Liquefaction waves liquefy H 2 O filled sediments o Groundwater forces grains

Liquefaction waves liquefy h 2 o filled sediments o

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Liquefaction – waves liquefy H 2 O filled sediments o Groundwater forces grains apart reducing friction o Liquefied sediments flow as slurry o Sand becomes “quicksand” clay becomes “quickclay” o Sand blows and sand volcanoes disrupt ground surface Liquefaction - Liquefaction causes soil to lose strength - Land, and the structures on it, will slump and flow - Buildings may founder and topple over intact Fires - Fire is frequently realized earthquake hazard o Shaking topples stoves, candles, and power lines o Broken gas mains and fuel tanks ignite a conflagration o Infrastructure (water, sewer, electricity, roads) destroyed o Firefighters are often powerless to combat fire No road access Too many hot spots Tsunamis - Tsunamis result from displacement of the sea floor o Earthquakes, submarine landslides, or volcanic explosion - Faulting displaces the entire volume of overlying water o A giant mound (or trough) forms on the sea surface o This feature may be enormous (up to ten thousand square mile area) - When the sea floor moves, it pushes water forward - They are often imperceptible because of low wave amplitude (height) and long wavelength - When the water gets shallower, it slows down the bottom of the wave and forces the wave to get taller - They can become monster walls of water Tsunami Signs - Strong ground shaking from an earthquake: if you are on the coast and there is an earthquake, it may have caused a tsunami - Unusual sea-level fluctuations: a noticeable rapid rise or fall in coastal waters - Abnormally huge wave
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- Loud ocean roar Earthquake prediction - They can be predicted in the long term - They cannot be predicted in the short term - Hazards can be mapped to assess risk Long term earthquake prediction - Probability of a certain magnitude earthquake occurring - Requires determination of seismic zones and recurrence intervals by: o Evidence of seismicity – fault scarps, sand volcanoes o Historical records o Geologic evidence Earthquake prediction - Short-term predictions o Goal: the location and magnitude of a large earthquake o Currently, no reliable short-range predictions are possible Lecture 10 – Minerals & Crystals What is a mineral? A naturally occurring solid, formed by geologic processes, that has a crystalline structure and definite chemical composition. - Naturally occurring - Formed geologically - Solid - Crystalline structure - Definite chemical composition - Inorganic (with a few exceptions) Naturally occurring: - A true mineral is created naturally - Humans can recreate natural processes to make minerals o These are synthetic materials. Geologic Process - Freezing from a melt - Precipitation from a dissolved state in water - Chemical reactions at high pressure or temperatures Living organisms can create minerals - Called biogenic minerals to emphasize its origin
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o Verterbrate bones (apatite) o Oyster, mussel or clam shells (aragonite) o Other skeletal types o Our own tooth enamel (apatite) Solid - A state of matter that can maintain its shape indefinitely - Minerals are solids, not liquids or gases
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