GS1004 Spotila21 September, 2016Lecture 10: Consequences of Tectonics: Earthquakes IIRelevant reading: Chp. 8, p. 244-279.Motivating questions:Can earthquakes be predicted?What controls the hazards of earthquakes?What does earthquake damage depend on?Damage (and thus hazard) depends on (#1):the distance from the earthquake.Amplitude of waves decreases exponentially with distance.A M6 directly underfoot is worse than a M7 100 km away. Damage is highestwithin a few km of fault.Shaking is most intense within ~10 km of fault.Damage also depends on (#2):the local response of the ground to shaking.Loose, wet sediment (basins) amplifies surface waves; bedrock is safer.e.g. Anchorage, AK 1964, M9.3Liquefaction- water saturated sediment loses its strength when shaken, causingload above to shift and sink.Damage depends on (#3):building construction,In several ways:a)Material, style of buildingb)Technology, engineering, code
GS1004 Spotila21 September, 2016c)adherence to code (economy)
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San Andreas Fault,M6 directly underfoot,metal skeletal structures,poor building construction,good building codes