The U.S. Geological Survey scientists are reporting that last year's Virginia earthquake was felt over an area 20 times larger than previous research suggested.
It is estimated that approximately one-third of the U.S. population could have felt the August 2011 earthquake centered in Mineral, Va., making it one of the largest earthquakes in the last 100 years. Shaking reports came all the way from southeastern Canada to Florida, and as far west as Texas.
"The reason the motion traveled farther is that the rocks here are much older and denser, and less fractured, and if you go out in the western U.S., they're younger and more fractured," says Virginia Tech engineer Russell Green, who presented a paper on the quake at last week's U.S. Geological Society of America conference.
Green and other scientists are using this new information to update their previous assumptions about the impact of east coast seismic events, and improve models for safety in building codes and practices.
"The Virginia earthquake certainly is going to add tremendously to that effort, because now instead of having to use more theoretical models to try to make the prediction we have empirical data," says Green. "And so the way they were trying to develop these relationships before was using low-level empirical models and trying to use a more theoretical approach for higher levels. And a magnitude 5.8 is the largest earthquake we've had in the eastern U.S. in the last hundred years or so."
This new data shows earthquakes of this magnitude in the central and eastern U.S. can produce landslides in areas 20 times larger than previous worldwide studies indicated.
Last year's 5.8 magnitude earthquake centered in Louisa County caused an estimated $200 million in damage.