Scientists have discovered a mix of two disasters – hurricanes and earthquakes – and are calling it an "earthquake."
The bottom of the sea during hurricanes and noreasters may snore like a 3.5 magnitude earthquake and can last for days, according to a study published this week in the journal Geophysical Research Letters. Earthquakes are quite common, but have not been noticed before as they are considered background seismic noise.
An earthquake is more of a weirdness than a dangerous one because no one is standing on the sea floor during a hurricane, he said. Wenyuan fan, the Florida State University seismologist who led the study.
The combination of two scary natural phenomena can bring to mind “SharknadoBut earthquakes are different in two important ways: they are real and not dangerous.
"This is the last thing you need to worry about," said Fan.
Large storms cause giant waves in the sea, which in turn cause another type of wave. These secondary waves then interact with the seabed – but only in certain places – and that causes the shake, Fan explained. This only happens in places where there is a large continental shelf and a shallow flat seabed.
The research team detected 14,077 earthquakes between September 2006 and February 2015 in the Gulf of Mexico and the coasts of Florida, New England, Nova Scotia, Newfoundland, Labrador and British Columbia. A special type of military sensor is needed to detect them, Fan said.
Hurricane Ike in 2008 and Hurricane Irene in 2011 caused many earthquakes, according to the study.
Tremor is a type that creates a wave that seismologists don't normally look for when monitoring earthquakes. That explains why they have gone unnoticed so far, Fan said.
Ocean-generated seismic waves appear in the instruments of the US Geological Survey, "but in our earthquake-seeking mission, these waves are considered background noise," the seismologist said. Paul Earle from the USGS National Earthquake Information Center in Golden, Colorado.
The study makes sense, he said. Lucia Gualtieri, a Stanford University seismologist who was not involved in the work. It's interesting, she added, because it observes a frequency of waves that scientists haven't examined much.