Tsunami

To Southern Californians, it is a question that looms large: Could it happen here? The great 9.0 earthquake that struck Sumatra in December 2004 was the fourth-largest earthquake since 1900. The ensuing tsunami impacted coastal communities throughout the Indian Ocean and claimed more than 230,000 lives. Three Cal State Fullerton scientists—geological sciences faculty members David Bowman, Matthew Kirby and Brady Rhodes—convened in February to review the cause and impact of the earthquake and tsunami, and to discuss the possibility of a similar event happening in California.

David Bowman David Bowman, assistant professor of geological sciences, specializes in earthquake seismology and geodynamics, with an emphasis on earthquake prediction and fault interactions. Bowman is affiliated with both the Southern California Earthquake Center and the Institute of Earth Physics in Paris.

“Could it happen here?” Bowman asked. “We don’t have any faults in Southern California big enough to produce an earthquake like this. The San Andreas Fault can’t produce one. Northern California, Oregon and Washington have a similar fault—the Cascadia Subduction Zone—that perhaps could produce a similar quake.

“Can tsunamis happen here?” he asked. “It depends. An earthquake in Alaska once killed people in Crescent City, Calif. We can feel distant tsunamis. But the Channel Islands provide a natural barrier in Southern California that may provide a measure of protection against tsunamis from distant earthquakes. Although local tsunamis could be generated by either submarine landslides or earthquakes off the coast, these events are relatively rare and the size of the waves would probably be much smaller.”

• For more information, visit: http://geology.fullerton.edu/dbowman/index.html

Brady RhodesBrady Rhodes, associate professor of geological sciences, has spent the last 10 years conducting field research in Thailand regarding the tectonic evolution of Southeast Asia. Following the tsunami, Rhodes has been asked to serve as an adviser on a Thai project to reassess the earthquake and tsunami hazards of southern Thailand. He recently returned from Thailand, where he regularly travels each year to conduct research.

“When weird things begin happening at the beach, we need to get away from the ocean,” said Rhodes, indicating that this is the main lesson to be learned from the tragedy of the Sumatran tsunami. He has several amateur videotapes of people running toward the beach rather than away from it as the tsunami gained strength, ready to hit the shore with tons of water.

“You can walk away from it if you know what’s coming. In Khao Lak, Thailand, 2,500 tourists died in a low-rise hotel in a tourist area discovered by Scandinavians. They didn’t know what was coming.” When beaches empty of water in what appears to be an extremely low tide, a tsunami is indicated.

• For more information, visit: http://geology.fullerton.edu/brhodes/index.htm

Matthew KirbyMatthew Kirby, assistant professor of geological sciences, studies lake systems to infer past climate change. Kirby is also the department’s oceanography and environmental geology instructor.

“This tsunami had a global reach,” Kirby said, showing a diagram of waves hitting shores throughout the globe. “Somalia and Madagascar, on the other side of the Indian Ocean, were affected. Shocking diagrams show the travel time of the tsunami, whose devastation really can be thwarted. We can determine where and when they will hit. For example, over several hours different parts of Thailand were hit.

“But the devastation is preventable: Tsunamis always happen because of something else.”

• For more information, visit: http://geology.fullerton.edu/Mkirby/index.htm

 

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