EarthquakesMore than 143 million Americans at risk from earthquakes

Published 23 April 2015

More than 143 million Americans living in the forty-eight contiguous states are exposed to potentially damaging ground shaking from earthquakes, with as many as twenty-eight million people in the highest hazard zones likely to experience strong shaking during their lifetime, according to new research. The research puts the average long-term value of building losses from earthquakes at $4.5 billion per year, with roughly 80 percent of losses attributed to California, Oregon, and Washington. By comparison, FEMA estimated in 1994 that seventy-five million Americans in thirty-nine states were at risk from earthquakes. In the highest hazard zones, the researchers identified more than 6,000 fire stations, more than 800 hospitals, and nearly 20,000 public and private schools that may be exposed to strong ground motion from earthquakes.

More than 143 million Americans living in the forty-eight contiguous states are exposed to potentially damaging ground shaking from earthquakes, with as many as twenty-eight million people likely to experience strong shaking during their lifetime, according to research discussed at the annual meeting of Seismological Society of America (SSA) held this week in Pasadena, California. The report puts the average long-term value of building losses from earthquakes at $4.5 billion per year, with roughly 80 percent of losses attributed to California, Oregon, and Washington.

“This analysis of data from the new National Seismic Hazard Maps reveals that significantly more Americans are exposed to earthquake shaking, reflecting both the movement of the population to higher risk areas on the west coast and a change in hazard assessments,” said co-author Bill Leith, senior science advisor at USGS. By comparison, FEMA estimated in 1994 that seventy-five million Americans in thirty-nine states were at risk from earthquakes.

An SSA release reports that Kishor Jaiswal, a research contractor with the U.S. Geological Survey (USGS), presented he research conducted with colleagues from USGS, FEMA and California Geological Survey. They analyzed the 2014 National Seismic Hazard Maps and the latest data on infrastructure and population from LandScan, a product of Oak Ridge National Laboratory.

The report focuses on the forty-eight contiguous states, where more than 143 million people are exposed to ground motions from earthquakes, but Leith noted that nearly half the U.S. population, or nearly 150 million Americans, are at risk of shaking from earthquakes when Alaska, Puerto Rico, and Hawaii are also considered.

In the highest hazard zones, where twenty-eight million Americans will experience strong shaking during their lifetime, key infrastructure could also experience a shaking intensity sufficient to cause moderate to extensive damage. The analysis identified more than 6,000 fire stations, more than 800 hospitals and nearly 20,000 public and private schools that may be exposed to strong ground motion from earthquakes.

Using the 2010 Census data and the 2012 replacement cost values for buildings, and using FEMA’s Hazus program, researchers calculated systematically the losses that could happen on any given year, ranging from no losses to a very high value of loss. However, the long-term average loss to the buildings in the contiguous U.S. is $4.5 billion per year, with most financial losses occurring in California, Oregon and Washington states.

“Earthquakes remain an important threat to our economy,” said Jaiswal. “While the west coast may carry the larger burden of potential losses and the greatest threat from the strongest shaking, this report shows that the threat from earthquakes is widespread.”