Where is the "San Andreas Elbow"? I can't find the term with a google search.
more at Daily Mail link above, from the 04.28 online issueSouthern Californians were shaken out of bed Saturday morning by a small earthquake that rattled homes across the Inland Empire region and caused buildings to sway in downtown Los Angeles.
The magnitude 3.8 earthquake struck at 8:07 a.m. The U.S. Geological Survey said it was centered about two miles northwest of Devore, in San Bernardino County.
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'It felt like a sonic boom,' said Letty Salgado, a server at Papa Tony's Diner in San Bernardino.
'Everybody was startled. Customers all looked at each other, then went right back to their breakfasts. It was real quick.'
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Yes, that's normal.Customers all looked at each other, then went right back to their breakfasts. It was real quick.'
OK that was weird- anyone else feel it?
Never felt one quite like that before. Jolting not rocking.
Sorry, Nova, I thought it was a more common term. One of my geology instructors (lo these many years ago now) used that term, and it's stuck.
The "Elbow" is the area around Frazier Park, inland from Santa Barbara. It's where the north/south line of the SAF bends slightly towards the east, and then continues down into Mexico.
It's a spot that a lot of folks historically believe will be a fracture of the transform fault will break in a catastrophic eq, because at some point in the past, for it to have bent east like that, there was a fracture there. Almost like the bottom is pushing up past the top, even though this is not a thrust fault.
There are also a whole lot of "little" faults in the San Fernando Valley, on an east west orientation, and those may be remnants of an earlier fault break at the elbow, or stress faults from the lower part of the state creating pressure on the area of the elbow.
Hope that makes some sense...thanks for asking. I didn't realize that it wasn't as common as I thought it was. I'll do better next time.
Best-
Herding Cats
No, thank YOU. I've been in Southern California for 27 years now and had never learned all that. I wish I'd taken geology in California rather than in Florida! LOL.
Florida has a lot of interesting geology, mostly having to do with both the purported asteroid impact as well as erosion and sub-sea level pressure and formation. And of course it's actual components of ground.
But California is very interesting; we have all of the same things that FL does, except the underbed rock is somewhat different. And we're much "younger" than FL, too, in the grand scheme of things. We have cliffs, mountains, and valleys (and where you have these three in "close" conjunction, you have fault lines). What is intriguing is that we have mountain ranges that go cross-wise near each other, and also near an ocean, and that shore has some fairly large cliffs. So it's apparent that there is a lot of underground activity here.
Having been in quite a few of the larger eqs in California, I took some geology classes. There was some very interesting things taught, and I loved the field trips we took. I didn't enjoy learning about how dangerous it really is here regarding earth movement, but then again, it's dangerous everywhere; I don't know one place that doesn't have it's own natural disaster inherent to the region.
I will say, even though I've watched eq's for years on USGS, something does seem to be happening. It's almost as if the southern active regions (just north of Australia; the Indonesian area, Fiji/Tonga, and so on) seem to be moving, and it looks like they're moving northward and eastward. '
Both of those movements put pressure on faults, such as Japan and Chile. Both of those areas seem to be either fracturing (e.g. Japan) or having mulitple eq's without severe damage (e.g. Chile), and also displacing things more northward/eastward (towards the Alaska Islands [almost always in motion]) and towards Mexico and the West Coast.
Like I said, I've watched quakes for years...but this is a very different pattern than I'm used to seeing. A whole lot more 5 and 5.5s almost on top of each other, and that has got to put the pressure elsewhere - and I just worry that since we're not "letting off steam" like we should, and like we've seen in Mexico and Chile.
Nothing to do but make sure one's emergency supplies are updated, right? So that's what I do.
Best-
Herding Cats
Yes, that's normal.
Honestly.
I joke about it: if it can make me move, it's over a 5. If it makes me move fast, it's over 5.5. But other than that...well...I just don't notice.
Best-
Herding Cats
No, thank YOU. I've been in Southern California for 27 years now and had never learned all that. I wish I'd taken geology in California rather than in Florida! LOL.