Hi All. I have been snooping around a lot here of late and asking some questions along the way. What I’ve found has proved to be interesting. At least to me anyway. The one thing I did find is about a fault no one has really heard anything about until just recently. Pat (Petra) first introduced me to the fault more then a month ago and for that I thank her. She took me to it so I could see it first hand for myself. It’s not a very impressive fault as faults go, but when you look at the surrounding area as a whole you can see there has been some pretty impressive movement in the past.

One of the things I found interesting is the Hayward-Rodgers Creek fault that runs from Fremont to Santa Rosa, with a 32 percent probability of a 6.7 or larger earthquake, and has the highest odds for any Bay area fault for having a major quake. In 1898 a magnitude 6.5 Mare Island earthquake that would be destructive to infrastructure in the northern San Francisco Bay area occurred. It is felt that a 27-mile rupture of the Rogers Creek fault could generate a magnitude 7 earthquake and with displacements averaging 3 feet. The other thing that I found is that there is a northern segment of the Rodgers Creek Fault know as Healdsburg thus the name Rodgers Creek/Healdsaburg Fault. The last study made of this fault show that for all purpose and intent that it is locked up (less then 2mm of movement per year) The Rohnert Park quake on Wednesday, Sep 22, 1999 had a magnitude of 4.2ML and was on the Rodgers Creek fault. As you can see the 2mm creep per year is no longer valid. The recent mini swarm of quakes near the town on Windsor is associated with the Healdsburg portion of the fault.

The other thing I found interesting is that the overall movement of the fault was that of a reveres-slip. This is kind of interesting in that the Bolinas quake and the more recent Yountville/Napa quake also showed the same trend. The creep data for the Bay Area indicates that a reverse-slip started 4 days before the Yountville/Napa quake. Unfortunately I wasn’t paying attention to the data before the Bolinas and Rhonert Park quakes so I don’t know what kind of creep occurred before those quakes.

I guess what all this boils down to is that there is a large quake building for the Bay Area. I have no timing on this, but do feel that it will be along the Rodgers Creek Fault. It appears that the Rodgers Creek Fault is moving and that it is just a matter of time before there is a major quake on it, which I feel, will be sooner rather then later. Take Care…Don in creepy town.