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Earthquakes

1959 earthquake at Hebgen Lake, MT. 1995 landslide in La Conchita, CA. EARTHQUAKES ... PRINCIPAL EARTHQUAKE ZONES. Intraplate Earthquakes ...

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Earthquakes

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  1. POSER? If you place an ice cube in a glass of water and mark the water level, when the ice has fully melted, will the water level by higher, lower or the same?

  2. EARTHQUAKES EFFECTS OF EARTHQUAKES LANDSLIDES AND LIQUEFACTION Shaking and tremors dislodge unstable masses of rocks and soil on hillsides. Fragments can be dislodged from bedrock and buildings as well.

  3. EARTHQUAKES EFFECTS OF EARTHQUAKES LANDSLIDES 1959 earthquake at Hebgen Lake, MT 1995 landslide in La Conchita, CA

  4. EARTHQUAKES EFFECTS OF EARTHQUAKES FALLING DEBRIS

  5. EARTHQUAKES EFFECTS OF EARTHQUAKES LIQUEFACTION Conversion of unconsolidated material with some initial cohesiveness in to a mass of water-saturated sediment that flows like a liquid, although no water has been added. Shaking increases the pressure on the water between the sediment grains, forcing them apart Loss of frictional contact produces a slurry of sediment and mud

  6. EARTHQUAKES EFFECTS OF EARTHQUAKES LIQUEFACTION Turnagain Heights, AK 1964 Government Hill Elementary School Anchorage, AK, 1964

  7. EARTHQUAKES EFFECTS OF EARTHQUAKES LIQUEFACTION Kobe, Japan

  8. EARTHQUAKES EFFECTS OF EARTHQUAKES LIQUEFACTION Kobe, Japan

  9. EARTHQUAKES EFFECTS OF EARTHQUAKES LIQUEFACTION Port Royal, Jamaica 1692 City slid 15 m below sea level.

  10. EARTHQUAKES EFFECTS OF EARTHQUAKES SEICHES (pronounced sayshes) Seismic waves cause water in an enclosed basin to oscillate. Can occur miles from the focus or epicenter of the earthquake.

  11. EARTHQUAKES EFFECTS OF EARTHQUAKES TSUNAMI Translated from Japanese means “harbor wave”. Not a “tidal wave”. TSUNAMI is a very long wavelength, high-speed ocean wave, produced by earthquakes. Wavelength can be up to 160 km. Velocities reach 800 km/hr (500 mph). Generally imperceptible at sea, crest only 1 m high. Water bunches up when the wave “feels bottom”. Wave height can reach 65 m (210’).

  12. EARTHQUAKES EFFECTS OF EARTHQUAKES TSUNAMI Produced by large, rapid displacement of sea floor due to submarine faulting. Can also be produced by submarine landslides. Tsunami hitting Hawaii following an earthquake in Alaska in 1946

  13. EARTHQUAKES EFFECTS OF EARTHQUAKES TSUNAMI 1964 Anchorage Earthquake

  14. EARTHQUAKES EFFECTS OF EARTHQUAKES FIRE Fire is not directly a result of earthquakes, but fire certainly accompanies earthquakes in industrialized setting. Earthquakes rupture gas mains, oil tanks and power lines. They also break water mains which makes fire fighting difficult.

  15. EARTHQUAKES EFFECTS OF EARTHQUAKES FIRE 1906 San Francisco Earthquake

  16. EARTHQUAKES EFFECTS OF EARTHQUAKES Anchorage, AK FIRE Kobe, Japan

  17. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES

  18. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Most earthquakes happen at plate boundaries. Divergent Boundaries Have shallow focus and low magnitude.

  19. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Transform Boundaries Have shallow focus and high magnitude.

  20. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Convergent Boundaries Have deep focus and high magnitude. Deeper focus due to subduction (depths up to 700 km).

  21. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Benioff-Wadati Zone

  22. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Benioff-Wadati Zone

  23. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Benioff-Wadati Zone

  24. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Intraplate Earthquakes Generally have shallow focus and low magnitude. Lower strain due to location away from plate margins. However…... Intraplate rocks are older and colder and more brittle. Less fractured at mid-continent. Thus they transmit seismic waves more efficiently.

  25. EARTHQUAKES Date-Time 2002 04 20 6:50:44.7 Location: 44.507N 73.664W Depth: 5 kilometers Magnitude: 5.1 Region: near Ausable Forks, NY

  26. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Intraplate Earthquakes New Madrid, MO Largest recorded earthquake in North America. Occurred in 1811, lasted 53 DAYS! Three main quakes had magnitudes of ~8.5! 1500 aftershocks. Moved position of Mississippi River Rang church bells in BOSTON!

  27. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Intraplate Earthquakes New Madrid, MO

  28. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Intraplate Earthquakes New Madrid, MO

  29. EARTHQUAKES PRINCIPAL EARTHQUAKE ZONES Intraplate Earthquakes New Madrid, MO (1811) vs. San Francisco, CA (1906)

  30. EARTHQUAKES OTHER EARTHQUAKE FEATURES SEISMIC GAP Parts of faults “stick”. Friction prevents movement in that part of the fault. Force is applies, rocks are stressed. When friction is overcome, fault movement occurs. Areas where major earthquakes could occur.

  31. EARTHQUAKES SEISMIC GAP

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