It was close to the Malibu Coast fault. One nodal plane of the strike-slip focal mechanism strike ENE and is vertical. The Malibu coast fault strikes E-W onshore and probably dips north, at least to the east of the quake. to the west, it bends about 20 deg and strike ENE and dips steeply north. We can only interpret it in its upper 3 km or so so we are not sure what it does farther down. This is based on my own mapping with students using a lot of industry seismic reflection data. It continues off to the WSW where it must hook up with the Santa Cruz Island fault. The Santa Cruz Island fault is mainly a left-lateral fault. The offshore Malibu Coast-Santa Cruz Island fault is probably near pure left-lateral. Onshore, the Malibu Coast fault picks up more and more reverse component due tot he bend in its strike and probably due to clockwise rotation of the block to the north.

The offshore Malibu Coast fault is wrong in the SCEC Community Fault Model: they just extrapolated the fault due west and did not use the 20 deg bend in strike. This is partly because for unknown reasons they did not use a representation I provided them probably 5 years ago, and more recently, I have simply not had time to provide them a representation based on the much dense sesismic data now available. I'm spending a lot of my time instead trying to get the major revisions done for a long-suffering manuscript I've been talking about here for years on the Palos Verdes area.

Anything else you want to know about this fault system? I've done a lot of work on the offshore parts and the islands.

Guess I better email a Cal State Northridge student and his advisors about this quake: the student relocated seismicity to use in projecting the shallow mapping to depth.

Chris

• Malibu Coast quake