U.S. EARTHQUAKE HISTORY
The New Madrid earthquake of December 1811, one of the largest in U.S. history, had its epicenter in Missouri, and ended up ringing church bells in Boston, more than 1,000 miles away. The New Madrid Fault zone lies within the central Mississippi valley extending from northeastern Arkansas through southeastern Missouri, western Tennessee, Kentucky and southern Illinois. Indeed, four small quakes in mid-December 2009 were felt in Arkansas, Missouri, Tennessee and Kentucky, even though the highest magnitude was only a 3.1. No injuries or property damage were reported in the U.S. from the December 2009 seismic activity.
Since 1900, earthquakes have occurred in 39 U.S. states. Minor earthquakes, for instance, struck states such as Illinois and Nevada in 2008. There has not been a major quake on the U.S. mainland, however, since the 6.7 magnitude Northridge, California, event in January 1994.
Nonetheless, California remains the U.S. state most at risk of a major earthquake. A huge quake is more likely in Southern California than in Northern California over the next 30 years, according to a 2008 study compiled by experts from the U.S. Geological Survey, USC’sSouthern California Earthquake Center and the California Geological Survey. The study also predicted, in looking at the 30-year probability of one or more events greater than or equal to the magnitude of the Northridge quake hitting California, that there is a 99 percent chance that at least one earthquake meeting that criterion will occur.
The 1994 Northridge earthquake and the 1989 6.9 magnitude Loma Prieta quake that struck the Oakland-San Francisco area during that year’s World Series were two of the three most costly earthquakes in U.S. history as defined by insured losses. In 2011 dollars, Northridge caused an estimated $23.2 billion in insured losses, placing it first on the list, while the Oakland-San Francisco quake resulted in insured losses totaling a little over $1.7 billion, ranking third in that category. The San Francisco earthquake of 1906 ranks as the second costliest in U.S. history, causing insured losses equal to $4.1 billion in 2011 dollars. Yet, nearly 20 years after the Northridge, California, earthquake, only about one in eight California residents have their homes or businesses insured for earthquake-caused property losses.