While reporting that Haiti suffered a a 5.9 magnitude aftershock early today, eight days after a magnitude-7 quake destroyed Port-au-Prince, Chicago newscasters reminded listeners that the Central United States sits on the second largest zone of earthquake activity in the country: the New Madrid Seismic Zone (NMSZ).
As Californians who have seen their earthquakes’ destruction or been merely awakened by a tremor know, their state’s San Andreas Fault is part of the US’s largest seismic zone.
Running diagonally across Central United States is the New Madrid Seismic Zone named for the town of New Madrid, MO destroyed by an 8.3 moment magnitude scale earthquake, Feb. 7, 1812. The Wabash Valley Seismic Zone extends north from MNSZ into Illinois (see map). Earthquake epicenters and tremors have occurred and or have been felt in Illinois, Indiana, Missouri, Arkansas, Kentucky, Tennessee and Mississippi.
Indeed, micro-earthquakes of 2.3 to 2.4 magnitude occur every year along the zone. A 1.5 micro event occurred as recently as 1:35 p.m. (CST), Jan. 16, 2010 eight miles northeast of Portageville, MO. Among the micro-earthquakes reported in 2009 were a 2.3 magnitude event tat 4:52 AM (CDT), June 13, 2009 six miles south of Equality, IL, A 2.4 magnitude mircro-earthquake at 2:46 CDT, Sept. 6, 2009 five miles northeast of Bellmont, IL and a 1.7 magnitude event 3:15 a.m. (CST) Dec. 2.
That earthquakes can cause real damage in Central US was emphasized in a just released (January 2101 report fromthe Mid-America Earthquake Center at the University of Illinois, Urbana-Champaign and a U.S. Geological Survey fact sheet (2009-3071): “Earthquake hazard in the New Madrid Seismic Zone remains a concern.”
The NMSZ’s continued activity prompted a consortium of scientists working through the Mid-America Earthquake Center to assess the zone’s past and current activity with predictions for future earthquakes, their strength and range of destruction.
The report just released, said: “ Based on this history of past earthquakes, the USGS estimates the chance of having an earthquake similar to one of the 1811–12 sequence in the next 50 years is about 7 to 10 percent, and the chance of having a magnitude 6 or larger earthquake in 50 years is 25 to 40 percent.
The report listed severe earthquake-caused damages and urged urban centers, such as St. Louis, MO and Memphis TN, which could be severely impacted by an earthquake, to do an infrastructure assessment and follow through with a rebuilding plan.
For more info: Mid-America Earthquake Center