Hi All. The quake cluster near Viola got me to thinking about whether or not there could be other locations near by that has had a cluster similar to the current one.

I found one that had 51 quakes although there could be more, as I’m not sure of the location for the center of this cluster. I used a 20 mile radius of the largest quake near Viola. The quakes stated on 12/28/1977 and ended on 12/31/1977. The location of these quakes was about 16 miles NE of the current cluster. Both clusters are west of Lassen Volcano.

The largest quake was a M>2.9 the smallest was a M>1.0. There were undoubtedly smaller ones, but this was the smallest quake I started my search with.

Were the quakes in 1977 volcanic in nature? As there are no moment tensor solutions to any of the quakes it’s hard to say. However the moment tensor solution for the M>3.1 quake near Viola shows it to be a strike slip on a down dipping fault plane. I don’t think this is the type of quake one would see if the movement of magma was causing the quakes. This plus the fact that the quakes from start to finish are too fast to be associated with magma. Magma is slow moving so the quakes would last longer.

There are 9 cinder cones in the area. Most appear to be west of Mt. Lassen. There are a couple north of Mt. Lassen. There are also some unnamed faults west of Mt. Lassen. Most are considered extinct, but not inactive. Take Care…Don in creepy town