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Liquefaction – waves liquefy H2O filled sedimentsoGroundwater forces grains apart reducing frictionoLiquefied sediments flow as slurryoSand becomes “quicksand” clay becomes “quickclay”oSand blows and sand volcanoes disrupt ground surfaceLiquefaction-Liquefaction causes soil to lose strength-Land, and the structures on it, will slump and flow-Buildings may founder and topple over intactFires-Fire is frequently realized earthquake hazardoShaking topples stoves, candles, and power linesoBroken gas mains and fuel tanks ignite a conflagrationoInfrastructure (water, sewer, electricity, roads) destroyedoFirefighters are often powerless to combat fireNo road accessToo many hot spotsTsunamis-Tsunamis result from displacement of the sea flooroEarthquakes, submarine landslides, or volcanic explosion-Faulting displaces the entire volume of overlying water oA giant mound (or trough) forms on the sea surfaceoThis 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 waterTsunami Signs-Strong ground shaking from an earthquake: if you are on the coast andthere 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
-Loud ocean roarEarthquake prediction-They can be predicted in the long term-They cannot be predicted in the short term-Hazards can be mapped to assess riskLong term earthquake prediction-Probability of a certain magnitude earthquake occurring -Requires determination of seismic zones and recurrence intervals by:oEvidence of seismicity – fault scarps, sand volcanoesoHistorical recordsoGeologic evidenceEarthquake prediction-Short-term predictions oGoal: the location and magnitude of a large earthquakeoCurrently, no reliable short-range predictions are possible Lecture 10 – Minerals & CrystalsWhat 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 mineralsoThese 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
oVerterbrate bones (apatite)oOyster, mussel or clam shells (aragonite)oOther skeletal typesoOur own tooth enamel (apatite)Solid-A state of matter that can maintain its shape indefinitely-Minerals are solids, not liquids or gases