FSU research: Strong storms generating earthquake-like seismic activity

Rodiano Bonacci
Ottobre 18, 2019

Assistant Professor Wenyuan Fan has coined the term "stormquakes" to describe a newly identified geological phenomenon where hurricanes or other strong storms trigger seismic events.

Researchers have discovered a new geophysical phenomenon where a hurricane or other strong storm can produce vibrations in the nearby ocean floor as strong as a magnitude 3.5 quake. "This involves coupling of the atmosphere-ocean and solid earth".

A stormquake is more an oddity than something that can hurt you, because no one is standing on the sea floor during a hurricane, said Wenyuan Fan, a Florida State University seismologist who was the study's lead author.

The study, which was published was published in the journal Geophysical Research Letters, notes that 14,077 stormquakes have been recorded between 2006 and 2015.

Researchers found a connection between strong storms and intense seismic activity - vibrations in Earth's crust - near the edge of continental shelves or ocean banks after they analysed almost a decade of seismic and oceanographic records from September 2006 to February 2019. "The exciting part is seismic sources caused by hurricanes can last from hours to days".

Specifically, researchers found evidence of more than 10,000 stormquakes from 2006 to 2019 offshore of New England, Florida and in the Gulf of Mexico in the United States, as well as offshore of Nova Scotia, Newfoundland and British Columbia in Canada. When the storm hit, several seismic events occurred off the coasts of Nova Scotia and New England.

The researchers said that hurricanes Ike and Irene triggered similar stormquakes, yet they found no seismic activity during Hurricane Sandy. In fact, they represent a new useful seismic source that scientists can use to investigate the planet's structure, especially in locations where we lack seismic instruments or earthquakes.

Fan, by piecing together the signals from smaller regions like a seismic puzzle, devised a method to track very-low-frequency earthquakes that are otherwise tough to trace over vast distances.

One example the researchers cited was Hurricane Bill, an Atlantic hurricane that originated on August 15, 2009, strengthened into a Category 4 hurricane and ultimately struck Newfoundland as a tropical storm.

Fan and his colleagues noted that not all hurricanes cause stormquakes. There are hotspots. Scientists detected no evidence of stormquakes off of Mexico or from New Jersey to Georgia in the United States.

The combination of two frightening natural phenomena might bring to mind "Sharknado", but stormquakes are real and not unsafe. These secondary waves then interact with the seafloor - but only in certain places - and that causes the shaking, Fan said. A special type of military sensor is needed to spot them, Fan said. "It really highlights the richness of the seismic wave field and suggests we are reaching a new level of understanding of seismic waves".

Altre relazioniGrafFiotech

Discuti questo articolo

Segui i nostri GIORNALE