earthquakes 16.2

earthquakes 16.2 - Earthquakes 16.2 11.6.07 I. Magnitudes...

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Earthquakes 16.2 11.6.07 I. Magnitudes a. Local magnitude i. = richter magnitude 1. based on 1 second shear waves 2. amplitude on seismograph is 10X bigger for every earthquake a. amplitude of ground motions is 10x fro every magnitude unit. b. Moment magnitude (Mw) i. Measures energy release of earthquake 1. measures whole spectrum of frequency content a. seismic moment goes up by factors of 32 i. every .2 magnitude units = doubled moment 2. makes seismic moment number user-friendly II. Directivity of source (why damage occurs where it does) a. San Francisco 1906 i. Ruptured both sides—directivity pulse in both directions (unzipping of fault) 1. see Fig A; when rupture and fault slip is in one direction = directivity b. 1994 northridge i. Looking down on fault plane 1. see Fig. B c. 1999 Taiwan earthquake i. Not as much damage as expected; due to fact that there was not much source directivity 1. see fig C 2. see fig D ii. rupture propagation was perpendicular to the fault slip 1. thus damage was not that severe
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This note was uploaded on 01/23/2009 for the course GEOL 240Lxg taught by Professor 12:30-01:50pm during the Fall '07 term at USC.

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earthquakes 16.2 - Earthquakes 16.2 11.6.07 I. Magnitudes...

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