PREDICTING EARTHQUAKES

August 18, 2004
		In recent years, scientists have been moving ever closer to one day being able to predict when and where a major earthquake could occur. A leading scientist in earthquake prediction answers your questions about the latest developments in the field.

Online NewsHour Special Report: Predicting Earthquakes Forum Introduction What is the difference between a "return interval" and a "recurrence interval"? Seismologists study earthquakes, but who studies how to mobilize society for disaster? Why is it that the New Madrid Fault is very rarely mentioned in quake discussions? If people could turn on their TVs to find out an earthquake was coming, wouldn't there be widespread panic? Are we going to have a 19-year quake cycle here in California? What are the chances of a major earthquake through the mid-U.S.A., where none has occurred since the early 1800s?	Kenlyn Blecker of Solvang, Calif., asks: What are the chances of a major earthquake through the mid-U.S.A., where none has occurred since the early 1800s? Dr. William Ellsworth responds: The New Madrid seismic zone has been the focus of intensive study by the U.S. Geological Survey's Earthquake Hazards Program for over a decade. Studies of pre-historic earthquakes in this region show that the average time between large events, such as occurred in 1811-1812 is about 500 years. Accordingly, there is approximately a 1 in 10 chance of a regionally devastating earthquake in the next 50 years. The possibility of such an event plays a significant role in the building code requirements for new construction. The last major earthquake to strike the New Madrid region was on Oct. 31, 1895 with an estimated magnitude of magnitude of 6.2. The last major earthquake to strike the East Coast occurred near Charleston, S.C. on Sept. 1, 1886 with an estimated magnitude of 6.9.