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11-06-2014, 01:09 PM
OK, the graphic posted OK. The red arrows point to what I think are fault scarps.
If the EQ locations are any good, 20 km is a big area for a swarm, although the main activity looks like across a 5 km area. There has been a big debate about whether low-angle normal faults slip during large quakes: "low-angle" means dip less that 30 deg. Normal slip earthquakes are "supposed" to be on faults dipping 60 deg, but the big global ones dip 40-50 deg mainly. There is even a debate in the USA Basin and Range whether some of the observed giant flat faults are faults or bases if mega-landslides. I checked focal mechanisms of 3 of the larger quakes and they were normal slip with some oblique motion.
This area is remote and I wonder how much is known?
I'll email UCSB professor Phil Gans this figure and see if he has anything to say.
Chris
If the EQ locations are any good, 20 km is a big area for a swarm, although the main activity looks like across a 5 km area. There has been a big debate about whether low-angle normal faults slip during large quakes: "low-angle" means dip less that 30 deg. Normal slip earthquakes are "supposed" to be on faults dipping 60 deg, but the big global ones dip 40-50 deg mainly. There is even a debate in the USA Basin and Range whether some of the observed giant flat faults are faults or bases if mega-landslides. I checked focal mechanisms of 3 of the larger quakes and they were normal slip with some oblique motion.
This area is remote and I wonder how much is known?
I'll email UCSB professor Phil Gans this figure and see if he has anything to say.
Chris