A new seismic phenomenon called stormquakes has been discovered as published in Geophysical Research Letters. These waves of energy which can radiate for miles into the continent are caused by the energy generated by large storms as they pummel through from ocean to continent. Wenyuan Fan and his team accidentally discovered the existence of stormquakes while they were developing methods to identify and study "low-frequency earthquakes." These differ from the earthquakes caused by the movement of tectonic plates. Low-frequency earthquakes have very low intensities, making them difficult for humans to pick up without a seismograph. This very sensitive device picks up vibrations from the earth's surface and records it in the form of waves. Not only are earthquakes recorded on a seismograph, but human activity has also triggered these devices to record the vibrations caused by celebrating fans jumping up and down inside a sports stadium and airplanes flying overhead. On the other hand, very low frequency earthquakes may be tough to record despite advances in seismographic technology, which became the focus of Fan and his team for further research.
The method Fan and his team had to put together signals from small regions to form a puzzle. While executing their procedure, they discovered a set of events that are quite similar to the earthquakes that Fan was looking for, with a slight difference. Upon checking events that occurred when these tremors hit, the team found out that they never occurred between May and August. This singles out the possibility of these new earthquakes being tectonic as they do not follow any season at all. Also, both coasts of the US have experienced these tremors, with the west coast experiencing more of them than the east coast. Upon further investigation, Fan and his team found out that these tremors coincide with large storms and hurricanes.
Not all storms can cause a stormquake, as evidenced by the lack of a stormquake when Hurricane Sandy hit the west coast back in 2012. The geology in which the storm hits is crucial to the generation of a stormquake. Fan explains that the area must have a broad continental shelf, a portion of the continent submerged in shallow water. This provides the storm enough time to generate wave energy, which can combine to form very low but long frequency waves.
While this research may seem entirely novel, the team hopes that it may be of use to understanding how the world works. According to Jonathan Berger from the Scripps Institute of Oceanography, as reported by National Geographic, low-frequency earthquakes won't be able to give a clearer signal of the inside of the planet, yet they may be able to fill in knowledge gaps on seismic activity in areas like New England.
