New Study May Help Scientists
Identify Regions at High Risk for Earthquakes
A groundbreaking study led by University of Miami (UM)
scientist Shimon Wdowinski shows that earthquakes, including the recent 2010
temblors in Haiti and Taiwan, may be triggered by tropical cyclones (hurricanes
and typhoons), according to a presentation of the findings at the 2011 AGU Fall
Meeting in San Francisco.
Wdowinski and a colleague from Florida International
University analyzed data from quakes magnitude-6 and above in Taiwan and Haiti
and found a strong temporal relationship between the two natural hazards, where
large earthquakes occurred within four years after a very wet tropical cyclone
During the last 50 years three very wet tropical
cyclone events -- Typhoons Morakot, Herb and Flossie -- were followed within
four years by major earthquakes in Taiwan's mountainous regions. The 2009 Morakot typhoon was
followed by a M-6.2 in 2009 and M-6.4 in 2010. The 1996 Typhoon Herb was
followed by M-6.2 in 1998 and M-7.6 in 1999 and the 1969 Typhoon Flossie was
followed by a M-6.2 in 1972.
The 2010 M-7 earthquake in Haiti occurred in the mountainous region one-and-a-half
years after two hurricanes and two tropical storms drenched the island nation
within 25 days. The researchers suggest that rain-induced landslides and excess
rain carries eroded material downstream. As a result the surface load above the
fault is lessened.
Fractures in Earth's bedrock from the movement of
tectonic plates, known as faults, build up stress as they attempt to slide past
each other, periodically releasing the stress in the form of an earthquake.
According to the scientists, this earthquake-triggering
mechanism is only viable on inclined faults, where the rupture by these faults
has a significant vertical movement.
Wdowinski also shows a trend in the tropical
cyclone-earthquake pattern exists in M-5 and above earthquakes. The researchers
plan to analyze patterns in other seismically active mountainous regions --
such as the Philippines and Japan -- that are subjected to tropical cyclones activity.
Marine Geology And
UM Rosenstiel School Of
Marine and Atmospheric Science
"Very wet rain events
are the trigger. 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 loads unclamp
the faults, which can promote an earthquake.”
of Miami Rosenstiel School of Marine & Atmospheric Science