Last year's Superstorm Sandy shook and pelted the northeast so violently its effects could be felt clear across the country, scientists said at a Seismological Society of America meeting in Salt Lake City Thursday.
Sandy, which caused more than $70 billion in damages, unleashed such a fury on the Earth through roaring waves that the vibrations in the Earth itself could be picked up by seismometers across the country. Scientists said the rumbles were equivalent to a magnitude-2 or magnitude-3 earthquake, although it's important to remember that earthquakes release their energy in a short burst, while storms are a far more sustained process.
"They are not earthquakes; they are seismic waves," says Keith Koper, director of the University of Utah Seismograph Stations. "Seismic waves can be created by a range of causes. ... We have beautiful seismic records of the meteor that hit Russia. That's not an earthquake, but it created ground motion."
While some of the movement was created by waves colliding with the continent, a majority of the energy came from waves colliding with other waves. This creates "standing waves," which can directly transfer energy to the seafloor by impacting it head-on.
"When Sandy made that turn to the northwest, although wind speeds didn't get dramatically bigger, the seismic energy that was created got tremendously bigger because the ocean's standing waves were larger from the wave-wave interaction," Koper explained.
Hurricane Sandy isn't the first storm to set off readings around the country. California scientists were able to remotely track Hurricane Katrina due to its impact on seismometers. Researchers are hoping to use data collected from events like Sandy and Katrina to image the Earth beneath us. This, in turn, will give scientists a more accurate understanding of how the rock reacts to disasters, natural or man-made.