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Re: 7.0 Landers Aftershock

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A question for the list.

The Landers earthquake happened several years ago.  If I remember correctly
the Magnitude was also around 7.0.  At what point does a new earthquake
cease to be an "aftershock" ?

Paul Feather

----- Original Message -----
From: <Seaintonln(--nospam--at)aol.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Saturday, October 16, 1999 3:51 AM
Subject: 7.0 Landers Aftershock


> The news is reporting a series of earthquakes begining with a 6.6
aftershock
> of the Landers quake begining around 2:46AM this morning. Almost
immediately
> after, the high desert and the Coachella valley (low desert) in the 760
area
> code, was hit with a 7.0 after shock. Within the next hour there was a
number
> of after shocks around between 2.4 and 4.5 in magnitude.
>
> The epicenter has been reported by Cal Tech as 32 miles north of Joshua
Tree
> and Yucca Valley. Joshua Tree area is not highly populated, however, there
is
> a concentration in the towns of Yucca Valley.
>
> The quake lasted a little over 30 seconds and was a strong rolling quake.
> Those who are calling in from the area (Palm Springs, Palm Desert, La
Quinta)
> have reported no structural type damage - although it is still very early
to
> tell, but I would not expect much. There is no power outages reported -
> although I have not checked the scanners.
>
> If there is damage in the town of Joshua Tree or Yucca Valley that
requires
> the help of local engineers to assess damage, I would suggest that anyone
who
> has contacts with the emergency response teams relay the message to the
list
> and provide a contact for us to call.
>
> I will keep the list updated as reports come in. This is not very friendly
to
> occur when some of us insomniac's just fall asleep:o)
>
> Dennis S. Wish PE
>