Scientists Discover a Wild New Seismic Phenomenon Called ‘Stormquakes’
Storms that form over the water like hurricanes and nor'easters can actually shake the seafloor, according to PBS, and scientists are calling this phenomena "stormquakes." The discovery was published in the scientific journal Geophysical Research Letters.
According to National Geographic, they can rumble for thousands of miles and hop continents. Large storms were believed to trigger movement in coastlines, but this new study has traced them to the source.
Researchers were looking for something entirely different – low-frequency earthquakes, not at all like the Michael Bay-level devastation we imagine – when they noticed aberrations in the data. A certain set of wavelengths happened only between the months of September and April, and could be found on the East coast just as often as they were on the West. (Typical earthquakes in the United States, by contrast, don't care what time of year it is and are much more common out west where the fault lines are active.) Then someone made the connection that these frequencies occurred at the same time as certain devastating storms and hurricanes.
Storms that develop offshore churn up gigantic ocean waves, and some of these waves actually ripple into each other with enough strength to impact the seafloor. These quakes can last for days with the intensity of a 3.5-magnitude earthquake. It doesn't happen everywhere – thank goodness – just where you have a wide, flat stretch of continental shelf (or the edge of a continent in the Earth's crust) beneath the sea. Several stormquakes each were caused by Hurricanes Ike and Irene in 2008 and 2011. Conversely, Hurricane Sandy's devastation didn't even register a blip on the seismometer.
Believe it or not, this chthonic-sounding phenomenon isn't dangerous. "This is the last thing you need to worry about," said Wenyuan Fan, a seismologist and the study's lead author. Stormquakes have, apparently, been happening for a very long time – we just never noticed them.
Stormquakes' seismic waves show up on our instruments all the time, they just don't match what we're looking for when we're scanning for "regular" earthquakes. In fact, they'd previously been "considered background noise" according to Paul Earle, a U.S. Geological Survey seismologist.