Posted on 06/21/2006 10:33:10 AM PDT by 300magnum
The southern end of the San Andreas fault near Los Angeles, which has been still for more than two centuries, is under immense stress and could produce a massive earthquake at any moment, a scientist said on Wednesday.
Yuri Fialko, of the Scripps Institution of Oceanography at La Jolla, California, said that given average annual movement rates in other areas of the fault, there could be enough pent-up energy in the southern end to trigger a cataclysmic jolt of up to 10 metres (32 ft).
"The observed strain rates confirm that the southern section of the San Andreas fault may be approaching the end of the interseismic phase of the earthquake cycle," he wrote in the science journal Nature.
A sudden lateral movement of 7 to 10 metres would be among the largest ever recorded.
According to the U.S. Geological Survey (USGS), the earthquake that destroyed San Francisco in 1906 was produced by a sudden movement of the northern end of the fault of up to 21 ft.
Fialko said there had been no recorded movement at the southern end of the fault -- the 800-mile long geological meeting point of the Pacific and the North American tectonic plates -- since the dawn of European settlement in the area.
He said this lack of movement for 250 years correlated with the predicted gaps between major earthquakes at the southern end of the fault of between 200 and 300 years.
Elsewhere on the fault, there were average slippage rates up to a couple of centimeters a year that prevented the build-up of explosive pressure deep underground.
When these became blocked and then suddenly broke free they produced tremors or earthquakes of varying intensity depending on the movement that had taken place before and the duration of the blockage.
USGS says the most recent major earthquakes in the northern and central zones of the San Andreas fault were in 1857 and 1906.
Fialko said there were three possible explanations for the lack of observed movement in the southern section -- creepage under the surface that had no external manifestation, that it simply might not move as much as the rest or a major blockage.
"Except for the first possibility above, the continued quiescence increases the likelihood of a future event," he wrote.
Making calculations based on a wide range of land and satellite observations, he discounted the idea of creepage and warned of impending disaster.
"Regardless of fault geometry and mechanical properties of the ambient crust, results presented in this study lend support to intermediate-term forecasts of a high probability of major earthquakes on the southern SAF system," Fialko said.
Yikes!
What's being done? It's obvious that President Bush just doesn't care about Mexican people.
Has Al Gore been consulted on this?
Back in 1989, the Loma Prieta Earchquake caused the San Andreas to move some 30 feet on the Southern end, and only 6 feet on the Northern end. That energy has to go somewhere, some time. It will be like a slingshot.
No thread highjacking!
Yes, but this is San Andreas Fault, not Bush's Fault.
This article writes itself every few years
Too damn many illegals putting on too much weight to the fault line!...........(Thread hi-jacking in progress)..........
Don't ya know, it's ALL BUSH'S fault!
Maybe they'll rename it the Bush Fault.
Only God is in control of this.
Ooops, the left hates Him too!
Why isn't FEMA there already?
I CAN'T WAIT!
Double YIKES, Hope Free Republic is safe, now that I'm addicted.
move. now.
Squawkin' 7500...
http://earthquake.usgs.gov/eqcenter/recenteqsus/
I go to the USGS site every morning. California shakes like a bowl of freakin' jello as well as Alaska.
Gotta love that Rove. 9-11, Katrina, now this!
That guy must never sleep.
???.......
I've lives in California all my life, and I've been hearing this since I was about 5. How is this news? "The Big One" is about as much a part of California lore as the 49er legends.
OTOH, developers are having a field day in the desert nowadays. 30 years ago a big quake out there would have shaken the hell out of the Marine base and damaged the resort cities, but the major population centers were far enough away that serious damage would have been minimal. Nowadays we have developers building practically right on top of the fault, and the cities in the desert are getting HUGE...LA has sprawled all the way out there.
A big quake would be very, very bad for them, but that's the price of living in California :)
So...what about San Diego? Just tremors, right? :o) *fingers crossed*
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