GEOL 1121 Lecture Notes - Lecture 5: Richter Magnitude Scale, Water Column, Surface Wave
17 Mar 2018
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Document Summary
Earthquakes caused by sudden earth movements of up to several meters. Energy released propagates away as seismic waves (earthquake waves spread just like the waves on a pond when you throw a rock) Surface waves direct comparable to the most damaging earthquake waves. We use seismic waves like x-rays to see the structure of the earth. Ground shaking can be amplified in loosely consolidated sediments or fill. Triggers liquefaction of soils (water saturated soils behave like liquids) Ground - shaking and nature of bedrocks and soils. State of infrastructure (i. e. gas and water lines were ruptured) Ground shaking triggers landslides beneath the ocean the cause of tsunamis. Tsunami trigger: displacement of seafloor (can be due to landslides as well as earthquakes) Typical open ocean waves in a gale: Wavelength 450 m, amplitude 10 m, velocity 100 km/hr. Wavelength 100 km or more, amplitude 1 m, velocity 1000 km/hr.
