Two California coastal cities are at greater risk from tsunamis than previously thought, according to a study released Wednesday.
The study by the American Geophysical Union examined the flooding risk if earthquake faults in the Santa Barbara Channel area ruptured.
Coastal buildings directly opposite the faults would naturally be at risk. But a computer simulation of a magnitude-7.7 quake suggests the resulting wave would split, turn and move much farther inland than previously thought -- perhaps more than a mile.
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"The tsunami rotates and refracts -- turns and focuses on the Ventura-Oxnard area," said Kenny Ryan, of the University of California at Riverside and lead author. "That's a really interesting result that we didn't expect."
Ventura and Oxnard could be hit with a wave 23 feet high.
The tsunami might penetrate twice as far as the line stated in the official state tsunami plan -- which may need to be updated, Ryan said. Click here to view Ventura County's tsunami inundation map.
Earthquakes can generate tsunamis by displacing a large amount of water. A tsunami similar to the one simulated in the study might have occurred after the 1812 Santa Barbara earthquake -- a magnitude-7.0 quake likely caused by an offshore fault, according to researchers.
The event was considered a local tsunami, as opposed to a transoceanic tsunami caused by large earthquake in subduction zones, where a tectonic plate is pulled and pushed beneath another plate. Local tsunamis do not impact widespread areas, but they leave residents with only minutes to prepare because they occur closer to shore.