Hi John. Have to agree. The reason we didn’t get the quake during KBs time period is that the stress in the area wasn’t close to breaking. Just because the time period passed without incident doesn’t mean the stress decreased. It is still there and it is still building.

I know he bases his predictions on the increase of moderate to strong earthquakes in a given area and I also know it would take 33 M>5.0 to equal one M>6.0, but I also feel that each quake could decrease the level of stress on a given fault. The decrease being in the form of not as much occurring this month as last month, or this year as opposed to last year.

The creep in the Hollister area is about 7mm per year, but it isn’t 7mm every year. If creep can vary so can the amount of stress. For about 6 months following the Loma Prieta quake the creep almost doubled. Movement did not occur between 1910 and 1929, judging from the amount of offset in two sidewalks that were laid in 1910 and 1929, and in a pipeline laid in 1929. Creep commenced sometime after 1929 and averaged 8 mm/yr. Between 1961 and 1967; the slip rate was about 15 mm/yr. Since 1979, two sites have been monitored in Hollister, one showing 6.6 mm/yr and the other, only 2.3 km northwest, creeps 12 mm/yr. The creep site in Hollister is at 7th Street and the one north of town is on Wright Road. The Sargent fault starts in the area of Wright Road, or maybe a little further to the north.

Trenching along the San Andreas Fault in the Bay Area shows there have been ten 1906 earthquakes in the last 3000 years. This averages out to one quake every 300 years, but they found that was one quake that occurred 100 years after one quake. Using that data that could mean we could have another 1906 earthquake on the San Andreas Fault anytime now, or we still have another 200 years. It could also take more then 300 years.

David Schwartz feels that the next major quake in the Bay Area is going to occur on the Rodgers Creek fault. Trenching shows an average of 250 years for a major quake on the fault with the last quake occurring around 1730 to 1760. I have also heard that it may have been in the mid 1600s when the last quake occurred. Which ever it might be my money is on the Rodgers Creek fault and on the segment between Santa Rosa and San Pablo Bay. Take Care…Don in creepy town