[ckissick]

The energy of the quake, in terms of "g", or percent gravity, varies not by the square of the distance, but by a very complicated equation. And there are several equations by several researchers. I use the average of 5 equations. It also depends on the soil or rock under the house. It's all very complicated, and I just use the equations. I'm not smart enough to derive any equations. Charles Richter is said to have been one of history's most intelligent people, up there with Einstein.

Alamo, BTW, sits atop a very interesting seismic zone, between the Calaveras fault and Concord fault. There seems to be some communication between the 2 faults, with small quakes centered very deep.