Earthquakes in the interior

I have the Earthquake Watch widget on my iGoogle page and I noticed an oddity today: a quake in Missouri. There’s always lots of activity in Alaska and the west coast, but something in the interior seems to be rarer. I went to the USGS earthquake site for the map of the US and discovered there was more than just Missouri in the past week. There were also tremors in Tennessee, Alabama, Mississippi and Arkansas.
In the past seven days, there were 764 quakes reported in the U.S.

