Post by KNOWTHIS on May 9, 2005 0:26:19 GMT -5
Tsunami danger real, but remote, study says
By Kimm Groshong , Staff Writer
PASADENA -- Southern California faces a real tsunami threat from offshore earthquakes and submarine landslides, scientists said Friday at a meeting of the Earthquake Research Affiliates at Caltech.
Conceding that "it's a low probability event for Southern California," Mark Legg, a geologist and president of Legg Geophysical in Huntington Beach, said the consequences of such a tsunami would be high given the number of people who live along the coast and the costly infrastructure and port operations that could be damaged.
Jose Borrero from USC's Tsunami Research Center said California's tsunami hazard must be readdressed given the state's extensive offshore faults, steep underwater slopes and deep troughs.
He cited a July 1998 earthquake of magnitude less than 7.0 that scientists believe triggered an underwater landslide, which in turn produced a tsunami that killed about 2,000 people in Papua New Guinea. Some scientists believe a similar event could hit Southern California, for example, off the Palos Verdes peninsula.
Borrero and his colleagues from the Tsunami Research Center have produced maps showing the areas that would be affected by various potential tsunamis. In the absolute worst-case scenario, he said, a Southern California tsunami might reach heights of 30 to 40 feet in places.
Last month, Borrero and other USC researchers published a study that said a tsunami off Palos Verdes could inundate Terminal Island and affect the ports of Los Angeles and Long Beach, with run-up on Orange County beach cities. The study, published in Civil Engineering magazine, said the damage could cost as much as $42 billion.
The center's simulation of a 7.6-magnitude earthquake on a fault underlying the Channel Islands can be viewed at www.usc.edu/dept/ tsunamis/california.
Earthquakes, landslides, volcanic activity and meteorite or asteroid impacts can all set off tsunamis by displacing large volumes of water in the ocean.
The Cascadia subduction zone -- which has been compared to the zone where the Dec. 26 magnitude 9.0 earthquake struck and produced the Sumatran tsunami -- lies off the west coast of Oregon and Washington. Although the region is hundreds of miles away, Legg said, "we don't really know what the effects of a Cascadia tsunami will be in Southern California."
Tom Heaton, a Caltech professor of seismology and civil engineering, said scientists also don't know what would happen to high rise buildings in Seattle, Portland and Vancouver if a great earthquake strikes along the Cascadia subduction zone. Because scientists have no record of equivalent ground shaking and what it means for tall buildings in metropolitan areas, scientists are working to extrapolate data to such a potential event.
Jim Goltz, from the state's Office of Emergency Services, said although a tsunami is extremely unlikely to reach as far inland as Pasadena, inland areas could be called upon to send emergency responders to affected coastal communities. Los Angeles County has developed a tsunami task force following the Dec. 26 disaster.
By Kimm Groshong , Staff Writer
PASADENA -- Southern California faces a real tsunami threat from offshore earthquakes and submarine landslides, scientists said Friday at a meeting of the Earthquake Research Affiliates at Caltech.
Conceding that "it's a low probability event for Southern California," Mark Legg, a geologist and president of Legg Geophysical in Huntington Beach, said the consequences of such a tsunami would be high given the number of people who live along the coast and the costly infrastructure and port operations that could be damaged.
Jose Borrero from USC's Tsunami Research Center said California's tsunami hazard must be readdressed given the state's extensive offshore faults, steep underwater slopes and deep troughs.
He cited a July 1998 earthquake of magnitude less than 7.0 that scientists believe triggered an underwater landslide, which in turn produced a tsunami that killed about 2,000 people in Papua New Guinea. Some scientists believe a similar event could hit Southern California, for example, off the Palos Verdes peninsula.
Borrero and his colleagues from the Tsunami Research Center have produced maps showing the areas that would be affected by various potential tsunamis. In the absolute worst-case scenario, he said, a Southern California tsunami might reach heights of 30 to 40 feet in places.
Last month, Borrero and other USC researchers published a study that said a tsunami off Palos Verdes could inundate Terminal Island and affect the ports of Los Angeles and Long Beach, with run-up on Orange County beach cities. The study, published in Civil Engineering magazine, said the damage could cost as much as $42 billion.
The center's simulation of a 7.6-magnitude earthquake on a fault underlying the Channel Islands can be viewed at www.usc.edu/dept/ tsunamis/california.
Earthquakes, landslides, volcanic activity and meteorite or asteroid impacts can all set off tsunamis by displacing large volumes of water in the ocean.
The Cascadia subduction zone -- which has been compared to the zone where the Dec. 26 magnitude 9.0 earthquake struck and produced the Sumatran tsunami -- lies off the west coast of Oregon and Washington. Although the region is hundreds of miles away, Legg said, "we don't really know what the effects of a Cascadia tsunami will be in Southern California."
Tom Heaton, a Caltech professor of seismology and civil engineering, said scientists also don't know what would happen to high rise buildings in Seattle, Portland and Vancouver if a great earthquake strikes along the Cascadia subduction zone. Because scientists have no record of equivalent ground shaking and what it means for tall buildings in metropolitan areas, scientists are working to extrapolate data to such a potential event.
Jim Goltz, from the state's Office of Emergency Services, said although a tsunami is extremely unlikely to reach as far inland as Pasadena, inland areas could be called upon to send emergency responders to affected coastal communities. Los Angeles County has developed a tsunami task force following the Dec. 26 disaster.