The New Madrid Seismic Zone is a huge fault in the Mid-West that runs roughly between St. Louis, Missouri and Memphis, Tennessee.  The geology in the Central US makes earthquakes in that area much more intense and widespread. Sandy soil amplifies shock waves and creates an effect called �liquefaction� � or the soil behaving as a liquid, producing tremendous damage to structures. This does not readily happen on the West Coast. Map shows comparison between 2 sets of comparable quakes (by magnitude).

  The significant quake in the area occurred in 1886.  However, the most serious series of earthquakes in the area was in 1811-12 (4 major quakes within 3 months in winter � 7.7, 7.0, 7.3, 8.0. on the Richter Scale of measurement for earthquakes).  When this occurred, church bells rang across the U.S. including Massachusetts due to the ground vibration.� the second weakest of these being the comparison in lower map. There appears to be a 200 year cycle of quakes in region � some debate on this � but a serious consideration (we are at 194 years since last significant series). There were a total of over 2,000 significant aftershocks during the events between 1811 and 1812.