[Island Chris]

As Brian and some of our people who used to post know, this sequence has similarities to the 1987 Ellmore Ranch-Superstition hills pair. Ellmore Ranch was a M6.2 left lateral quake that was followed by about a half day by a M6.7 (?) right-lateral quake. I talked to seismologist Craig Nicholson after the M6.4 and he said the M6.4 July 4 was not that simple. It had a focal mechanism for strike slip. Most of the aftershocks outlined a NE-SW lineament which is the left-lateral plane. But there were also quakes along a shorter NW-SE right lateral plane. Looks like that NW-SE right-lateral motion triggered the M7.1 on the same fault. Hmm, may have to check SCEC and IRIS web sites to see if that was a known, named fault.

Brian, I can post more if you and other smart people post on earth sciences. A lot has happened with me the last 4 years.

Chris