FNR 10300 Lecture Notes - Lecture 30: Seismic Wave, Geologic Hazards, Hypocenter
7 Nov 2016
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Document Summary
Sudden release of energy stored in rocks: applied stress exceeds strength of rock. Any fracture in the earth, of any size, that shows offset. A fracture that has simply opened up is a joint. If that fracture shows some type of sideways slippage, then it becomes a fault. Epicenter is the point on the surface that is directly above the hypocenter. Seismic stations- wave arrives at closer seismic stations first. Stress drops during quake, followed by post-slip recovery of elastic strain; cycle starts again. Each increase in magnitude- 10 times more shaking, but about 32 times more energy. Big earthquake, far away means a little shaking. One earthquake (single magnitude) can yield variable intensities. Different ground surface types: soft, hard, well packed, not well consolidated, water-saturated, etc. Rupture: along parts of the faults, can destroy buildings and roads. Tsunami: cause damage along shorelines and thousands of kilometers away.
