New Evidence Shows Power of East Coast Earthquakes Virginia Earthquake Triggered Landslides at Great Distances

Earthquake shaking in the eastern United States can travel much farther and cause damage over larger areas than previously thought. U.S. Geological Survey scientists found that last year's magnitude 5.8 earthquake in Virginia triggered landslides at distances four times farther—and over an area 20 times larger—than previous research has shown. "We used landslides as an example and direct physical evidence to see how far-reaching shaking from east coast earthquakes could be," said Randall Jibson, USGS scientist and lead author of this study. "Not every earthquake will trigger landslides, but we can use landslide distributions to estimate characteristics of earthquake energy and how far regional ground shaking could occur." "Scientists are confirming with empirical data what more than 50 million people in the eastern U.S. experienced firsthand: this was one powerful earthquake," said USGS Director Marcia McNutt. "Calibrating the distance over which landslides occur may also help us reach back into the geologic record to look for evidence of past history of major earthquakes from the Virginia seismic zone." This study will help inform earthquake hazard and risk assessments as well as emergency preparedness, whether for landslides or other earthquake effects. This study also supports existing research showing that although earthquakes are less frequent in the East, their damaging effects can extend over a much larger area as compared to the western United States.

"The landslide distances from last year's Virginia earthquake are remarkable compared to historical landslides across the world and represent the largest distance limit ever recorded," said Edwin Harp, USGS scientist and co-author of this study. "There are limitations to our research, but the bottom line is that we now have a better understanding of the power of East Coast earthquakes and potential damage scenarios." The difference between seismic shaking in the East versus the West is due in part to the geologic structure and rock properties that allow seismic waves to travel farther without weakening.