From: lockhart@mothra.nts.uci.edu (Jack C. Lockhart)
Subject: Re: the coming "big" one
Newsgroups: ca.earthquakes
Organization: University of California, Irvine
Date: 29 Dec 92 06:14:49 GMT
Followup-To: ca.earthquakes

In article <1992Dec28.232226.11317@wvus.org> pete@wvus.org (Pete Gregory) writes:
>Why is the coming "big one", estimated at (what was it?) 8.5, figured to
>cause such widespread damage, when its Richter value is only a little
>higher than the Big Bear and Landers quakes earlier this year?
>Geographically, their distance from metro L.A. is not that different.
>Experts, please enlighten me...
>-- 
>
>Pete Gregory, World Vision U.S.   Internet: pete@wvus.org
>                                  Bangpath: ames!elroy!wvus!pete
>

I am not a expert on the subject.  Just want to pass along a few
tibbits of information.  I am sure that the pro's will correct any
errors.

The following table shows that a magnitude 8.5 earthquake produces 10
times more ground motion that a magnitude 7.5 earthquake, but it
releases about 32 times more energy.  The energy release best
indicates the destructive power of an earthquake.

     Table Reprinted from the Geo-Monitor, December 1992, pg. 19.

           Magnitude vs. Ground Motion and Energy

Magnitude Change     Ground Motion Change         Energy Change

     1.0                10.0 times                about 32.0 times
     0.5                 3.2 times                about  5.5 times
     0.3                 2.0 times                about  3.0 times
     0.1                 1.3 times                about  1.4 times

Table supplied by the National Oceanic and Atmospheric Administration
(NOAA).

Personally, the 45 seconds of shaking associated with the 7.5 Landers
earthquake was 44.9 seconds too long for my taste.  I can't imagine
and don't want to experience 10.0 times more ground shaking associated
with an 8.5 quake.  No thank you - please.

~jack_

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