Hi Lowell. The two quakes you are referring to occurred on the Rodgers Creek/Healdsburg fault.

The one on 09/22/1999 was the Bennet Valley quake. It occurred at 38.39N/122.63W.

The other one on 01/18/2000 was north of Healdsburg and was again on the Rodgers Creek/Healdsburg fault. It was a 4.3. By the way there were 4 quakes in that area in Jan. 2000. They are almost all in the same location. The first one was a 4.0 at 38.84N/122.83W on 01/06/2000. The second one was a 4.4 at 38.76N/122.91W on 01/10/2000. The third one was a 4.6 at 38.77N/122.91W on 01/11/2000. The fourth one was a 4.3 at 38.75N/122.91W on 01/18/2000.

When I do a search I look only for quakes that are associated with a particular fault. The Bodega Bay quake appears to have been on the San Andreas fault so I kept my search for the San Andreas fault. I feel that I get a better idea as to what is occurring along a given segment of a fault by doing it this way.

This can have some drawbacks if you’re not familiar with the fault. If the fault has a sharp dip to it the quakes can appear to be located on another fault, or not on a fault at all. Take Care…Don in creepy town