California earthquakes felt over a wide area, USGS says

[dipsydoodle]

Source: LA Times

A swarm of moderate earthquakes — including a 5.4-magnitude temblor — was felt across a wide area, according to the U.S. Geological Survey.

The USGS's "Do You Feel It" system shows the quakes were felt as far away as San Diego, Temecula and San Clemente. The 5.4 quake was also felt in Moreno Valley, Indio, National City and Palm Desert. The quakes were centered in and around Brawley on the California-Mexico border.

Read more: http://latimesblogs.latimes.com/lanow/2012/08/swarm-of-moderate-earthquakes-felt-across-border-region-usgs-says.html

[bananas]

1. Series of quakes rock San Diego region

http://www.utsandiego.com/news/2012/aug/26/series-quakes-rock-region/

Series of quakes rock San Diego region

A series of three sizable earthquakes erupted early Sunday afternoon on the San Andreas fault, south of the Salton Sea, causing shaking that was felt across the region from San Diego and Imperial counties to northern Orange County.

The first quake was a 5.3 that occurred four miles southeast of Westmorland at 12:30 p.m, according to the U.S. Geological Survey.

That was followed one minute later by a 5.4 quake in the same area. Then there was another 5.3 at 12:32 p.m. a short distance away, the USGS said.

<snip>

Three quakes of that size close in time is unusual, but it does not necessarily mean a larger event is imminent, earthquake experts.

<snip>

The quake caused a lot of shaking in the heavily congested stands at the Del Mar race track and people did look around but there was no panic.

<snip>

[AnotherMcIntosh]

3. Some seem to think that building a nuclear power station at San Onofre may have been a mistake.

Maybe it is so safe that no quakes could affect it.

[bananas]

2. Cluster of quakes rattle Brawley, south end of Salton Sea

http://www.mydesert.com/viewart/20120826/NEWS0805/120826002/Cluster-quakes-rattle-Brawley-south-end-Salton-Sea

Cluster of quakes rattle Brawley, south end of Salton Sea
1:04 PM, Aug 26, 2012

<snip>

Preliminary USGS reports indicated that three quakes larger than magnitude 5.3 rattled outward from an area 3 miles north of Brawley, a small farming town in the Imperial Valley.

The largest three quakes struck in the two minutes starting at 12:30 p.m.

<snip>

The episode began when Brawley was reportedly rocked by a magnitude 3.9 quake at 10:02 a.m., followed by a 3.4 quake about 90 seconds later.

In the three hours after the first earthquakes, an additional 11 quakes struck the same approximate epicenter near the Salton Sea.

<snip>

[xchrom]

4. Du rec. Nt

[bananas]

5. Just felt another one. nt

[AnotherMother4Peace]

6. A second 5.4 just now.

[Scairp]

7. This isn't very good

When you have a small event followed by larger ones that isn't a good thing. It's the main event followed by smaller aftershocks you want to see not the other way 'round. Not saying it is, but there is always the possibility that these are forequakes, which would suck for us up here in S.B. county because if it's very much bigger than 5.4 we will be affected. Is everyone stocked up on their bottled water, canned food and propane in the event you lose power for a few days?

[TalkingDog]

9. Yep, that's the sense that I get. More like Fukushima than the last big CA quake

which was a big quake and some after shocks.

[AntiFascist]

10. There was a series of foreshocks the night before the Northridge quake...

in Santa Monica. I distinctly remember the newscaster saying "this does not necessarilly mean it will be followed by a large quake."

[TalkingDog]

8. Holy Cow! Quake map of the area.

Look at that page full of quake reports!

http://quakes.globalincidentmap.com/

[Scairp]

11. This is totally normal for CA

We have earthquakes every single day here. I still haven't felt a thing today. So many factors are at play in determining who is affected by a quake. What bothers me is, as I said, a small event followed by a larger one.

[greyl]

12. Not quite. nt

[slackmaster]

25. It's normal for an area that has long been known to scientists as the "Brawley Seismic Zone"

Seismologist Lucy Jones of the USGS said the activity was not uncommon for the area, a region known as the "Brawley Seismic Zone" that sits between the San Andreas and Imperial faults. Similar swarms occurred in the area in the 1970s, she said, the most recent in 1981....

http://latimesblogs.latimes.com/lanow/2012/08/earthquake-swarm-classic-activity-for-brawley-area-usgs-says.html

[heaven05]

18. thanks

great link to add to noaa, usgs, ect

[Fermentia]

13. I felt the one around 2:00

here in Los Angeles. It was about 2 minutes of gentle swaying.
I get email updates from the USGS site whenever there is an earthquake larger than 3.0 in my area. So far today I have received 75 emails.

[XemaSab]

22. Welcome to DU!

And lulz at the 75 emails.

[Viva_La_Revolution]

14. most activity since the 70's, expected to continue for a few days, live quakecam link

Watch a live news stream of the quake cam in the KABC-TV newsroom, covering Los Angeles and Southern California.
http://abclocal.go.com/kabc/livenow?id=7367462

snip>
"Our system is choking on so many earthquakes," Jones said. "This area of California is deep soils, and we do not get as precise data as we do over the rest of the state, and that makes our data a little less precise."

Jones said the quake swarm was about midway between fault complex on the west side of the Imperial Valley, and the main branch of the San Andreas Fault, which runs from near Palm Springs to enter Mexico just west of Yuma.

"These don't seem to be related to earthquakes on the San Andreas itself, other than in a general way," she said. "It's pretty far away."

"Jones says she expected the quake swarm "to continue to bubble along, they're going to get a bunch of 4s and 5s."

http://www.scpr.org/news/2012/08/26/34048/swarm-earthquakes-46-53-49-shake-brawley/

[Viva_La_Revolution]

16. according to the livecam, another just now. 4.8 nt

[Canuckistanian]

15. Yeah, what's up with that?

A few friends from California are concerned about so many alerts in such a short time.

[kimbutgar]

17. I live in San Francisco didn't feel earthquake but around between 3 & 4PM the air raid sirens went

off like a warning. Usually at 12 Noon on Tuesdays we hear these sirens. I ran inside to check the news. Maybe it was a warning of an earthquake that didn't happen.

[rks306]

19. Just curious

Are they fracking anywhere in the area.

[XemaSab]

23. There's some geothermal energy there

[slackmaster]

26. There is no oil or gas in the immediate area, but there are geothermal wells

The near-surface hot rock that makes the area prime for geothermal power is also less capable of handling seismic strain that is cooler rock.

[wordpix]

20. that's one place where buying real estate is real risky

[AsahinaKimi]

21. Northern Cali has been some what quiet of late..

in terms of larger quakes. I think after seeing what happened in Northern Japan, quake followed by a Tsunami, that worries me a little as I live pretty close to the Ocean. There have been quakes off shore of California, and all it takes is a big one to start that wave heading in this direction. I think its entirely possible we could have both in the future.

[dipsydoodle]

24. Geological Origins of the Southern California Earthquake Swarm of August 2012

Located on the boundary between two of the Earth’s tectonic plates, Southern California is seismically active and earthquakes of such magnitude are by no means unusual or unexpected. The earthquake swarm of the weekend of 26-27 August occurred in the Salton Trough, at the southern end of the notorious San Andreas Fault Zone. Its focus was close to the point where the plate boundary changes in nature.

Plates moving apart have created the Gulf of California. Image courtesy of Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC

To the north, the boundary is a transform fault along which the Pacific and North American continental plates move laterally relative to one another, causing friction and generating earthquakes. To the south, the boundary is a constructive boundary, where an ocean ridge (the East Pacific Rise) effectively reaches the shore. Here, rather than moving past one another, the two plates are moving apart. Extensional forces, which occur when the plates move apart, cause faulting and earth movements result. It is these extensional movements that have caused the Saltoun Trough.

Glancing at a map of Mexico and California makes it easy to see where this rift occurs – the ridge runs up the middle of the Gulf of California. Over a very long time, this process is likely to split Baja California away from the main continent, with the Gulf eventually evolving into a new ocean.

http://decodedscience.com/southern-california-earthquake-swarm-of-august-2012/17290