joking; the Howard Hughes heirs own it--waiting for the Big One so as to own
all that new seafront property.)
----- Original Message -----
From: "Kylie Mckee" <kyliemckee73@yahoo.com>
To: <californiadisasters@yahoogroups.com>
Cc: <kyliejohanson@yahoo.com>
Sent: Sunday, October 10, 2010 5:03 PM
Subject: Re: [californiadisasters] San Andreas fault capable of magnitude
8.1 earthquake over 340-mile swath of California
OH MAN!!! I MUST GET OVER THERE NOW!!!
________________________________
From: Lin Kerns <linkerns@gmail.com>
To: CaliforniaDisasters <californiadisasters@yahoogroups.com>; Geology2
<geology2@yahoogroups.com>
Sent: Sat, October 9, 2010 9:37:52 AM
Subject: [californiadisasters] San Andreas fault capable of magnitude 8.1
earthquake over 340-mile swath of California
San Andreas fault capable of magnitude 8.1 earthquake over 340-mile swath of
California, researchers say
October 8, 2010 | 6:51 am
The "Big One" on the San Andreas fault just got a little bigger.
New research showing a section of the fault is long overdue for a major
earthquake has some scientists saying that the fault is now capable of a
magnitude 8.1 earthquake that could run 340 miles from Monterey County to
the
Salton Sea.
Whether such a quake would happen in our lifetime had been a subject of hot
debate among scientists. That's because experts had believed that a major
section of the southern San Andreas, which runs through the Carrizo Plain
100
miles northwest of Los Angeles, would remain dormant for at least another
century.
But that rosy hypothesis seemed to be shattered by a recent report in the
journal Geology, which said that even that section of the San Andreas is far
overdue for the "Big One." Now, according to U.S. Geological Survey
seismologist
Lucy Jones, it is entirely possible that all 340 miles of the southern San
Andreas could be ready to erupt at any time. Such a scenario would trigger a
magnitude 8.1 earthquake, said Thomas Jordan, director of the Southern
California Earthquake Center, a calculation with which Jones agreed.
"All of it has plenty enough stress for it to be ready to go," Jones said.
"The
biggest implication of [the report] is that it increases the likelihood that
when we do have a big earthquake, it will grow into the 'wall-to-wall'
rupture."
The walls Jones is referring to are the boundaries of the southern San
Andreas,
which begins in the Salton Sea and ends in the town of Parkfield in Monterey
County. Scientists consider the southern San Andreas fault as one segment
generally because it behaves the same -- it rarely rumbles, but when
awakened,
the shaking can be devastating.
In contrast, the section of the San Andreas north of Parkfield up to
Hollister
in San Benito County behaves differently. That section constantly moves at a
creep -- meaning stress is relieved regularly, so large quakes don't occur
there.
Large quakes haven't occurred anywhere on the southern San Andreas for more
than
a century, making it a sleeping giant that has been building stress for so
long
it could snap at any moment.
"My concern is that we will get a series of large earthquakes along the San
Andreas fault," Jordan said. The last "Big One" to rip through Southern
California occurred in 1857, when an estimated magnitude-7.9-quake, ruptured
200
miles of fault between Monterey and San Bernardino counties. It wasn't a
wall-to-wall quake: It stopped near the Cajon Pass, near the present-day 15
Freeway, probably because the fault south of it shook just a few decades
earlier, in 1812, Jones said. Because the 1812 quake had relieved tectonic
tension in that area, it effectively put a brake to the 1857 quake from
moving
further south.
But with the San Bernardino County section of the fault now having
accumulated
two centuries' worth of strain, there may not be any brakes now. "Can I
imagine
the 1857 earthquake happening again and stopping at the Cajon Pass? Probably
not," Jones said. "Once you have a big slip, you're more likely to move
along
down the fault," Jones said. "If the rupture has been made ... that's a lot
of
momentum that will keep the rupture moving down the fault."
The San Andreas has long been considered one of the most dangerous faults in
Southern California because of its length. Not only do longer faults produce
bigger quakes, they emit a type of shaking energy that can travel longer
distances.
"So a much larger area is affected by a really large earthquake," Jones
said.
In 2008, seismologists developed a scenario for a large earthquake on the
San
Andreas -- a magnitude 7.8 shaker that begins at the Salton Sea and barrels
northwest along the fault toward San Bernardino and Los Angeles counties.
-- Rong-Gong Lin II
Photo: Quake researchers study a portion of the San Andreas fault. Ricardo
DeAratanha / Los Angeles Times; Map: U.S. Geological SurveySource
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