Download Review for Earthquakes Test

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Earthquakes & Volcanoes Study Guide
Just completing this study guide is not sufficient. You will also need to study all labs, readings, and your journal.
Lesson 11 – P-waves and S-waves
1. What can be done to make buildings more earthquake safe?
- A foundation firmly connected to solid bedrock.
- Beams and columns strapped together and to the ground with metal, and the floors and roofs are
securely fastened to the walls.
- Brick houses and buildings may be sprayed with liquid concrete and reinforced with steel bracing.
2. How does the type of ground material affect the amount of shaking during an earthquake? Be specific…know when
the ground will shake the most/least.
Moist soils, especially those rich in clay, and loose soils like sand, lose their compactness during an
earthquake. Parts of the soil rotate, acting more like a liquid or gelatin than a solid surface. In earthquake
prone areas, steel posts are driven deep into the solid bedrock to create a secure foundation for the
building.
3. Which waves travel through the body of the earth?
P-waves and S-waves are body waves meaning they travel through the body of the earth.
4. What does the ‘p’ in p-wave stand for?
Primary – these waves arrive first.
5. What does the ‘s’ in s-wave stand for?
Secondary – these waves arrive second.
6. Which wave is the fastest?
P-wave
7. How does each of the 3 waves affect the movement of the ground on the surface?
The p-waves cause vertical (up and down) jolting of the earth’s surface. S-waves cause horizontal (side to
side) movement of the earth’s surface. Some surface waves produce an up and down rolling motion like the
motion you feel when on a boat, while other surface waves move material from side to side.
8. List the waves in order from least destructive to most destructive.
(Least) P-waves, S-waves, Surface waves (Most)
Lesson 12 – Recording Vibrations on Seismograms, with Seismometers and Seismographs
1. What is the focus of an earthquake?
The focus is the point where the earthquake actually occurs (the site of energy release), it can be shallow
or deep in the earth.
2. What is the epicenter of an earthquake?
The epicenter is the point on the earth’s surface directly above the focus. It is usually the place you hear
about in the news when there has been an earthquake.
Skills:
3. Know how to use a seismogram to find the time that the p-wave and the s-wave first arrived at the seismograph
station. (You WILL have to do this on the test.)
4. Know how to find the epicenter of an earthquake if you have earthquake data from 3 different seismograph stations.
(You WILL have to do this on the test.)
5. Know how to find the distance of a location from the epicenter of the earthquake.
(You WILL have to do this on the test.
Lesson 13 – Plotting Earthquakes
1. What does magnitude measure?
Magnitude is determined by measuring the amplitude, or “swing” of the largest seismic wave on the
seismogram. Magnitude measures the total amount of energy released at the focus of the earthquake. A
magnitude 7 earthquake release the same amount of energy always, though the effects might differ based
on where the earthquake occurs.
2. What scale is traditionally used to measure magnitude? Richter Scale
3. Each increase in magnitude number represents a 10-fold increase in energy released.
4. What does intensity measure?
Intensity measures the type of damage done by the earthquake as well as people’s reactions to the
earthquake. It is a measure of the effect of an earthquake on the structures, people and environment. The
intensity of an earthquake may vary depending on where it occurs.
5. What scale is used to measure intensity? Modified-Mercalli Scale
6. What do the locations of earthquakes and volcanoes have in common?
Earthquakes and volcanoes both tend to occur along plate boundaries. The most common area for
earthquakes and volcanoes worldwide is the Ring of Fire (The Circum-Pacific Belt). The Ring of Fire is a
nearly continuous chain of volcanoes around the edges of the Pacific Ocean.
7. What can the locations of earthquakes around the world tell us about the earth’s surface?
Because the locations of earthquakes tend to be along plate boundaries, we can tell that the earth’s surface
is broken into plates that move relative to one another. We can infer the location of plate boundaries by
looking at historical earthquake activity which traces the plate boundaries on earth.
Lesson 14 – Using Earthquakes to Study the Earth’s Interior
1. Draw a diagram and label the inner core, outer core, mantle,
and crust.
2. How do scientists know the inside of the earth is made of layers?
Scientists analyze seismic waves to study the inside of the earth. As the earthquake waves move through
the different layers of the earth, they change speed and direction based on the properties of that layer.
3. What is one way that scientist know the outer core is liquid?
S-waves cannot travel through liquid, because S-waves also do not travel through the outer core, scientists
can infer that the outer core is liquid.
4. Describe the lithosphere and the asthenosphere.
Asthenosphere
- Upper mantle
- Hot, weak
- Can move
Lithosphere
- Includes the upper mantle and the crust
- Continental and oceanic crusts
- Ridged, solid
- Floats on the asthenosphere
Lesson 15 – Investigating Plate Movement and Faults
Skills:
Know the names and locations of the Earth’s major tectonic plates
1. Draw and label a picture of a transform boundary, convergent boundary, and divergent boundary. Label the
features that are formed at each boundary.
Transform:
No land is created or destroyed as the two plates slide past one another.
Example: San Andreas Fault
Convergent:
When a continental and oceanic plate collide, the
oceanic plate subducts below the continental
plate forming a trench at the subduction zone.
Parallel to the subduction zone a volcanic
mountain range forms as some of the molten rock
from the mantle moves to the Earth’s surface.
When two oceanic plates collide, the older
(more dense) oceanic plate subducts below
the newer (less dense) oceanic plate forming a
trench at the subduction zone. Parallel to the
subduction zone a volcanic island arc forms as some of the molten rock from the mantle moves to
the Earth’s surface.
When two continental plates collide, neither
subducts under the other because they have
very similar densities. Instead the land folds
upward forming a mountain range (not
volcanic).
Example: The Himalyas (Eurasia and Indian
Plate colliding) and The Pacifc Plate
Subducting Under the North American Plate
Divergent:
At a divergent plate boundary, two plates are moving apart
as they do a rift valley is first formed, as the plates spread
further apart, the rift valley fills in with water eventually
forming a new ocean. Where the plates are moving apart,
magma from the mantle comes to the surface, cools and
hardens forming new seafloor.
Example: The Mid-Atlantic Ridge
Lesson 16 – Convection in the Mantle
A. Explain the evidence for Continental Drift Theory (evidence for Pangaea).
- Proposed by a German scientist named Alfred Wegener, the continental drift theory states that the
plates are constantly moving relative to one another.
- Evidence supporting the continental drift theory comes from:
o Fit of Plates
o Fossil Evidence
o Evidence from Rocks
o Climatic Evidence
- The mechanism for plate movement comes from
convection currents in the mantle. When a
convection cell rises in the mantle, it pulls the
plates with it and creates spreading centers
(divergent plate boundaries). When the cell
descends cold ocean lithosphere subducts into the
mantle and trenches form (convergent plate
boundaries).
Lesson 18 – Introducing Volcanoes
1. What are the warning signs that a volcano may erupt?
Earthquakes, vent clearing phases, gasses released, visible movement of magma under the surface.
2. What are 5 destructive effects of a volcanic eruption?
Death by suffocation, being hit by debris or being caught in the flow of debris and molten rock, knock down
forests, cause fires, destroy homes, roads, other infrastructure and landscapes.
3. What are 4 constructive effects of volcanic activity?
Hot springs as tourist attractions and recreation sites. Use of geothermal energy to heat and power homes,
businesses and greenhouses. Basalt, forms from cooled lava and is used for a variety of industrial and
chemical uses, it also forms the seafloor. Volcanic ash enriches the soil and is a source of nickel, chromium,
platinum and other important elements. Obsidian was used by the Native Americans in hunting and is used
today for fine stone work. Volcanoes create beautiful landscapes.
Lesson 19 & 20 – Volcanoes Change The Landscape/Viscosity and Volcano Type
1. What is the difference between magma and lava?
Magma is molten rock within the mantle (below Earth’s surface), lava is molten rock that has reached Earth’s
surface.
2. What is viscosity?
The ability of a liquid to resist flow. Something that is very viscous flows slowly, something with low viscosity
(less viscous) flows quickly like water.
3. Explain how lava/magma viscosity affect the type of volcano that is formed?
Runny lava (low viscosity) flows longer distances before hardening, it forms large, flatter volcanoes like shield
volcanoes. Thick sticky lava (high viscosity) forms tall, steep sided volcanoes like composite volcanoes
because it doesn’t flow as far before it hardens.
4. How are volcanoes formed at convergent plate boundaries?
At a convergent plate boundary, the oceanic plate (or the older plate if both are oceanic) subducts underneath
the other. When it subducts into the mantle it melts into magma. The magma rises to the surface where it cools
and hardens on land to form rock. Many successive layers of hardened magma build up to form a volcano.
Example: The Cascade Range and the Andes Mountains
5. How are volcanoes formed at divergent plate boundaries?
At a divergent plate boundary magma oozes to the surface as two plates spread apart. The magma cools and
hardens forming rock. Many successive layers of hardened magma build up to form a volcano.
Example: The Mid-Atlantic Ridge
6. How does a hot spot form a series of volcanoes?
A hot spot is a high temperature plume of magma that rises from the mantle and melts through the overlying
crust to form volcanoes. As plates move over the hotspot, magma rises to the surface and cools to form rock.
Many successive layers of hardened magma build up to form a volcano. As the plates move the older
volcanoes are carried away and newer volcanoes form.
Example: Hawaii
7. Describe and draw the three different types of volcanoes (How they form, what they are made of, shape…)
Shield
Shape - Wide and short
Size – Large, very wide
Lava – Low viscosity (very thin, runny lava
Eruptions – Quiet and gentle like a fountain as the lava oozes from the volcano
Formed near hotspots and fissures (cracks in the earth’s surface).
Examples – Iceland, Hawaiian Islands
Cinder Cone
Shape – Tall and narrow
Size – Shorter than composite volcanoes/taller than shield volcanoes, but less wide
Lava – Hard rocky lava
Eruptions – Very explosive and violent eruptions compared to shield volcanoes (less explosive
than composite).
Formed next to composite volcanoes along subduction zones.
Examples – Eldfell in Iceland, Sunset Crater
Composite
Shape – Tall and pointed, can be wider than cinder cone volcanoes. Iconic mountain shape.
Size – Very large.
Lava – Sticky, thick, high viscosity lava.
Eruptions – Sticky lava traps a lot of gases so the eruptions are very explosive and violent, but
eruptions occur less often.
Formed along subduction zones.
Examples – Mt. St. Helens, Mt. Fuji
8. Compare the three types of volcanoes (which is widest, which is tallest, which has the most explosive eruptions, which
has the least explosive eruptions)
Shield volcanoes are the widest, but tend to be shorter than the other types. Composite volcanoes are the
tallest and form nice iconic mountains with pointy tops. Because they have thick sticky lava that traps a high
amount of gasses, composite volcanoes have the most explosive eruptions while shield volcanoes tend to
have more oozing clam eruptions (think Mauna Loa).
Lesson 23 & 24 – Volcanic Ash/The Effects of Ash Fall
1. What are the positive effects of ash?
It can fertilize plants and is used in tourism to create statues
2. What are the negative effects of ash?
Roofs may cave in, death of animals and plants, pneumonia dn other respiratory diseases from inhaling ash.
3. How can volcanic eruptions affect global weather?
Volcanic eruptions can trigger lightening, thunderstorms and whirlwinds (including tornadoes). The heat can
melt snow and glaciers which can lead to flooding and landslides, can affect weather by blocking the sun and
lowering temperatures.