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Re: 7.0 Landers Aftershock

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     It is my understanding that an aftershock is like the waves in a
non-uniform container when you drop a pebble  into it.  They are all
BASICALLY disipating but sometimes add harmonically to produce a wave that
is more than the response amplitude but less than the first perturbation.
These with normal damping would probably disipate within a day or so.  This
seems to be the norm as the nature of EQ's as I percieve it.

-----Original Message-----
From: Charley Hamilton <chamilto(--nospam--at)>
To: seaint(--nospam--at) <seaint(--nospam--at)>
Date: Monday, October 18, 1999 4:37 PM
Subject: Re: 7.0 Landers Aftershock

>I'm somewhat outside my area of expertise, but I was given to
>understand that an aftershock is when new motion occurs on the
>rupture surface generated by an earlier earthquake.  That is, if an
>earthquake broke line AF from C to D, and a new quake occurred along
>CD, that would be an aftershock.  I assume.  The problem is I'm
>not clear on a "time limit" for said aftershock, or a magnitude limit.
>(Can a 6.0 have a 7.5 aftershock?  Logically no, but hey, this is
>Science...)  Also, it is likely that aftershocks will cluster near the
>ends of the rupture surface (I *think* what the guys at that OES meeting
>were trying to say).
>I'll take a look around & see if my seismology text [blows dust off]
>has anything useful to say on the matter.
>More later.
>Charles Hamilton, EIT                   Graduate Student Researcher
>Department of Civil and                 Phone: 949.824.8694
>    Environmental Engineering           FAX:   949.824.2117
>University of California, Irvine        Email: chamilto(--nospam--at)