Guadeloupe seen as focal point for unreleased tectonic strain
FRISCO — The risk of a large earthquake and subsequent tsunami may be greater than previously thought, U.S. Geological Survey researchers say after studying the plate boundary in the Lesser Antilles region, where 20 of the 26 Caribbean islands are located.
The geologists estimate that enough unreleased strain may have accumulated offshore of Guadeloupe to potentially create a magnitude 8.0-8.4 earthquake. A magnitude 7.5 – 8.5 quake in 1843 killed several thousand people in Guadeloupe, and a similar quake in the future could cause several tens to several hundreds of fatalities, and hundreds of millions to billions of U.S. dollars in damages.
“Perception that a mega quake can occur in the Caribbean is low because none have been observed over the past century, and the rate at which the tectonic plates converge is fairly slow,” said USGS scientist Gavin Hayes, lead author of the paper. “Nevertheless, we show that enough unreleased strain may have accumulated on the subduction zone since the 19th century to generate a mega quake in the future.”
The impacted areas in Guadeloupe are of concern because these islands are popular with tourists.
The shaking hazard from the scenario earthquake is predominantly limited to Guadeloupe, though other islands could be affected by earthquake hazards from more local sources. Because of the thrusting style of the earthquake modeled, a tsunami could result, which would significantly impact Guadeloupe and would be hazardous in other areas around the Caribbean. The impact of the tsunami would likely be fairly minimal on the east coast of the U.S.
Based on historic strain release computations and previous research, the research team modeled several scenario earthquakes in the 7.5-8.5 magnitude range, using a variety of potential earthquake rupture areas and utilizing the USGS ShakeMap and PAGER software packages. Strong ground shaking during the scenario earthquake would likely cause loss of life and costly damages.
The paper was recently published in the Geophysical Journal International.