Researchers discover 'stormquakes', earthquake-like seismic activity generated by storms

In a new discovery, researchers have found what they have termed 'stormquakes' described as new geophysical phenomenon where a hurricane or any other strong storm can produce vibrations in the nearby ocean floor as strong as a magnitude 3.5 earthquake.

"We're calling them 'stormquakes,'" said lead author Wenyuan Fan, an assistant professor of Earth, Ocean and Atmospheric Science at Florida State University.

"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," Fan added.

The findings were published in the journal Geophysical Research Letters.

Researchers found a connection between strong storms and intense seismic activity - vibrations in Earth's crust - near the edge of continental shelves or ocean banks after they analysed nearly a decade of seismic and oceanographic records from September 2006 to February 2019.

Specifically, they found evidence of more than 10,000 stormquakes occurring from 2006 to 2019 offshore of New England, Florida and 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. The exciting part is seismic sources caused by hurricanes can last from hours to days," Fan explained.

In order to detect and locate seismic events and determine if they qualify as 'stormquakes', researchers developed a new method.

They found 2009's Hurricane Bill, which made landfall on Newfoundland on August 22, produced numerous stormquakes off the coasts of New England and Nova Scotia.

Similarly, Hurricane Ike in 2008 caused stormquake activity in the Gulf of Mexico and Hurricane Irene in 2011 did the same near Little Bahama Bank off the coast of Florida.

Not all hurricanes cause stormquakes, but when they do, the stormquakes seem to be concentrated in certain hotspots, according to the study's authors.

Stormquakes are strongly influenced by the local oceanographic features and seafloor topography, Fan said.

"We weren't even aware of the existence of the natural phenomenon. It really highlights the richness of the seismic wavefield and suggests we are reaching a new level of understanding of seismic waves," he said.