Earthquakes in Ohio seem to be felt over a larger area than a similar-size earthquake in California. Why is this?
In general, earthquakes in the eastern US have a felt area about ten times larger than a comparable size earthquake in the western US. This is a phenomenon that seismologists call attenuation. In Ohio, the rocks are nearly flat-lying, brittle, and cold. These characteristics are favorable for seismic waves to travel longer distances without losing significant energy. In contrast, California earthquakes, for example, travel through less consolidated, warm rocks that are interrupted by mountain ranges and other features that tend to absorb (attenuate) seismic energy. Although larger earthquakes are much less common in the eastern US than in the west, there is concern that much more damage, over a larger area, would result from an eastern earthquake of moderate size.
Last update July 20, 2005