While Alaska and California are known for U.S. tremors, one area that continues to attract study and concern is the so-called New Madrid, Missouri, area, considered the second most active quake region in the country. There, four violent tremors that some scientists believe were greater than the 1964 Alaska quake and larger than the 1906 San Francisco disaster rocked an area encompassing Missouri, Arkansas, Illinois and Tennessee in 1811 and 1812. Tremors were felt over 2 million square miles of the country. Damage to property was slight because the area was sparsely settled in those days. But NEIC's Person says that if a quake of that magnitude were to strike again in the region, the city of Memphis, for example, would be devastated.
Earthquakes are virtually inescapable in the continental United States.
They occur in most states, with Florida and North Dakota recording the fewest. California with its San Andreas Fault is prone to earthquakes. Here is a result of the earthquake that hit the Northridge area of Southern California in 1994. Chile's 1960 quake of 9.5 magnitude is still regarded as the world's largest known quake in recent history, according to CERI archives. Another 17 percent of the world's quakes occur in the Alpide belt, which stretches from Java through the Himalayas to the Mediterranean and out into the Atlantic.