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Earthquakes & Plate Tectonics
Earthquake: stored energy is suddenly released through a movement along a fault. Fault: is a crack in the Earth’s crust, normally associated with, or form the boundaries between Earth’s tectonic plates.
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Review Types of Faults…
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How do we detect earthquakes?
Seismographs are machines that record seismic waves Seismic waves: vibrations that travel through the Earth caused by earthquakes.
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What are the types of Seismic Waves?
P waves S waves Surface waves
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What are the types of Seismic Waves?
P waves: P stands for primary These waves arrive first Move with a push-pull motion
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What are the types of Seismic Waves?
S waves: S stands for secondary These waves arrive second Move with a side-to-side motion
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What are the types of Seismic Waves?
Surface waves – slowest Cause the most damage Move with an up and down and side-to-side motion
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What are the types of Seismic Waves?
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Epicenter versus Focus
Epicenter: a point on Earth’s surface that is directly above the focus of an earthquake. Where shaking is strongest most damage Focus: point where the earthquake starts. Where rock breaks along a fault and energy is released.
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How do you locate an epicenter?
You need at least 3 seismic stations to locate an epicenter. Where all three circles meet is the location of the epicenter.
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How do you locate an epicenter?
P and S wave can help determine where the epicenter is located. The farther you are the epicenter, the greater the S-P interval (time between when P wave hits and S wave hits)
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How do we determine the size of an Earthquake?
Magnitude: Quantitative measurement of the size of an earthquake from its source. The Richter scale is used to determine magnitude of an earthquake.
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What is a Tsunami? Tsunami: Destructive surge of water that is caused by an underwater earthquake.
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Where do tsunamis occur?
80% occur within the Pacific Ocean’s “Ring of Fire” Active area where volcanoes & earthquake are common
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