Stormquakes: Powerful Storms Discovered That Generate Earthquake-Like Seismic Activity
A Florida State University researcher has uncovered a new geophysical phenomenon where a hurricane or other strong storm can spark seismic events in the nearby ocean as strong as a 3.5 magnitude earthquake.
“We’re calling them ‘stormquakes,’” said lead author Wenyuan Fan, an assistant professor of Earth, Ocean and Atmospheric Science. “This involves coupling of the atmosphere-ocean and solid earth. During a storm season, hurricanes or nor’easters transfer energy into the ocean as strong ocean waves, and the waves interact with the solid earth producing intense seismic source activity.”
The research is published in the journal Geophysical Research Letters.
Fan and his colleagues analyzed nearly a decade of seismic and oceanographic records from September 2006 to February 2019 and found a connection between strong storms and intense seismic activity near the edge of continental shelves or ocean banks.
Specifically, researchers found evidence of more than 10,000 stormquakes from 2006 to 2019 offshore of New England, Florida and in the Gulf of Mexico in the United States, as well as offshore of Nova Scotia, Newfoundland and British Columbia in Canada.
“We can have seismic sources in the ocean just like earthquakes within the crust,” Fan said. “The exciting part is seismic sources caused by hurricanes can last from hours to days.”
Fan and his colleagues developed a novel approach to detect and locate seismic events and determine whether the seismic event is a stormquake. It must occur during a stormy day and meet other geophysical standards to determine the robustness of the correlation between the storm and the seismic event. Additionally, other seismic events such as earthquakes must be ruled out.
One example the researchers cited was Hurricane Bill, an Atlantic hurricane that originated on Aug. 15, 2009, strengthened into a Category 4 hurricane and ultimately struck Newfoundland as a tropical storm. It was a Category 1 hurricane when it approached offshore New England on Aug. 22, 2009.
When the hurricane arrived, numerous seismic events were located off the New England and Nova Scotia coasts, which produced transcontinental surface waves.