Earthquakes: Risk, Monitoring, Notification, and Research

Publication Date: February 2007

Publisher: Library of Congress. Congressional Research Service

Author(s):

Research Area: Environment

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Abstract:

Close to 75 million people in 39 states face some risk from earthquakes. Seismic hazards are greatest in the western United States, particularly California, Alaska, Washington, Oregon, and Hawaii. The Rocky Mountain region, a portion of the central United States known as the New Madrid Seismic Zone, and portions of the eastern seaboard, particularly South Carolina, also have a relatively high earthquake hazard. Compared to citizens of other countries, relatively few Americans have died as a result of earthquakes over the past 100 years, but the country faces the possibility of large economic losses from earthquake-damaged buildings and infrastructure. Until Hurricane Katrina in 2005, the 1994 Northridge (CA) earthquake was the costliest natural catastrophe to strike the United States; some damage estimates were $26 billion (in today's dollars). Estimates of total loss from a hypothetical earthquake of magnitude more than 7.0 range as high as $500 billion for the Los Angeles area.

Given the potentially huge costs associated with a severe earthquake, an ongoing issue for Congress is whether the federally supported programs aimed at reducing U.S. vulnerability to earthquakes are an appropriate response to the earthquake hazard. Under the National Earthquake Hazards Reduction Program (NEHRP), four federal agencies have responsibility for long-term earthquake risk reduction: the U.S. Geological Survey (USGS), the National Science Foundation (NSF), the Federal Emergency Management Agency (FEMA), and the National Institute of Standards and Technology (NIST). They variously assess U.S. earthquake hazards, send notifications of seismic events, develop measures to reduce earthquake hazards, and conduct research to help reduce overall U.S. vulnerability to earthquakes.

Congress established NEHRP in 1977, and its early focus was on research that would lead to an improved understanding of why earthquakes occur and to an ability to predict them accurately. Congress most recently reauthorized NEHRP in 2004 (P.L. 108-360), and designated NIST as the lead agency, to create better synergy among the agencies and improve the program. Understanding has improved about why and where earthquakes occur; however, reliably predicting the precise date and time an earthquake will occur is not yet possible. Research may eventually lead to an ability to predict earthquakes, but the focus of NEHRP now has shifted towards improving the nation's ability to prepare for earthquakes and to minimize losses when an earthquake occurs.

Under NEHRP, the USGS has responsibility for conducting targeted research to improve the basic scientific understanding of earthquake processes. USGS research has produced, for example, a relatively new product called ShakeMap. ShakeMap provides a near real-time map of ground motion and shaking intensity and portrays the extent of damage following an earthquake. NSF supports more fundamental research -- it distributes research grants and coordinates programs -- that leads to a better understanding of crustal processes that cause earthquakes around the globe. NSF recently initiated a major project called EarthScope to study the structure and evolution of the North American Continent.