Powerful Storms May Be Causing Offshore ‘Stormquakes’

Hurricane Bill was seen tracking northwest from Puerto Rico, all the way to Newfoundland. This was back in august of this year, 2019. As the hurricane passed offshore of New England, it was noticed that the winds churned up the ocean. As a result, it ended up interacting with the seafloor. The result were stormquakes. It should be noted that if the hurricanes are powerful enough, they can whip the ocean into a frenzy. This can then create wave energy that is so strong to the point that it hammers the seafloor. This has the potential to produce a novel kind of quake.

On the 14 of october, some geological research letter mentioned that these stormquakes were actually a newly identified type of interaction that happens between the earth’s atmosphere, the crust, as well as the ocean. It was also noted that unlike in the case of earthquakes that were created when the subsurface shifted within the earth, what drove the seismic signals are actually the waves of the ocean that would have been whipped into deep swells, either by a hurricane or nor’easter. Results have shown that stormquakes can be as powerful as a magnitude 3.5 earthquake. Of course, this cannot be noticed by people, but they can be detected by seismometers.

At the moment, scientists are doing all that they can in order to get the first start at understanding just a little bit more about this part of the seismic record, which is little-studied at the moment. For quite a long time, scientists have known that all the constant sloshing of the waves of the ocean produces seismic signals. These siesmic signals were created at frequencies of about once every few minutes. This phenomenon is known as the “earth’s hum”. It is also known that ocean waves will produce some high-frequency signals that are called microseisms. These ones occur about every 5 seconds or so. However, in between the seismic noise, you will be able to find another band of signals. These are generated in the ocean and they are known to occur once every 20 to 50 seconds or so. Also, they appear at a frequency of between 0.02 and 0.05 hertz. At the moment, it seems that scientists do not really know or understand what produces the seismic signals.

Scientists have actually tried to figure out what could possibly be the triggers of these signals that seem to come from within the earth. What they did is that they analyzed some seismic data that was collected from 2006 to 2015. This seismic data was picked up from a network of moveable seismometers that marched across the country from the west, all the way to the east. They were part of the USArray. The scientists made sure that they started by focusing on the data that was collected from the Pacific Northwest. It was then that they found out what they thought were previously undetected offshore earthquakes that were occuring in that mysterious seismic band. However, it was found out that they were seasonal, of which earthquakes do are not seasonal.

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