Hi All. Looking at the “moment tensor solution” and the “first motion mechanism” for the M=5.1 Obsidian Butte quake they all have one thing in common. There was some downslip. This being the case then more then likely the quakes are being caused by some extension with some lateral slip. This would be in keeping with the Gulf of California, or Baja, which has been pulled away from Mexico. Some of the other quakes that have been occurring in the area show that they are “pure strike-slip.” There were a couple that have been “pure normal” quakes. It may be that the quakes are occurring on different faults. That is a possibility but not sure as to how probable this would be.

So far the number of M=3.0+ and M=4.0+ and the M=5.0+ may have released enough stress to prevent an M=6.0. The flaw with that thinking however is that an M=6.0+ could still occur, but it would be a weak M=7.0+. Also, for the same reason it doesn’t rule out the possibility of an M=8.0+ quake assuming that all of these quakes are foreshocks.

The current theory, although not accepted by all is that in 15 or 20 million years the Gulf of California could one day extend all the way north to Oregon through the Owens Valley and what ever other path it might take such as the Walker Lane Belt. I must admit though that there is a lot of controversy over where the Walker Lane Belt might be headed for, or where its at now, or that it even exists. Most of the geologist I have talked to as well as my current thinking is that it runs through Portola, California, Burney, California, the Mount Lassen area and maybe, just maybe it might already be in the Mount Shasta area.

I will have to admit though that there is scant little evidence for the Mount Shasta area. Being an amateur geologist/seismologist I don’t have peer pressure to contend with. I don’t have to worry about rubbing those above me the wrong way and maybe getting myself ostracized for having some weird ideas. It also has it draw backs in that I don’t have access to the data the professionals have. I think I will have to go and think some more about what I’m thinking about. Take Care…Don the old speculator.

• FIRST-MOTION FOCAL MECHANISM