Quote:
Originally Posted by geonuc
Your OP addressed the unusual nature of the Reno area fault (deep hypocenter). Now the LA Times is reporting on a swarm of shallow quakes.
As you know, the Basin & Range is an extensional province, caused, I believe, from the effects of the shallow subduction of the Farallon plate. Extensional block faulting tends to run from shallow to moderately deep, does it not?
What's your take on this?
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I've read papers theorizing that the Farallon plate is a shallow angle, i.e. low angle, subduction. In the May issue of
Geology Bulletin; GSA Wells and Hoisch suggest that the extension is due to anatexis, delamination, of the bottom of the overriding NA plate. The Reno area is at the extreme northern edge of the Sierra Nevada range. The Luning thrust belt is half way across Nevada to the east, i.e. the basin and range is to the east. There are former accreationary island arcs to the west, i.e. California. Eight kilometers deep is not even close to the MOHO, so in that sense, shallow. I am certainly not in a position to express any opinion as to what is going on beneath Mogul, Nevada. I do believe we need to watch it closely for any clues as what kind of "readjustment" is occurring there.
The Earth does seem active right now. Can one area affect another? Plate tectonics says that it should. On Human time scales, I do not know.