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Earthquake warning for California fault line proves accurate


California earthquake experts have been saying for weeks that the 7.2 temblor on Easter Sunday in Mexicali had placed pressure on two Southern California fault lines -- the Elisnore and the San Jacinto -- making quakes there more likely.

They proved prescient. 

The 5.4 earthquake that rattled Southern California on Wednesday evening appeared to hit along the San Jacinto fault, officials said. That fault runs roughly from the Salton Sea area northwest through the San Jacinto Mountains toward San Bernardino.

Scientists are now studying how the Mexicali quake changed the pressure of various Southern California fault lines. One questions: Did the temblor make quakes more likely along more dangerous fault lines, such as the Whittier — which produced the deadly 1987 Whittier Narrows quake? Scientists are particularly interested in the Whittier fault because it's connected to the Elsinore and runs under heavily populated areas.

The 5.4 quake on Wednesday wasn't exactly an aftershock of Mexicali.

"We've been calling those 'triggered earthquakes,' " Caltech seismologist Kate Hutton said, referring to temblors north of the aftershock zone that runs from the Gulf of California to Ocotillo, Calif., near the Mexican border.

"We've been able to see an increase in activity," Hutton said. Wednesday's earthquake was the largest to hit the Elsinore and San Jacinto fault zones since the April 4 shaker.

-- Rong-Gong Lin II and Hector Becerra

Map credit: University of Oregon

Comments () | Archives (27)

Yesterday's shaker in Borrego Springs happened at the height of rush hour traffic, catching many motorists in their cars when it hit. But few people know what to do if they are in their cars and an earthquake hits. As we all know, the Northridge Earthquake brought down several freeways, including the Santa Monica Freeway, near my home in Venice. Because Northridge happened so early in the morning, few people were injured on the roads, but a CHP motorcycle officer was killed when he plunged off of a collapsed freeway.

If you are in your car during an earthquake the best thing to do is:
• Try to make your way to the shoulder or right of the road as safely as possible
• Make sure you’re not under an overpass, electrical wires and light poles or tall trees
• Make a visual assessment of the freeway/road conditions before starting out again
• And stay tuned to local broadcasts to find out if roads have been affected.

Pete Moraga
Communications Specialist
Insurance Information Network of California

The prediction of increased stress on Elsinore and San Jacinto faults was rather obvious; it is nowhere close to be an "earthquake warning."

The title of the article is completely misleading.

You know things are going to be bad when Dr Kate starts talking about "increases in activity." Ditto Dr Lucy.

'Scientists are particularly interested in the Whittier fault because it's connected to the Elsinore and runs under heavily populated areas."

The proper action would be to de-populated the areas. Likely the areas will become yet more heavily populated as our "leaders" allow the population of the U.S.A. and California to grow ever larger. And then what?

Just another reason to get yourself prepared for the "big one"

Just a small correction: The policeman killed was a LAPD motor officer heading to work.

That's funny they have been warning us for weeks. This was the first time I heard about it. Funny how these "so called" scientists now predict a quake after a quake.

predicting earthquakes is like predicting the future

The big one is coming the big one is coming!!!

Here are the theories:

Seismic Gap
Drought to heavy rainfall
Hightened activity - swarm effect
Seismic Propagation (Yesterday's EQ)
Magma Movements - under crust weather patterns - sort of like sun spots - whereas cold spots cause changes in sub-crust convection forces.

The best one is the weather connection. This one highlights the fact that tectonic based quakes are rare. Instead, large shallow quakes are caused by massive static discharges from ground to atmosphere causing a bounce in the crust - highlighted by P&S wave gap compression.

Frankly, there are too many forces at work to accurately pinpoint the next break. However, you can ascertain increased hazards over an area based on sudden activity or the lack thereof.

My warning is that we should expect a quake where we don't expect it. In this case, the seismic gap is the coachella segment of SAF. While it might not break there, seismic propagation would point to either side of the SAF in that region. We had Landers and Hector Mine to the east. To the south we had the Easter North Baja event. Nothing to the north unless you claim Northridge as a force shift (so can a Tehachapi event). That leaves west where we have choices: Newport-Inglewood, Elsinor to Whittier gap break, or Northern Elsinor event. I vote of EW since it is a Murphy's law scenario - requiring less energy release to cause equal damage as in the dreaded coachella event (big one.)

Again these are theories. Factor's that will affect these are tidal, thermal and hydraulic in nature. The continued seismicity to the south is a clear indication that things are continually settling under the crust.

So have water, food, emergency equipment on hand at all times. Make sure to have cash in small bills as I expect to be without any kind of decent order for 7-10 days (Remember Katrina). Also expect major events to occur in a Sept-October and January to Mid-March scenario - based on historical statistics. Again these are observations that lead to more theories.

Finally, while a major event would be catastrophic , it also comes with a major silver ligning. In 1994, we were at the end of a significant recession, base closures and Fortune 500 flight from the LA basin. The northridge quake was a catalyst to precipitate us out of our economic stagnation. This would indeed put a lot of people back to work as well as put tons of insurance and government money on the pavement.

My 3 cents

In future all predictions will have become true unless they were from crack pots.

Am I famous yet?

California has been quiet seismically for a long time. It's just waking up is all.

Be ready, you never know when The Big One will hit!

So they have something to write about. Scientists are not God, they think they can predict everything. As they predicted there are going to be a big one, but when and where which they don't know just only guess.

tarwater.....You need to stop drinkin that stuff. It's affecting your ability to think clearly.

"De-populated"? (Or, what I think you meant, "de-populate")

Are you for real with this? Please elaborate. I've gotta hear this!

"That's funny they have been warning us for weeks. This was the first time I heard about it. Funny how these "so called" scientists now predict a quake after a quake."

Bill, if you actually read this article, it has a link to a news report on JULY SECOND talking about the increased pressure on the San Jacinto and Elsinore faults.

So maybe it's the first YOU'VE heard about it, but obviously, if you were following the news, you might have seen the report!

These scientists can't win. They spend decades upon decades studying the earthquakes and faults of SoCal, covering our state with instruments that track every movement and stress, all to help us plan ahead. When they finally start getting enough data to start pinpointing where the stresses are and where a quake is most likely to go off, people either accuse them of playing God for making some tentative predictions, or sneer at them for not knowing more, or ignore their reports until after the fact and then saying, "You didn't tell us!"

"Foolish is the man that bulit his land upon the sand"

"The best one is the weather connection. This one highlights the fact that tectonic based quakes are rare. Instead, large shallow quakes are caused by massive static discharges from ground to atmosphere causing a bounce in the crust - highlighted by P&S wave gap compression."

Bouncy crust? Thats freakin' so riduculous it cames all the way back and is actually pretty funny.

Joe: my advice to you is to get a job, sir!! (Big Lebowski)

"There is going to be earthquakes in Southern California in the future" - that is not news. I completely agree that the article is misleading, since it is hardly a prediction.

I do not think earthquakes would ever be predicted through conventional scientific methods, however, theres is hope. It is well documented that many animals can sense when an earthquake is about to happen, it is a matter of investigating what is it that they are sensing (magnetism, etc). I once read a paper that in Japan, cat fish in tanks have been the best at predicting earthquakes by their erratic behavior well before the happen.

Peter M, had you seen the speech by Dr. Hutton on Easter she stated that this COULD and most likely will cause other Faults to give very soon so I would say she was correct. This is not exact Science but based on previous earthquakes and known activities. I have watched Dr. Hutton and other Caltech seismologist and they are pretty close to what they know. I have prepared items at home and in my cars. I make sure I have food, plenty of water, flashlights, good batteries, I have gas for both my generators, meds, food with long shelf life, first aid, escape plan, dog food, shelter in the back yard, sleeping bags so I am prepared, and you.

Hi Rong-Gong Lin II and Hector Becerra,

Ever hear of spell and grammar check? You have several errors.

we wont have the big one just yet,, just a bunch of 6.something and lower ..

I am 18 and ever since the earthquake from easter I have been completely traumatized.

The day of the easter one I had like a panic attack that could of lead to something worse.

It was bad.

Ever since then everytime I hear anything about earthquakes I feel this insecurity. How bad could the "BIG ONE" be.

Again, I dont really know much about all this stuff but I wish I could get some info.

My boyfriend states, that the oil spill pressure on the ground does contribute to possible ground movement.

No matter what the seismologists say, I am a firm believer in actions speak louder than words. First of all, all the residents of So. Cal, that are living in rundown housing, you had better GTFO. South is a good direction, because the 7.2 is sending pressure North. 3-500 miles beyond the border is probably safe. Now, if you see Kate Hutton, Lucy Jones and Egil Hauckson leaving town, you might be advised to follow them. They really do know something you don't. They have been playing this game for over 30 years and if they are gettin' outta Dodge, there is a mean hombre' a comin'. His name will be Shake'em Hard Slim and he will be wearing 8.5 boots. I'm sure glad I got out of there in 2005.

The only error in the article is the headline, which implies there was a specific prediction/warning. I read the previous July 2 article, which only stated that there was concern about increased risk on the Elsinore and San Jacinto Fault systems. This proved to be the case - the science works and this is the best we can hope for with the current state of understanding. This quake might have been sufficient to reduce accumulated stress along the San Jacinto. But if there is continued activity on the San Jacinto, then it is possible it could migrate north along that system or transfer stress to the adjoining systems, the Elsinore/Whittier or the San Andreas (o0ps).

When I feel it here in Colorado I'll know the ultimate stress reliever has occurred.

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