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04-26-2015, 04:27 PM
I'm making a new thread for comparing Nepal to southern California, or for general discussion of California thrust faults. I made the figure below in 2008 and then did not use it except maybe on a SCEC poster.
The B-B' cross section goes from Palos Verdes Hills across Los Angeles to the San Gabriel Mountains. The horizontal scale is the same on the California cross section and the Nepal cross section. The vertical scales are also the same. The green curves are GPS velocity, and the California scale for that is two times the Nepal scale. The idea in the Avouac paper is that the GPS shortening is between the High Himalaya and Kathmandu (or was before the quake). But, earthquakes rupture far south of the area of GPS shortening to the outcrop of the Main Frontal thrust (MFT). Yesterday's may not have ruptured beyond about Kathmandu (??). The GPS shortening in Los Angeles has been near and just north of downtown. Our paper proposes that an earthquake might rupture far southwest of that area for the same reason as Nepal.
The idea is that the deep thrust system is creeping and the shallow part is locked. Between quakes, it is along the creeping to locked boundary that is shortening.
Chris
The B-B' cross section goes from Palos Verdes Hills across Los Angeles to the San Gabriel Mountains. The horizontal scale is the same on the California cross section and the Nepal cross section. The vertical scales are also the same. The green curves are GPS velocity, and the California scale for that is two times the Nepal scale. The idea in the Avouac paper is that the GPS shortening is between the High Himalaya and Kathmandu (or was before the quake). But, earthquakes rupture far south of the area of GPS shortening to the outcrop of the Main Frontal thrust (MFT). Yesterday's may not have ruptured beyond about Kathmandu (??). The GPS shortening in Los Angeles has been near and just north of downtown. Our paper proposes that an earthquake might rupture far southwest of that area for the same reason as Nepal.
The idea is that the deep thrust system is creeping and the shallow part is locked. Between quakes, it is along the creeping to locked boundary that is shortening.
Chris