Although the earthquake that shook Boston, along with the rest of the East coast, today was unusual, it was not unexpected. The United States has a long history of seismic activity outside of California. But because there haven’t been many earthquakes recently, we've lost perspective. In fact, it’s worth noting that the biggest earthquake risk that the United States currently faces is nowhere near California, but rather in rural Missouri.
The most dangerous fault line in North America is located around New Madrid, Missouri, and runs in a T shape across parts of Arkansas, Tennessee, and Kentucky. There were a series of major earthquakes in this area that occurred in the winter of 1811-12 and ranged between 8 and 8.9 on the Richter scale. The tremors were so great that the Mississippi River flowed backwards and people screamed in terror in the streets of New York.
While another major quake in the New Madrid fault would likely only cause a repetition of the mild shaking we experienced today in New England, it would be devastating for much of the country. Major cities like St. Louis and Memphis that are in the vicinity of New Madrid do not have the necessary preparations for an earthquake. And even though New England is not a seismic hotbed, the fact that so many of Boston’s buildings are built of wood or bricks, or on landfill, means that even a small quake could do far greater damage here than a comparable one would do elsewhere. The mild tremors today should serve as a warning that earthquakes can happen anywhere in the United States — not just in California and on the Pacific coast — and that just because an event is not likely does not make it an impossibility.