It has been noted that the range of yesterday’s earthquake in Virginia was considerably higher than any quake that occurs in California, as “shakes” were felt as far north as Maine and as far south as South Carolina.
Apparently there’s a pretty basic reason for this: the difference in crust. The main factors that determine how far a seismic wave propagates are temperature and density. In the East, the infrequency of earthquakes, along with the the crust’s being older, make it colder and denser. Meanwhile, since the San Andreas Fault is tectonically active, the crust has stretched, making the ground below much thinner and susceptible to hot rock from the mantle. This obviously warms the area up. So the colder and denser it is, the further the seismic wave can move. Apparently the author of the link is a hydrogeologist, so I’ll take his word for it.
It sounds like sixth grade science, but I didn’t really know much about this, so I feel a bit smarter today. Also, after yesterday, I realized something: cold weather and snow are to the people in the East as earthquakes are to those in the West.
