A Comprehensive View of the Earthquake Swarm in Southern California

First I would like to say that I realize there is already a popular thread going about the swarm, however I would like to offer a seperate thread with more of a comprehensive/scientific resource for those looking for historical information and links to scientific resources. I don't want to take away from the other, but instead offer a spot to go for data to back up the great exchange going on there. I know from experience that once a thread takes off it gets very difficult to offer links since the edit feature was changed awhile ago.

SO...

First, there is obviously a large earthquake swarm going on in Southern California. It is actually in a region known as the Brawley Zone...where three faults intersect, the San Andreas being one of them. Historically the zone has produced mag 7-8 quakes every 180 yrs, with the last one being in 1700. (do the math ) There is always that chance that IF a large quake came from this zone on the San Andreas, it could propagate North along the San Andreas Fault, and liquifaction is also a risk in that area.

For a current list of quakes go to the USGS Site

For a historical explanation for the Salton Sea area go HERE

A link to some brief info on the Brawley Seismic zone

Here is an article from the MSM: Series of small earthquakes rattles Southern California

Lastly, I have great suscess watching the quakes live in GEE...a program for live seismograph streaming. Here is a screen shot of a series of small quakes:




Also, to clear up some issues on perspective: The swarm is roughly 130 miles or so East of San Diego, so while there is concern (but not certainty yet) that this may be from the San Andreas, since it is under land there is NO concern of tsunamis.

The area is also prone to swarms, so while this is definitely worth watching and a bit worrisome, it certainly doesn't mean the big one is imminenet. Only time will tell!!

The swarm is roughly 130 miles or so East of San Diego, so while there is concern

Well it is only 35 miles away from the Salton Buttes Volcano field. vulcan.wr.usgs.gov...

The Salton Buttes are at the southeast end of the Salton Sea, in the Imperial Valley of southern California, approximately 165 kilometers ENE of San Diego.

That is something to be concerned about I believe.

Glad to see you back in action WC!

It does seem to be quieting down for the moment. I will take this as a good sign. Hopefully it blew some steam out and will go back to sleep for another 40 years.

Thank you

I agree that the volcano fields are a concern, thank you for bringing them up! I will do some more research and provide more info on them. I mentioned location in regards to the ocean because it seemed there were some people afraid about this swarm generating tsunamis, which it clearly is not.

The latest discussion right now is that these seem to be coming from an un-named fault located in between the others, and that if they migrate into the San Andreas it would be cause for greater concern. As of now, hoping it will just behave characteristic of other swarms and slowly die out.

Here is a link to a Great map of the current swarm

Here is a historical seismicity map of the area

ETA: DUH.... I now see TAs thread. So much easier to direct you there for a great theory involving the volcanic field: link to TAs thread

reply to post by westcoast


OK,,, I looked at the link you provided for map of current swarm,,, I'm sorry but, THE 33rd PARALLEL !!! I'm starting to hear that spooky music again. I do not mean any disrespect to your post, it's just that some stuff jumps out at me

As I mentioned in the other "swarm" post....

We should be thankful for all of these little pressure releases. If this is indeed a precursor to the "big one" it will be way smaller than it could have been by all of these little guys releasing steam....

stock up on water, first aid, canned good and a radio with batteries if you havent already...JUST IN CASE...

if you live along the west coast you have no excuse to have these things handy anyways....

BE SAFE!

Here is another view of the current swarm centered just north of Brawley. The smaller SW to NE trending group of quakes on the lakeshore is related to the geothermal plant. (except one or two microseisms from the current swarm)

This map, with a list of the quakes shown can be found at the CalVO monitoring page for Salton Buttes. It is interactive. The colors on the map below relate to depths. I've set it to show the past 30 days so as to include the micro activity from the geothermal plant.



I'm trying to stay awake to see if any interesting changes show up on the strainmeters for southern California when the data is next updated. You can follow it at this USGS link for the SoCal /Anza PBO strainmeters. Here is a link to there location, just northwest of the Salton Sea


I hope it shows no dramatic change.

Finally, nice to see you Westcoast.

reply to post by Olivine


As always, great stuff! Thank you for providing it. I'll be curious to see what those meters show too.

And thank you -