. This morning’s quake (3.7Ml) is ½ mile north of Petra’s study area and ¾ miles east of the Crane Creek Regional Park. This puts it on the Rodgers Creek fault. The distance from her home to this morning’s quake is 8.9054Km or just a little over 5 miles.

This is the fault that Petra and I have been watching for more then a year now. She has been watching it much longer then that. It is also the fault deemed by USGS as the number one fault for a major quake (7.1Ml) in the next 30 years.

However since making that statement some new facts have come to light concerning the Pinole fault. Age dating of sediments in San Pablo Bay shows that the Pinole fault has a recurrence interval of about 900 years. The Pinole fault in the northeastern San Francisco Bay area, formerly believed to be inactive, has had a history of repeated movement during the last 10,000 years. The Pinole fault may be a potential linking structure between the active Hayward and Rodgers Creek faults, thereby significantly increasing the potential rupture length and, hence, the maximum earthquake which may be generated by these faults. This could mean that the earthquake could be equal to the 1906 quake, or it could mean that it could be larger.

The earthquakes at Bolinas, Rohnert Park and Yountville have always bothered me in that they could be the weak links surrounding the Rodgers Creek fault.

The section of the Rodgers Creek fault running south from Rohnert Park to San Pablo Bay has not had a major quake on it since around 1600. Trenches dug across the fault indicate this, but there is also the possibility that the trenches were not dug in the right place. There has also been no measurable creep to speak of along this section giving an indication that it is locked tight. This study was done by the UCB a couple of years ago.

This morning’s quake should be considered a wake up, but I wonder how many are going to view it that way? Take Care…Don in creepy town.