Geo101.12.Earthquakes[1]

Geo101.12.Earthquakes[1] - Earthquakes San Francisco Bay...

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1 Earthquakes San Francisco Bay Earthquakes in the News … Earthquakes happen when the Earth’s crust frst bends, then suddenly snaps and breaks… This breaking generates vibrations or seismic waves Radius = 6370 kilometers = 4000 miles 1) sudden ±ormation o± new ±ault or ±racture 2) sudden slip on an existing ±ault 3) sudden rearrangement o± minerals in a rock 4) volcanic eruptions 5) landslides 6) meteorite impacts 7) underground (human-made) explosions Seismicity (Earthquake activity) can occur ±or several reasons …the place on Earth where rock ruptures and slips or the place where an explosion occurs is the ±ocus (or hypocenter ) o± the earthquake …the point on the sur±ace o± the Earth that lies directly above the ±ocus is the epicenter
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2 Where and why do earthquakes occur… 3 major classes of Earthquakes. . 1) Shallow focus (top 20km of the Earth) …these are the most damaging 2) Intermediate focus (20 and 300 km) 3) Deep focus (300 to about 670 km) Earthquakes at Plate Boundaries Continental transform boundaries Continental rifts and collisions Intraplate earthquakes Shallow focus < 10 km Earthquakes at Plate Boundaries Convergent boundaries shallow, intermediate and deep focus The inclined zone of seismic activity produced by the interaction of the downgoing, subducting, oceanic plate beneath an overriding continental or oceanic plate. This band of seismic
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Geo101.12.Earthquakes[1] - Earthquakes San Francisco Bay...

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