Geology Chapter 11 MG – Flashcards
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When a fault is expressed at the surface, it is called a _____.
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fault scarp
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The name of the site where slippage begins and earthquake waves radiate outward is called the _____.
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hypocenter
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If the stress applied to the rock is greater than rock strength, what happens?
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Block sof rock will slide relative to one another along a fault, causing an earthquake.
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The hanging wall moves _____ relative to the footwall in a _____ fault.
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down; normal
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Which of the following might be seen where strike-slip movement has occurred?
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offset fences
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Which of the following is a characteristic of an S wave?
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"shaking" particle motion at right angles to the direction of wave travel
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What best describes the movement of P waves?
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compression and expansion
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Amongst all seismic waves, surface waves _____.
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have the slowest velocity
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The names of primary and secondary refer to _____.
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wave speed
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Define earthquake intensity.
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A qualitative measure of the amount of ground shaking at a certain location
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A smaller earthquake in Virginia was felt over a larger distance, as compared to a larger earthquake in California. What is the reason this occurred?
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colder crust
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Richter magnitude (ML) is derived from measuring _____ and _____, and then plotting them on a Richter diagram.
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S minus P wave time; maximum S wave height
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Why is moment magnitude (MW) preferred over Richter magnitude (ML)?
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Moment magnitude measures the total energy released during an earthquake and can adequately measure the energy of large earthquakes.
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Which of the following best describes liquefaction?
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The transformation of stable soil into loose, liquefied material that is able to rise toward Earth's surface
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Describe how sand volcanoes form.
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An earthquake causes loose, saturated sandy material to liquefy, shoot upward through fractures of a confining unit, and eventually erupt at the surface.
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_____ in the sandy layer causes the ground to subside after sand volcanoes form
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Tighter packing
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Structures build on _____ will become unstable during an earthquake.
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loose, saturated sediments
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A tsunami is caused by _____.
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anything that displaces water
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A _____ is located at a plate boundary between a subducting slab of oceanic crust and an overlying plate.
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megathrust fault
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What happens to tsunami waves as they move closer to shore?
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Velocity decreases and height increases.
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Which of the following locations on the Circum-Pacific Belt are likely to generate a tsunami?
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west coast of South America
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_____ is a seismic zone that has not produced a large earthquake for a considerable length of time.
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A seismic gap
