EPS C20 Lecture Notes - Lecture 15: Alluvium, Body Wave Magnitude, Andrew Lawson
17 Nov 2020
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Intensity and magnitude: you need to know the difference. These are about the impact of the quake. Scientists need to measure the solid earth processes: Intensity : people"s descriptions of what they felt. Magnitude : instrumental measurements with seismometers that account for the distance to the quake source. A measure of the energy of the quake. Not dependent of location -- one value per quake. 1906 earthquake: the lawson report -- andrew lawson. Maps of the fault location & ground shaking distribution. Intensity - modified mercalli intensity (mmi) scale. Pink - recent marine sands & alluvium . The closest distance of the site to the fault rupture. Ground condition at the site: rock vs soil vs landfill. Today we use shakemap to map ground shaking. Peak ground shaking (pgv) > (mmi) modified mercalli intensity. Map available from us geological survey national earthquake. Seismic data provided by uc berkeley & caltech us geological.
