Hi All. Well now lets see what we have here. The quakes in the San Ramon area are mix of just about everything. They range from “strike slip”, to “strike slip with thrust fault component” to “strike slip on a down dipping fault.” To say this segment of the Calaveras fault doesn’t behave like other segments of the fault doesn’t really explain it.

The Calaveras fault behaves in different ways along its length. In some areas, like Hollister, the fault creeps slowly with only micro-earthquakes. Other areas, like Morgan Hill, have little or no fault creep and periodically experience moderate earthquakes every 30 to 40 years. Some areas, like the San Ramon Valley, have no fault creep and moderate earthquakes every 100 to 300 years. The last moderate quake was on 07/04/1861 and was an M>5.7 est. Many questions remain unanswered.

This recent swarm of quakes didn’t do a thing in the way of relieving any stress in the area. You would need just a little over 35,000 M>3.9 quakes to release the same amount of energy as one M>5.7 quake. They would also have to occur one right after the other. I don’t know about you, but I think I would prefer just the one M>5.7 as opposed to having a quake last more then an hour. I’m not sure which would break first. My nerves or the foundation.

Dr. David Schwartz of USGS said that USGS would be watching this segment of the fault closely for the next couple of weeks. I have a feeling they won’t be the only ones watching it.

Another note worthy item is the creep in the San Juan Bautista (SJB) data. I’m sure there is a connection here, but I’ll be hanged if I can find it. Not even sure if I would understand it if I did find it. Anyway there was some acceleration in creep before the San Ramon quakes started. There has been a third acceleration in creep at a third site in the SJB data. The problem here is that none of them are connected to the Calaveras fault. I know the area between the San Andreas fault and the Hayward fault is a block. The same thing applies to the area between the Hayward fault and the Calaveras fault so that may be where the connection is.

I haven’t the foggiest idea as to what this means for the Bay Area in general, but I have this nagging feeling that were a lot closer to have a major quake in the Bay Area then anyone wants admit, or to accept. If I remember correctly Petra and I said it would be most likely in the next 5 years. I think we said that about 2 years ago. Take Care…Don in creepy town