Seismometers Picked Up Hurricane Melissa’s Historic Power Like an Earthquake

Hurricane Melissa was so strong it shook the Earth hundreds of miles away

By Robin George Andrews edited by Andrea Thompson

Hurricane Melissa will go down as one of the worst hurricanes ever recorded in the Atlantic Ocean, reaching a strength that only a handful of storms have achieved in history. Melissa was so powerful — with peak winds of a staggering 185 miles per hour — that she literally shook the ground hundreds of miles away in Florida, where her march across the ocean was captured by seismometers, instruments designed to detect earthquakes.

Although many intense storms have already been detected by these sensors, the recordings highlight the destructive force of Melissa, a Category 5 hurricane that devastated parts of Jamaica, Cuba and the Bahamas. They also highlight how a tool typically used for geological purposes can improve our understanding of one of Earth’s fiercest weather phenomena, including providing a window into hurricanes that raged before satellite and aircraft reconnaissance were possible.

Although seismic waves are easily associated with fault movements and shaking, “seismometers aren’t just used for earthquakes,” says seismologist and earthquake geologist Wendy Bohon, whose organizational affiliation cannot currently be given due to the ongoing federal government shutdown. “Seismometers detect anything that puts energy into the ground. It could be Taylor Swift concerts, it could be construction, it could be people walking around the seismometers.” Landslides, avalanches, asteroid impacts, volcanic eruptions and clandestine nuclear weapons explosions all appear as curious squiggles in the tools’ results because they all generate seismic waves.

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Hurricanes and typhoons are no exception and they shake the earth’s crust in two different ways. The first is “due to wind vibrating trees, telegraph poles, fence posts, etc., which then propagate through the ground as a seismic wave,” explains Stephen Hicks, a seismologist at University College London.

The second, more important component comes from storms that churn up the ocean itself. “As the waves rise and fall, they drum on the ocean floor,” Bohon explains. Sometimes this percussive action is represented on seismometers by subtle peaks and troughs. Hurricane Melissa was recorded ominously on Jamaica’s seismometers as jagged teeth eerily evident in the days before landfall. “It makes your heart tighten a little bit because you recognize the ferocity of the storm,” Bohon says.

Hurricanes and typhoons are tracked and studied relatively easily in real time: barometers and daring “Hurricane Hunter” pilots record changes in atmospheric pressure, ocean sensors monitor temperature changes, and satellites can construct three-dimensional images of these maelstroms. Seismometers, which operate continuously and are found all over the world, can also be used to track the path of the hurricane, says Andreas Fichtner, a seismologist at the Swiss Federal Institute of Technology in Zurich.

While useful in the here and now, this is particularly useful for understanding hurricanes in the somewhat earlier past, when aerial surveys and satellite searches were not options. “In the pre-satellite era, we already had a seismic network on the Earth’s surface,” says Fichtner. It’s not as dense as today, but it’s still enough for hurricane researchers who hope to go back in time to discover where tropical cyclones originated and storms broke up before.

This multidecadal seismic soundtrack also shows its potential for determining the intensity of past hurricanes. Seismic waves generated by storms effectively record changes in ocean wave heights. That means scientists could calibrate the cacophony of current hurricanes based on their intensity, then use what’s preserved in old seismic catalogs to see if cyclones have gotten stronger over time.

As sea surface temperatures have risen dramatically with global warming, climate models predict that in coming years hurricanes will become stronger, bringing higher wind speeds, heavier precipitation, and more vigorous storm surges that will hit anyone in their path. There is some evidence that this effect is already at work. And if, as recent research suggests, seismometers can determine the strength of tropical storms that existed long ago, our understanding of this trend will undoubtedly improve.

The fact that seismometers can be used in unconventional ways to study our rapidly changing world is fascinating, says Bohon. But seeing increasingly wild storms like Melissa appear on these sensors is also “scary and heartbreaking,” she adds.

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