Hurricanes and typhoons could contribute to other natural disasters that occur long after the rain and winds subside. A new study led by University of Miami (UM) scientist Shimon Wdowinski finds a link between earthquakes and tropical storms, and shows that they may have actually initiated some major temblors, including the recent 2010 quakes in Haiti and Taiwan.
"Very wet rain events are the trigger," said Wdowinski, associate research professor at the UM Rosenstiel School of Marine and Atmospheric Science. "The heavy rain induces thousands of landslides and severe erosion, which removes ground material from the Earth's surface, releasing the stress load and encouraging movement along faults ... the reduced load (can) unclamp the faults, which can promote an earthquake."
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Wdowinski and a colleague from Florida International University analyzed data from major quakes in Taiwan and Haiti and found commonality between them, with a number of large earthquakes happening within the four years following a very wet tropical cyclone season.
Their research identified a handful of such instances from the past half-century: In Taiwan, the 2009 Morakot typhoon was followed by a magnitude 6.2 quake in 2009 and a 6.4 in 2010; Typhoon Herb in 1996 was followed by a 6.2 in 1998 and a 7.6 in 1999; 1969's Typhoon Flossie was followed by a 6.2 in 1972; the 2010 7.0 magnitude earthquake in Haiti devastated the nation just a year-and-a-half after two hurricanes and two tropical storms drenched the island nation in the span of less than a month.
According to the researchers, earthquakes are only likely to be triggered by tropical cyclones - including hurricanes and typhoons - along so-called inclined faults, where one side is above the other.
A similar study, published in 2009 in the journal Nature, found a link between typhoons in Taiwan and "slow quakes" - less violent temblors that release their built-up pressure over the course of hours or days instead of a few seconds.
Both studies are tied to the theory of hydroseismicity, first put forth in 1987, that suggests a link between localized variations in rainfall and seismic activity. Some supporters of the hypothesis have called for the deployment of more stream gauging stations to one day complement earthquake monitoring and forecasting.
The researchers from the University of Miami and Florida International University say they plan to analyze patterns in other regions that suffer from tropical cyclones and earthquakes, such as the Philippines and Japan.