Hurricane Andrew hit Category 5 as it approached Cuba and Florida in August 1992.
Credit: NASA
PORTLAND, OREGON: Hurricanes can be detected on seismometers, says an expert, who claims that we may be able to extend the historic North Atlantic hurricane record using seismic noise records.
When people think about a seismic record, they think about an earthquake record, but there is also background vibrational "noise" that's always there, said Carl Ebeling, a geophysicist at Northwestern University. "It doesn't matter where you're standing on the globe; you can see it everywhere. It's very pervasive."
"We've always been interested in the earthquakes, but there's a lot that can be learned just by listening to the noise," said Ebeling, who suggested the technique last week at the Geological Society of America's annual meeting held in Portland, Oregon.
Filling gaps in the data
By analysing this noise from digital seismic monitoring stations, Ebeling has been looking for hurricanes that were missed using other methods or took place before detailed records began in the 1940s. He has found patterns that corresponded with well-known hurricane periods.
Preliminary results from studying seismic data taken during Hurricane Andrew in 1992, indicated spikes in microseismic power - faint tremors caused by natural phenomena such as waves - which corresponded with the low barometric pressure and high wind speeds associated with hurricanes.
"Seismologists and climatologists tend to do their own things, but combining these methods seems to work," said Ebeling. "The results of this research have the potential for impacts reaching far beyond the seismological community."
Wave action
When most people think of seismometers, they think of the analogue versions with their old-fashioned needles, bobbing up and down on a paper roll recorder, he said.
But new digital seismometers use electronic sensors, amplifiers, and recording devices so that information can automatically be uploaded to a computer. "A number of North Atlantic hurricanes have occurred since the digital recording era began, allowing a depth of analysis not possible with analogue records" said Ebeling.
What researchers are seeing is atmospheric energy coupled into the water column and, ultimately, the ocean floor to produce waves which show up on seismic records.
