Where was the largest-magnitude earthquake in the 50 states, and when was it?
The strongest recorded earthquake in the United States was near Prince William Sound, Alaska, on March 27, 1964. Measuring 8.4 on the Richter scale, it killed 131 people and caused a 50-foot tsunami that traveled 8,445 miles at 450 miles per hour. Tremors were felt in California, Hawaii, and Japan. However, another earthquake (or series of earthquakes), which was not recorded, is considered by many to have been the most severe in U.S. history. That was the New Madrid (Missouri) Earthquake, which started in December 1811 and lasted until March 1812. It shook more than two-thirds of the United States and was felt in Canada. It changed the level of the land by as much as 20 feet, altered the course of the Mississippi River, and created new lakes west of Mississippi and Tennessee. Because the area was so sparsely populated, there was no known loss of life.