| The Great New Madrid Earthquake |  |
New Madrid Earthquake
Roman numerals indicate estimated Modified Mercalli intensities for a 6.5 magnitude earthquake.
Based on maps in W. Atkinson, 1989, The Next New Madrid Earthquake, Southern Illinois University Press
The recent earthquake which struck Kobe, Japan, resulted in the loss of over 5000 lives and millions of dollars in property. However, large parts of the United States are also subject to large magnitude quakes - quakes which could be far more powerful than the Kobe quake! Although we tend to think of California and Alaska as the places where most of our earthquakes occur, the fact is that the central U.S. has been the site of some very powerful earthquakes.
In the past three centuries, major earthquakes outside of California and Alaska generally occurred in sparsely-settled areas, and damage and fatalities were largely minimal. But some took place in areas that have since been heavily built up. Among them are three earthquakes that occurred in 1811 and 1812 near New Madrid, MO. They are among the Great earthquakes of known history, affecting the topography more than any other earthquake on the North American continent. Judging from their effects, they were of a magnitude of 8.0 or higher on the Richter Scale. They were felt over the entire United States outside of the Pacific coast. Large areas sank into the earth, new lakes were formed, the course of the Mississippi River was changed, and forests were destroyed over an area of 150,000 acres. Many houses at New Madrid were thrown down. "Houses, gardens, and fields were swallowed up" one source notes. But fatalities and damage were low, because the area was sparsely settled then.
The probability for an earthquake of magnitude 6.0 or greater is significant in the near future, with a 50% chance by the year 2000 and a 90% chance by the year 2040. A quake with a magnitude equal to that of the 1811- 1812 quakes could result in great loss of life and property damage in the billions of dollars. Scientists believe we could be overdue for a large earthquake and through research and public awareness may be able to prevent such losses.
Los Angeles can expect to be mightily damaged by movement on the San Andreas Fault, or the Newport-Inglewood or other neighboring faults, most probably within the next 25 years. But the Eastern and Midwestern states also face ground shaking of colossal proportions, repetitions of such known upheavals as the 1886 Charleston, S.C., quake, the 1755 Boston quake, and the Jamaica Bay quake hundreds of years ago on New York's Long Island. The granddaddy of them all was the 1811-1812 series of three great quakes on the New Madrid Fault (halfway between St. Louis and Memphis beneath the Mississippi), which shook the entire United States. The next time the New Madrid Fault produces such a quake, it is estimated 60 percent of Memphis will be devastated, leaving $50 Billion in damage and thousands of dead in its wake. Memphis, you see - like Armenia - has looked down the barrel of a loaded seismic gun for decades, but has done virtually nothing to move out of the crosshairs.