Term
| What causes an earthquake? |
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Definition
| Earthquakes are caused by the vibrations of Earth produced by the sudden release of energy. |
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Term
| Describe the location of an epicenter and focus. |
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Definition
Epicenter - location on the surface of Earth directly above the focus
Focus - the point within Earth where the earthquake starts |
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Term
| What is the elastic rebound hypothesis? How does it relate to earthquakes? |
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Definition
| Elastic rebound hypothesis is the release of built-up energy. Most earthquakes are produced by the release of elastic energy stored in rocks that has been subjected to great forces. |
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Term
| Describe aftershocks and foreshocks. |
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Definition
Aftershocks - small quakes that come after a major earthquake
Foreshocks - small quakes that occur before a major earthquake |
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Term
| How are earthquakes measured? |
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Definition
| Historically, scientists have used two different types of measurements to describe the size of an earthquake - intensity and magnitude |
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Term
| Describe the following earthquake waves: surface, S waves, and P waves |
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Definition
Surface waves - seismic waves that travel along Earth's outer layers. They move up, down, and side to side. Most destructive earthquake wave. Last to arrive at the seismograph.
S waves - shake particles at right angles to their direction of travel. Also known as traverse waves. Can only travel through solids. Slower than P waves but faster than surface waves
P waves - They push (compress) and pill (expand) rocks in the direction the wave travels. Also known as compression waves. Can travel through solids, liquids & gas. Fastest wave (arrive 1st to the seismograph)
the order should be P,S,Surface |
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Term
| How do scientist locate earthquakes? (distance and direction) |
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Definition
| The difference in velocities of P waves provides a way to locate the epicenter. Scientists use a travel-time graph, in which one needs at least 3 seismograph station data. |
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Term
| Where do most earthquakes occur? |
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Definition
| Most of these earthquakes occur around the outer edge of the Pacific ocean. This zone is known as the circum-Pacific belt. Active earthquake in this zone include Japan, the Phillipines, Chile, and Alaska's Aeulation Islands |
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Term
| Describe each of the different scales used to measure earthquakes. Which one measures intensity and which one measures magnitude? What is the difference between magnitude and intensity? |
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Definition
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