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|February 22, 2017|
Coastal earthquake fault more dangerous than thought
VENTURA – (INT) - A new study by a team of researchers, including one from the University of California, Riverside, as found that the fault under the city of Ventura would likely cause stronger shaking during an earthquake and more damage than previously suspected.
The Ventura-Pitas Point fault has been the focus of a lot of recent attention because it is thought to be capable of magnitude 8 earthquakes. It underlies the city of Ventura and runs offshore, and thus may be capable of generating tsunamis.
Since it was identified as an active and potentially dangerous fault in the late 1980s, there has been a controversy about its location and geometry underground, with two competing models.
Originally, researchers assumed the fault was planar and steeply dipping, like a sheet of plywood positioned against a house, to a depth of about 13 miles. But a more recent study suggested the fault had a “ramp-flat geometry,” with a flat section between two tilting sections, similar to a portion of a staircase.
In a recently published paper in Geophysical Research Letters, a team of researchers used computer modeling to test the two alternatives.
“Our models confirm that the Ventura-Pitas Point fault is a major fault, that lies flat under much of the coast between Ventura and Santa Barbara,” said Gareth Funning, an associate professor of geophysics at UC Riverside, one of the authors of the study. “This means that a potential source of large earthquakes is just a few miles beneath the ground in those cities. We would expect very strong shaking if one occurred.”
Future research will address the consequences of there being a fault ramp under Ventura. Researchers now can run more accurate simulations based on the ramp model to predict where the shaking will be strongest, and whether they would expect a tsunami.
Story Date: February 21, 2017