Hi John. Thanks a bunch. I was aware of the chart, but the magnitude scale never occurred to me.

The M>5.0 equivalent that I was using was taken from one of the tests at the Nevada test site. I believe they were measuring the “L and “R” waves which causes the most damage at the surface, but also dissipate much faster then the “P” and “S” waves. Correct me if I’m wrong.

Anyway the database is way to small to draw any conclusions of any kind. There is nothing to compare it to. It’s much like the 22 year cycle for a M>6.0 quake occurring at Parkfield. There were 6 quakes in the area. 1857, 1881, 1901, 1922, 1934, 1966. This averages out to one quake every 22 years, but as one can see they didn’t occur every 22 years. It is now 37 years since the last one occurred in the area. Of course it could be said that the Coalinga quake in 1983 was the quake they were looking for even though it occurred about 20 miles to the east and on a different fault. It could also be said that the quake disrupted the cycle at Parkfield. The truth is that I don’t think anyone really knows. Take Care…Don in creepy town