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DYNAMIC PLANET: EARTHQUAKES, VOLCANOES, AND PLATE TECTONICS Scrimmage 2009 PART 1: The Structure of the Earth 1. The soft weak structural layer 'weak zone' of the earth's mantle that is actually capable of flow is called the aesthenosphere . The rigid sphere of rock situated just above it is called the lithosphere. Both of these layers would be considered compositional or mechanical layers of the earth? 2. The most prominent mountain range on the Earth is the Himalayas . By contrast, narrow deep troughs in places more than 11,000 meters deep, occur in the sea floor adjacent to volcanic islands and young mountain chains on the edges of continents. These deep narrow troughs are called trenches ? . 3. According to the theory of plate tectonics , the rigid lithosphere of the Earth is broken into numerous segments called plates . The three distinct types of boundaries between these segments of rigid lithosphere are known as convergent boundaries, divergent , boundaries, and transform boundaries. 4. As new oceanic lithosphere is created at the ocean ridges, the old oceanic lithosphere is pushed aside. This process is called sea floor spreading and occurs at a rate of 5cm per year (label units properly). This is an excellent example of which type of boundary? divergent 5. Stable continental interiors are known as shields and are largely composed of granite The age of rocks in these areas are some of the oldest known on earth and are roughly 3.8 billion years old. 6. Regions where the oceanic lithosphere is being consumed and melted are called subduction zones . . 7. Along most continental coasts a gently sloping platform extends seaward from the shore and is called the continental shelf. At the seaward edge of such platforms a steep drop off, called a continental slope occurs. 8. Review the following characteristics and associate them with one of the compositional layers of the earth: crust mantle or core. a. core b. mantle c. crust d. mantle e. core 2009 Mentor Invitational composed mostly of iron with some nickel and other elements over 80% of the earth's volume is in this compositional layer typically thin and composed of igneous rocks like granite and basalt although it behaves like a solid when transmitting earthquake waves it actually flows it is compositionally very dense (11 g/cm3) and yet its outer layer is capable of flow while the inner layer behaves like a solid. It's rotation generates the earth's magnetic field. -1- dynamic planet 9. As you go deep into our planet the pressure and temperature rise, radioactive elements decay releasing heat deep in the core. The only way the interior of the earth can transfer its internal heat to space is through a process called convection , where hot materials rise, move laterally, cool and then descend again. 10. Long before the continents began to drift apart they were joined together in a super continent called: a. wonderland b. Atlantis c. Pangea d. Gondwanaland James Porter would pick this but you shouldn’t! 11. Which of the following is true about the lithosphere? a. It is the relatively solid outer layer of the earth b. It is generally 100 km thick sometimes more sometimes less c. It is composed of basaltic and granitic rocks d. all of the above 12. Which of the following is true about the asthenosphere? a. It is a relatively weak zone of the earth's layers b. It is only very slightly melted (1-5%) c. It is plastic d. all of the above e. a and c 13. For each of the following statements indicate true or false. a. true The densest portion of the earth is the mantle b.false Shields and ocean floors are the oldest rocks on the planet at about 3.8 billion years old. c. true The density of continental rocks is generally less than the density of sea floor rocks d. true The San Andreas Fault of California is a transform boundary e. false When continents collide, subduction happens rapidly f. true Some of the oldest mountains in the world are the Urals and the Appalachians while the youngest mountains are those forming around the ring of fire g. true The formation of mountain ranges in the pacific Northwest is due to subduction of oceanic crust under the continental crust. 14. Isostacy is the principal that explains why Greenland has been deformed by some 11,000 feet of glacial ice and is now rebounding as the ice melts. It is the plastic flow of the asthenosphere that allows this process to occur. 15. Which of the following help to explain magnetic striping of the basaltic ocean floor? a. Periodic reversal in the earth's magnetic field b. divergent boundary of the mid Atlantic rift c. convection currents in the asthenosphere create magnetic anomalies d. all of the above e. a and b 2009 Mentor Invitational -2- dynamic planet 16. It was the fit of the shape of South America and Africa that initially lead Alfred Wegner to consider the possibility of continental drift, true or false? true 17. The ocean crust at the mid Atlantic ridge is less dense that oceanic crust that is further east or west of the ridge, true or false? true 18. Hugo Benioff studied earthquake foci along the west coast of South America. He discovered that the foci are quite shallow near the oceanic trench west of South America and that as you move east, the earthquake foci become deeper . . 19. Some volcanoes tend to erupt very violently or explosively while other volcanoes such as those in Hawaii, tend to erupt quietly and create massive flows of lava . . 20. The Mariannas Trench is the deepest part of the Ocean and represents a zone of subduction. 21. Identify each of the following statements or descriptions with a number from the drawing below. This layer includes both the more bouyant felsitic rocks and the denser basaltic rocks that compose the earth as humans see it. (1) This layer is composed of intensely hot nickle and iron (3 or 3a & 3b) This layer is composed of materials rich in iron, magnesium and calcium (2) This layer includes the aesthenosphere and both layers of the mantle (2) Aesthenosphere (5) Outer core (6) Inner core (7) Lithosphere (4) 2009 Mentor Invitational -3- dynamic planet 22. The most massive volcanic explosion in the last 25 years in the United States was the eruption of Mt St. Helens and is caused by the rising plutons of melting magma from the subduction of oceanic crust under continental crust. Part 2 VOLCANOES 23. It is well known that the explosiveness of a volcanic eruption is directly correlated with the viscosity of the magma associated with it. Which of the following factors affect the viscosity of magma? a. temperature b. Silica content c. thickness of overlying crust d. dissolved gas content e. all of the above f. a, b, and d g. a and b 24. Basaltic or mafic magma tends to be more viscous and has a silica content of roughly 50% while Felsic Lavas have a silica content of roughly 70% and tends to flow freely, true or false? 25. Magma with more gas content tends to erupt explosively as gas is released, true or false? 26. The more fluid, low silica content basaltic flows tend to let dissolved gasses escape and allowing for a more quiet eruption, true or false? 27. Complete the following table; composition silica content mafic or basaltic magma Andesitic magma Felsic or granitic magma viscosity gas content pyroclastic tendency volcanic landform 50% least least 1-2% least Shield cones basalt plateaus cinder cones 60% intermediate Intermediate 3-4% intermediate Composite cones 70% most most 4-6% greatest Volcanic dome pyroclastic flow 28. The most prominent gas in magma is water vapor. Other important gases in magma are carbon dioxide , nitrogen ,sulfur dioxide . 29. When basaltic volcanoes flow, they produce unique types of lava called 2009 Mentor Invitational -4- dynamic planet a. aa b. pahoehoe c. tahaha d. pillow lava e. a, b, and d f. a and b 30. When Felsic magmas, highly charged with gasses and very viscous, erupt from a volcano they tend to release pulverized rock, lava and glass fragments from the vent. Equally gasses propel basaltic magma high into the air launching incandescent blobs of lava that cool and fall around the vent. All of these materials ejected from the volcano are collectively called a. pyroclastics b. ash flows c. cinders d. a big mess 31. Viscous eruptions also release ash and dust during explosions. These fine glassy fragments fall and fuse to form an incredibly light volcanic rock that can float on water. What is this rock called? Pumice 32. Rank the following volcanic ejecta by size from smallest to largest, bombs, lapilli, blocks, and cinders.lapilli cinders, blocks and bombs 33. Mauna Loa is a fine example of a shield volcano. 34. Rank the following volcanic cones by size from largest to smallest, cinder cones, composite cones, shield volcanoes. Shield, composit, cinder 35. mars What is the biggest volcano in our solar system, where is it found?olympus mons on 36. The majority of the volcanoes found in the ring of fire are what type of volcanic cone? What is another name for this type of volcano. Composite/ stratovolcano 37. Mount Vesuvius is responsible for the destruction of the ancient Roman city below it called Pompeii . Here an especially dangerous type of pyroclastic flow called Nuee Ardente a (glowing avalanche) engulfed the city and cast the inhabitants in stone. These pyroclastic flows are known for their speeds of 200 kph. 38. Another dangerous attribute of composite cone eruptions are the massive mud flows that can develop that are called lahars . 39. Many volcanoes have steep walled craters which are called caldera when it exceeds 1 km in diameter. These are caused by the collapse of the magma chamber following an eruption. 40. As very viscous lava is forced out of a vent it may produce a raised mass of congealed lava called a lava dome. Would you expect these to develop in the Hawaiian Island volcanoes? No the lava is not viscous enough 41. A huge land form in the western United States is the Columbia Plateau a lava flow that is nearly 200,000 square km with an average thickness of 1 km. What type of magma would you suspect formed this land form? basalt 2009 Mentor Invitational -5- dynamic planet 42. Large masses of magma deep in the earth are called plutons, named for pluto, god of the lower world. As magma in these plutons seeps vertically and horizontally through fissures in overlaying rock layers they solidify to form land forms we call dikes if they cut across layers of overlying rock and sills if the run between overlying layers of rock. However the largest intrusive igneous bodies are batholiths, hundreds of km long and up to 100 km wide and they form as plutons merge. 43. The presence of volcanic activity is not randomly spread around the globe instead it tends to be concentrated at zones of convergence and divergence. . 44. Match the following: a. Aleutian Island Volcanoes 3 1. intra plate continental volcanism b. Yellow Stone hot spot 1 2. oceanic divergence c. Mid oceanic Ridge 2 3. Subduction Zone volcanism d. Hawaiian Hot Spot 4 4. intraplate oceanic volcanism e. Andes Mountains 3 5. continental divergence f. African Rift zone 5 45. Is it possible for volcanoes to change earth's climate? How? If so, would it tend to increase or decrease the earth's mean temperature? Yes, ejects particulates into stratosphere blocking light and reducing the temperature of earth. 46. What was the name of the biggest eruption in the last 2000 years?Tambora 47. In the image to the right you see a cylindrical body of rock standing above the surrounding terrain after the rest of the volcano has been eliminated by erosion. This is called a volcanic neck . Now look at the image to the left. Is it the same geologic structure as the image below (yes or no)? Why do they look so similar? No, they look the same because they are both formed of columnar basalt. It is a lava flow that cooled slowly. 2009 Mentor Invitational -6- dynamic planet 48. Study the profiles of the following volcanic cones and indicate which is a cinder cone, which is a shield volcano, and which is a stratovolcano.? a.cinder b.shield c. composit/stratovolcano 49. What are the three main factors that determine the nature of volcanic eruptions? Gas content, silica content and temperature 50. Granitic plutons located near subduction zones are probably produced mainly by which of the following: a. hot spot activity b. partial melting of water-rich materials that were subjected to high temperatures c. fractional crystallization of magma produced by partial melting in the subduction zone d. fractional crystallization of magma from deep within the earth mantle PART THREE: EARTHQUAKES 51. The vibration of the earth produced by the rapid release of elastic energy stored in the earth’s rocks is called an earthquake . . 52. What is the difference between the focus of an earthquake and the epicenter? The epicenter is on the surface the focus is the actual center of the earthquakes origin 53. The shock waves that occur after an earthquake are called aftershocks , while the shock waves that precede an earthquake are called foreshocks . 54. The study of earthquake waves is called seismology, true or false? 55. The recordings obtained from a seismograph are called what?seismogram 56. During an earthquake, some waves travel along the earth's surface and are therefore called surface waves. Others travel through the earth and are called body waves. Body waves are further divided into two types of waves, what are they? P or primary and s or secondary waves 57. P waves are compressional and can travel through solids, liquids, and gasses, and change the volume of intervening materials in the direction of their travel, true or false? 58. S waves on the other hand are Shaking waves and temporarily change the shape of materials at right angles to the direction of their travel. Fluids and gasses will not transmit S waves, true or false? 59. Which wave type travels faster through rock? P or primary How much faster?1.7 x 60. Surface waves travel at 90 percent of the velocity of an S wave, true or false? What is another name for these surface waves?long waves 2009 Mentor Invitational -7- dynamic planet 61. By measuring the time between the first P wave and the first S wave and using that information on the time travel graph we can determine what? a. distance from the focus b. direction to the focus c. distance from the epicenter d. direction to the epicenter e. c and d f. a and b 62. By triangulating the distance from three (a number) recording centers, the epicenter of the earthquake can be determined. 63. In order to know the focus of an earthquake you need to know not only the epicenter but the depth below the surface. 64. The Benioff Zone is a seismic region near a trench that has increasingly deep earthquake foci as you move away from the trench and indicates the direction of movement of the subducted crust true or false? 65. Earthquake intensity is measured on the Mercalli Intensity Scale, and assesses the damage from a quake at a specific location, but is not really predictive of the innate strength of an earthquake. 66. The amount of damage caused by an earthquake depends on which of the following: a. Strength of the Quake b. distance from the epicenter c. nature of the surface (rock, sand, soil?) d. building codes e. all of the above 67. Since Earthquake intensity is somewhat unrelated to just the strength of the earthquake we now use a scale that ranks quakes by magnitude which is called the Richter Scale. This scale is a linear scale or a logarithmic scale? (choose one). Each unit in this scale relates to a ten (number) fold increase in energy released and a 32 fold (also a number) increase in the amplitude of the S wave. 68. One of the most dangerous and destructive effects of an earthquake has to do with the effect of ground motion on water. Seiches are the rhythmic sloshing of water in lakes and reservoirs and bodies of enclosed basins like the Gulf of Mexico. Name another devastatingly dangerous water-earthquake related phenomena that can devastate shorelines hundreds of miles from an earthquake.Tsunami 69. Although these huge waves can travel in the open ocean virtually undetected as a small swell and at extremely great speeds (800 kph) as they approach the continental shelf, they slow down and increase in height dramatically. 70. Land slides, ground subsidence and Fire are also great earthquake hazards. What great American Earthquake suffered from fire? What other great American Earthquake suffered from Tsunami and liquefaction of the ground? San Fransisco earthquake and Alaska earthquake of 64 2009 Mentor Invitational -8- dynamic planet 71. Examine the Seismogram below and note the features labeled A through G. On the lines provided beside each item shown below (a-d) note the letter A through G that corresponds to that item a.c an S Wave b.g the first P wave c.c a surface wave d.d the first S wave e.b an L wave PART FOUR: PLATE TECTONICS 72. Alfred Wegener is the 'father' of continental drift and he suggested a primordial supercontinent called Pangea . . 73. Which of the following were early evidence of continental drift? a. fit of the continents b. fossil record c. rock types e. paleoclimatic evidence d. all of the above 74. The temperature that when a magnetized mineral is heated above, it will lose its magnetism is called the Curie point, true or false? 75. More current evidence for continental drift includes which of the following a. paleomagnetism b. sea floor spreading c. geomagnetic reversals d. Polar wandering e. mid-oceanic magnetic stripes f. all of the above 76. Name the three types of plate boundaries convergent divergent and transform 77. Name as many plates as you can think of. Antarctic African Eurasian Australian, Indian, Phillippine, Pacific, North American, Juan de Fuca, Nazca, Coscos, Carribean, south American, Scotia 78. Name two divergent boundaries, one in the Pacific Ocean and one in the Atlantic Ocean. Mid atlantic ridge, East Pacific Rise 79. Sea floor spreading is a result of what type of plate boundary?divergent 2009 Mentor Invitational -9- dynamic planet 80. If a divergent boundary occurs on a continent, what geologic feature is created? Can you name one that exists in Africa? Rift Valley East African Rift Valley 81. At divergent boundaries new crust is being made or destroyed? made 82. At convergent boundaries continental crust is being made or destroyed? What is the name of the zone where this is occurring? Made, subduction zone 83. As two plates collide, what determines which will go under and be subducted? density 84. As crust is subducted down into the asthenosphere, the foci of earthquakes follows the subducted crust and becomes (shallower or deeper). 85. As oceanic crust is subducted under oceanic crust what feature appears in the oceanic crust over the subducted plate and runs parallel with the oceanic trench?island arc 86. When continental crust collides with continental crust neither will subduct below the other because of the low density and buoyant nature of continental rock. What geologic feature appears and runs parallel with the boundary between the colliding plates? Give an example.mountains Himalayas 87. When oceanic crust is subducted below continental crust there is an accumulation of deformed sediment and scraps of oceanic crust called an accretionary wedge that add to the mass of the continent. 88. The plate boundary characterized by strike-slip faulting where plates grind past each other is called?transform boundary 89. Examine the image to the right. Here an isolated point exists where magma is upwelling from the mantle and creating a chain of oceanic volcanoes. This point is called a hot spot . If the top of your page is north, then what direction is the oceanic plate moving?Northwest 2009 Mentor Invitational - 10 - dynamic planet PART FIVE: JUST FOR THE FUN OF IT! 90. Identify the image to the right. How is it formed? This is a caldera. You can tell because it is huge, notice the quadrangle markings. It is formed when, after an eruption the magma chamber below is emptied and finally collapses in on itself. 91. In the image to the left, the darkened area is not lava but constitutes a significant volcano hazard. What is it, and how is it formed? It is a lahar, formed when snow and ice are rapidly melted during an eruption and mixed with debris forming a quick moving and sometimes hot mud flow. 92. The image to the right shows damage to a building caused by an earthquake. What geologic process caused this type of failure? This type of tipping of buildings during an earthquake is caused by a type of ground failure called liquefaction. 93. In the image to the left some foolish person stopped long enough to snap this picture. What was he looking at? What should he be doing? Just moments before this picture was taken people sunbathing on the beach noticed something unusual that could have saved their lives, what? This is a tsunami, he should be running for his life, the ocean went out away from shore only to return with a vengance 2009 Mentor Invitational - 11 - dynamic planet a 94. In the image to the left, which set of images illustrate Body waves (choose all that apply)? Which illustrate Surface waves (choose all that apply)? Identify the specific type of wave by name for a through d b a & b are body waves, while c and d are surface waves. A is a P wave, B is a S wave, C is a Love wave, D is a rayleigh Wave c d 95. In the image to the right you see one of the most frightening things that can happen to you if you are near a volcanic eruption. What is it and how fast can it go? Instead of stopping to snap this photo, what should the photographer really be doing? This is a nuée ardente. Rapidly moving volcanic pyroclastic that will burn you alive. It can travel at speeds up to 200 kph. Running for his life. 96. In the image to the left this is by a single member of a group of oceanic islands near the Marianas Trench. It is a beautiful example of what type of volcanic formation (not type of volcano) ? If we were flying into this area to observe the eruption what hazard should we be most concerned about? volcanic Island arc. planes 2009 Mentor Invitational - 12 - Ash – it can down dynamic planet 97. In the image to the right identify the type of basalt? What makes it form this way? Columnar basalt, very slow cooling so large basaltic crystals can form. 98. In the image to the left you see a very thick volcanic deposit several hundred feet thick. This deposit is the result of a pyroclastic flow of very fine grained materials ejected during a volcanic eruption that rides on a cushion of air until it begins to cool and the particles become welded into this rock formation. What is it? tuff 99. Dr. Anne and her band of wild science Olympians were camping on the edge of this lake. All day they had felt small earthquakes coming from the lava dome in the middle of the lake. They were taking meticulous measurements at all the nearby surface water gauging stations at the mouths of streams when a particularly large quake occurred. Casey O’donnell noticed something funny on the lake’s surface (see the image below). He pointed it out to Dr. Anne who took her time snapping a run! picture and then calmly yelled What in the world did they see? Seismic seiche the end, thank goodness! 2009 Mentor Invitational - 13 - dynamic planet 2009 Mentor Invitational - 14 - dynamic planet