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Strong hurricanes can produce “stormquakes” offshore, new study finds

Analysis of a decade of records shows hurricanes causing seismic activity on continental shelf

Florida has repeatedly seen the power of a major hurricane — winds that can blast a building apart like a bomb, waves that push 20 feet inland and obliterate anything in their path.

But now a Florida State University professor says the strongest hurricanes are so powerful they can churn up something like an earthquake out on the continental shelf.

By analyzing a decade of records of seismic and oceanographic activity, Wenyuan Fan, an assistant professor of earth, ocean and atmospheric science, and his colleagues found that the most powerful storms can transfer energy into the ocean as strong ocean waves, and the waves interact with the solid earth producing intense seismic source activity.

He’s calling them “stormquakes.”

“It was actually discovered by accident” Fan said in an interview Wednesday. He and his colleagues wrote an algorithm looking for one thing, and as a result stumbled across this, he said: “We realized there was a correlation between this and extreme storm events.”

The “stormquakes” could cause seismic activity that’s the equivalent of a 3.5 magnitude earthquake, they found. The data they analyzed showed more than 10,000 such “stormquakes” from 2006 to 2019 offshore of New England, and Florida, as well as elsewhere in the Gulf of Mexico, and off the coast of Nova Scotia, Newfoundland and British Columbia in Canada.

For instance, they found that Hurricane Irene, which hit North Carolina as a Category 1 storm, caused stormquakes near Little Bahama Bank while it was still a Category 3 off of Florida.

RELATED: Hurricane Michael retroactively upgraded to Category 5.

Fan said that Hurricane Michael, a Category 5 storm that flattened everything in its path when it hit the Panhandle last year, probably did too.

RELATED: Before and after pictures of Hurricane Michael damage.

“Given the seafloor topography in the Gulf, I would expect Hurricane Michael to have generated stormquakes offshore,” he said. However, he said, “it’s hard to validate the hypothesis” because the equipment used for their detection has now been moved to another area.

The peer-reviewed study was just published in the scientific journal Geophysical Research Letters.

Not all powerful hurricanes cause such earthquake-like activity, the researchers found. For instance, Hurricane Sandy, which made landfall as a Category 3, spawned nothing detectable, they found.

The people who are squarely in a storm’s path probably don’t feel the quakes it causes, Fan said. The seismic activity takes place too far offshore for be detectible by anyone onshore. But in places where there are offshore facilities — for instance, the hundreds of oil and gas wells in the Gulf of Mexico — the study’s findings could be important, he said.

The research on the ramifications of the phenomenon “is really just beginning,” Fan said. It shows, he said, “how little we know” about our own planet and how its weather works.