Hi Martin. Using the data you provided I went to the catalog and looked up the largest quake to have occurred within your parameters. There was a 6.20M (estimated) on 04/12/1885 at 36.40-121.00. This puts the quake just a little south of the Pinnacles.

When I opened the search to include all quakes from 1973 to present there were 135 quakes of which there were two with a magnitude of 4.9M. These two are the largest in the present catalog. One was on 11/28/1985 and the other on 07/26/1988. The location of both quakes is almost the same. The first one was at 36.56-121.06 and the second at 36.56-121.18.

Just running a quick glance over the pages I would have to say that the area between the two above locations is a hot spot for earthquakes in that general area. Take Care…Don in creepy town.