Hi All. While looking for that 30-year scientific time frame that has been used from time to time I came across this little article about the Yountville quake of 3 Sept. 2000. Take Care…Don in creepy town

The M5.2 event is the largest earthquake in this area since 1969 when two earthquakes, magnitude 5.6 and 5.7, struck Santa Rosa about 80 minutes apart. These earthquakes are associated with the Rodgers Creek fault system.

In fact, these 3 events are the only earthquakes with magnitude greater than 5.0 to hit the region 50-60 mi north of San Francisco Bay since 1906. However, in the past year there have been several magnitude 4 or greater events in this same region

1) A magnitude 4.7 event near Bolinas on 8/17/99.

2) A magnitude 4.3 event south of Santa Rosa on 9/22/99

3) A series of 3 earthquakes, magnitudes 4.0, 4.2, 4.0 near Cloverdale between January 10-18, 2000

It is not clear whether the increase in seismicity in this region reflects the end of a long period of seismic quiescence. If so, then this would indicate that the levels of stress are perhaps sufficiently high that larger quakes could be expected soon for the region. A similar seismicity pattern was observed in the 50-year period preceding the 1906 earthquake. However, there is too little data available on which to alter the formal probabilities for the seismic hazard in this region. Clearly, had such an argument been put forth after the two earthquakes that rocked Santa Rosa in 1969, the subsequent 30 years of earthquake activity in this region would have proven the argument to be flawed.

• Bay Area Quakes