drop in pressure on the magma Steam and gases that were dissolved in the magma violently expanded. Cracks in Earth’s crust lowered pressure on the magma. Magma pressure cracked the overlying rocks, releasing the gases. Vesicular texture is very common in igneous rocks formed during andesitic eruptions. Explain how this texture is formed. Acceptable responses include, but are not limited to, these examples: Escaping gas bubbles are trapped in the rapidly cooling magma. Gas/air pockets form in the rock as it cools. Why are eruptions of Nevado del Ruiz generally more explosive than most Hawaiian volcanic eruptions? Acceptable responses include, but are not limited to, these examples: Hawaiian magma is mafic and the magma of the Nevado del Ruiz volcano is andesitic. Hawaiian magma is runny and the magma of Nevado del Ruiz is thick and slow moving. Hawaii is located at a hot spot in the center of the Pacific Plate. Nevado del Ruiz is near a subduction plate boundary. Describe one emergency preparation that may reduce the loss of life from a future eruption of the Nevado del Ruiz volcano. Acceptable responses include, but are not limited to, these examples: Geologists should monitor conditions and provide early warning. People should leave their houses when early warning of an eruption is given. Avoid building homes in valleys. People should be discouraged from building near the volcano. Evacuation routes should be publicized. Predicted mudslide routes should be identified. Approximately how long does an earthquake P-wave take to travel the first 6500 kilometers after the earthquake occurs? (3) 10.0 min What are the two most abundant elements by mass found in Earth’s crust? (4) oxygen and silicon At point A, the East Pacific Ridge is the boundary between the (4) Pacific Plate and the Nazca Plate At which drilling site would the oldest igneous bedrock most likely be found? (1) 1 Compared to the thickness and density of the continental crust of South America, the oceanic crust of the Pacific floor is (2) thinner and more dense At which city is there a difference of approximately 3 minutes and 20 seconds between the arrival times of the P-waves and the S-waves? (1) New Orleans Which map correctly shows how the location of the epicenter was determined? This diagram provides evidence that the Pacific Crustal Plate was moving toward the (4) northwest The arrows shown in the asthenosphere represent the inferred slow circulation of the plastic mantle by a process called (2) convection The temperature of rock at location A is approximately (3) 2,600°C Which process was primarily responsible for forming the hills? (2) faulting Which graph best represents the geologic age of the surface bedrock on the ocean bottom? Tectonic plate boundaries may be classified as divergent, convergent, or transform. For each location listed in the data table below, place an X in the proper column to indicate the type of plate boundary at that location. Allow credit if three or four boundaries are identified correctly. A seismic station in Massena, New York, recorded the arrival of the first P-wave at 1:30:00 (1 hour, 30 minutes, 00 seconds) and the first S-wave from the same earthquake at 1:34:30. a Determine the distance, in kilometers, from Massena to the epicenter of this earthquake. b State what additional information is needed to determine the location of the epicenter of this earthquake. a Allow credit for 3,000 km (±200 km). b Allow credit for data from two additional seismic stations. Identify the direction toward which the ash cloud spread from April 5 to April 25. Acceptable responses include, but are not limited to, these examples: toward Asia (Africa) westward across the Pacific Ocean State what caused the main ash cloud to spread in the pattern shown on the map of April 25, 1982. Acceptable responses include, but are not limited to, these examples: prevailing or planetary winds the spin of Earth and the Coriolis effect on wind direction State the most likely effect of the ash cloud on the temperature of areas under the cloud on April 25, 1982. temperatures decreased As the ash cloud moved away from El Chichón, some ash particles fell back to Earth. a Describe how the size of the particles affected the pattern of deposition. b Describe how the density of the particles affected the pattern of deposition. a Acceptable responses include, but are not limited to, this example: Larger particles fell closer to the volcano. b Acceptable responses include, but are not limited to, this example: More dense particles fell closer to the volcano. According to the graph, what is the approximate number of days each year that thunderstorms occur at locations along the 40° N parallel of latitude? (1) 8 days Andrija Mohorovičic´ discovered the interface between the crust and the mantle that is now named for him. His discovery of the “Moho” was based on analysis of (4) seismic waves The observed difference in density between continental crust and oceanic crust is most likely due to differences in their (1) composition Which diagram correctly shows how mantle convection currents are most likely moving beneath colliding lithospheric plates? Model A best represents the motion of earthquake waves called (1) P-waves (compressional waves) that travel faster than S-waves (shear waves) shown in model B The difference in seismic station arrival times of the two waves represented by the models helps scientists determine the (3) distance to the epicenter of an earthquake Which graph best shows the depth of earthquakes beneath epicenters A, B, C, and D? The earthquake beneath epicenter D occurred in which part of Earth’s interior? (3) asthenosphere On the chart provided below, write the information that should be placed in the boxes labeled A, B, and C that will correctly complete those portions of the concept map. Allow credit if all three answers are correct. Acceptable responses include, but are not limited to, these examples: On the geographic map provided below, write the letters D and E on the plate boundary locations where the indicated movements are occurring. Write the letters approximately the same size as shown on the concept map and locate the letters directly on the plate boundary. Allow credit for writing the letter D on any transform plate boundary. Student answers locating D over major transform ocean-ridge faults should also be accepted for credit and for writing the letter E on any subduction plate boundary between an oceanic plate and a continental plate. The diagram below shows examples of locations where the letters D and E could be placed. The Peru-Chile Trench marks the boundary between the (2) Nazca Plate and the South American Plate In which diagram do the arrows best represent the motions of Earth’s crust at the Peru-Chile Trench? Which observation provides the best evidence of the pattern of crustal movement at the Peru-Chile Trench? (4) the locations of shallow-focus and deep-focus earthquakes Approximately how far has location X moved from its original location over the hotspot? (3) 1,800 km According to the data table, what is the approximate speed at which the island of Kauai has been moving away from the mantle hotspot, in kilometers per million years? (3) 100 Which lithospheric plate boundary features are located at Y and Z? (1) trenches created by the subduction of the Pacific Plate Which type of crustal movement most likely caused the displacement of features in this area? (4) movement along a transform fault The tilted rock structure shown in the photograph is most likely the result of the (4) collision of crustal plates Tilted, slightly metamorphosed rock layers such as these are typically found in which New York State landscape region? (1) Taconic Mountains Which time scale best represents the arrival-time difference between P-waves and S-waves at this station? The cross section below shows the lithosphere and asthenosphere between points A and B on the map. a On the cross section provided below, draw an arrow in the Juan de Fuca Plate to indicate the direction of the relative movement of the plate. b Identify the type of tectonic plate boundary that exists at the Juan de Fuca Ridge. c Identify the name of the plate in the cross section labeled x. d How does the average earthquake depth beneath the Oregon coastline compare to the average earthquake depth beneath Mt. Hood? a Allow credit for correctly drawing an arrow in the direction of the relative movement in the Juan de Fuca Plate. Student answers should appear generally like the diagram. b divergent or mid-ocean ridge plate boundary. c Pacific Plate. d Acceptable responses include, but are not limited to, this example: Earthquakes along the Oregon coastline are not as deep as earthquakes that occur beneath Mt. Hood. An emergency management specialist in Portland, Oregon, is developing a plan that would help save lives or prevent property damage in the event of a future earthquake. Describe two actions or ideas that should be included in the plan. Acceptable responses include, but are not limited to, these examples: plan evacuation routes identifying relative earthquake hazard zones or areas that are subject to damage during an earthquake plan emergency communication procedures (radio broadcast) developing emergency information brochures store food, supplies, and fresh water build earthquake-proof structures practice emergency rescue drills identify shelter locations A huge undersea earthquake off the Alaskan coastline could produce a (1) tsunami What is the most probable reason for the absence of S-waves at station A? (1) S-waves cannot travel through liquids. What is the approximate distance from station C to the earthquake epicenter? (3) 1,600 km How long did it take the P-wave to travel from the epicenter of the earthquake to seismic station D? (4) 00:09:40 What is the most probable age, in millions of years, of the bedrock at location B? (3) 48 Rising convection currents in the asthenosphere would most likely be under location (3) C The age of oceanic bedrock on either side of a mid-ocean ridge is supporting evidence that at the ridges, tectonic plates are (1) diverging Explain why Portland is likely to experience a major earthquake. Acceptable responses include, but are not limited to, these examples: Tectonic plates are shifting in this region. The ancient faults detected under Portland may still be active. Soft sediment causes minor earthquakes to become major earthquakes. Portland is located near a plate boundary. Note: Do not allow credit for hot spot. Why is the presence of a layer of silt and mud deep under the city a danger to Portland? Acceptable responses include, but are not limited to, these examples: Soft sediment can amplify earthquake ground movement. Buildings can be damaged by liquefaction within those sediments during the earthquakes. Structures can collapse, tilt, or sink during an earthquake. Describe one precaution that can be taken to prevent or reduce property damage in preparation for a future earthquake in Portland. Acceptable responses include, but are not limited to, these examples: Reinforce buildings to provide greater stability. Make buildings more flexible. Redesign or reconstruct highway overpasses. Rewrite or enforce strict building codes. Restrict building in surface areas identified as more susceptible to earthquake damage. What type of tectonic plate boundary is shown at the San Andreas Fault? transform plate boundary or transform fault or transform. Note: Do not allow credit for faulting, fault, or hot spot.
