[Island Chris]

There was a M4.1 strike-slip earthquake near the SE coast of Salton Sea California, with a little swarm a few km east. This area is of interest and some concern because the San Andreas fault projects near or east of here (very close). The depth with the focal mechanism is given as 5 km. There is a geothermal energy field in this area, and they produce hot water or steam and I think reinject it. This is the same principle of what is causing all the quakes in Oklahoma and nearby. But, it may be different to some extent in this field if it is in young sedimentary rocks. The heat flow is very high here: there is metamorphism a couple of km down in a scientific core hole in this area. I think there are also little young volcanoes.

Over the years I have been posting here, there are swarms now and then and these have not been followed by a big quake.

Chris

Chris

[Skywise]

(05-21-2015, 01:27 PM)Island Chris Wrote: There was a M4.1 strike-slip earthquake near the SE coast of Salton Sea California, with a little swarm a few km east. This area is of interest and some concern because the San Andreas fault projects near or east of here (very close). The depth with the focal mechanism is given as 5 km. There is a geothermal energy field in this area, and they produce hot water or steam and I think reinject it. This is the same principle of what is causing all the quakes in Oklahoma and nearby. But, it may be different to some extent in this field if it is in young sedimentary rocks. The heat flow is very high here: there is metamorphism a couple of km down in a scientific core hole in this area. I think there are also little young volcanoes.

Over the years I have been posting here, there are swarms now and then and these have not been followed by a big quake.

Chris

Chris

To my untrained eye, the south end of the Salton Sea looks to be a spreading center - the northern most one of the many that string up along the Gulf of California from further south at the spreading ridge between the Pacific and Cocos plates.

As such, I'm not so sure quakes in this specific area are much of a threat to triggering the southern San Andreas.

On the other hand, if the quakes occurred to the north east, along the northeast shore of the Salton Sea where the San Andreas distinctly traces.... errr... I'd be worried.

Brian

[Island Chris]

Brian,

as you know, you are correct about it being a spreading center. It forms a very different kind of crust than a mid-ocean spreading center because of the very high sediment input.

Yes, I was thinking that it might be of more concern if the quakes were deeper, and away from what is presumably a hot, weak, and thinner crust.

On the other hand, how a future southern San Andreas quake might start is not likely to be known or understood.

Chris

[Skywise]

(05-22-2015, 12:09 AM)Island Chris Wrote: On the other hand, how a future southern San Andreas quake might start is not likely to be known or understood.

Yep. Whether it's my amateur input or a seasoned expert, we just don't know. The southern SA has not ruptured in recorded history. About all we have to go on right now is paleosesmological trench work.

But I know a southern SA quake would be bad. I presume you saw those shake movies of a hypothetical rupture starting in the south and moving north? Yikes. And I live here.

Brian

[KathyKeegan]

(05-22-2015, 02:26 AM)Skywise Wrote:

(05-22-2015, 12:09 AM)Island Chris Wrote: On the other hand, how a future southern San Andreas quake might start is not likely to be known or understood.

Yep. Whether it's my amateur input or a seasoned expert, we just don't know. The southern SA has not ruptured in recorded history. About all we have to go on right now is paleosesmological trench work.

But I know a southern SA quake would be bad. I presume you saw those shake movies of a hypothetical rupture starting in the south and moving north? Yikes. And I live here.

Brian

And, in case you haven't noticed, Salton Sea is feeling perky.

[KathyKeegan]

(05-22-2015, 07:56 AM)KathyKeegan Wrote:

(05-22-2015, 02:26 AM)Skywise Wrote:

(05-22-2015, 12:09 AM)Island Chris Wrote: On the other hand, how a future southern San Andreas quake might start is not likely to be known or understood.

Yep. Whether it's my amateur input or a seasoned expert, we just don't know. The southern SA has not ruptured in recorded history. About all we have to go on right now is paleosesmological trench work.

But I know a southern SA quake would be bad. I presume you saw those shake movies of a hypothetical rupture starting in the south and moving north? Yikes. And I live here.

Brian

And, in case you haven't noticed, Salton Sea is feeling perky.