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U.S. West Coast expecting major quake following Japan disaster

Wednesday, April 13, 2011 - 03:54

Apr 14 - Japan's devastating earthquake has raised concerns among geoscientists that the West Coast of the United States is likely to be next. From southern California to Alaska, the coastline shares its geography with the San Andreas fault and the Cascadia subduction zone, both of which scientists say, are primed for a major quake. Rob Muir reports.

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It has a population of about ten million people, but Los Angeles is built on shaky ground. It lies close to the San Andreas fault and geoscientists here worry that the fault is primed to rupture. The US Geological Survey is constantly studying stresses on the fault and creating simulations of what the next big quake might look like. The San Andreas is known as a "strike-slip" fault where the plates move horizontally. A magnitude 7.8 quake like this one wouldn't cause a tsunami, but the damage would be extensive. According to experts like UCLA's Jonathan Stewart a serious earthquake in the next 30 years is inevitable. (SOUNDBITE) (English) JONATHAN STEWART, PROFESSOR OF CIVIL ENGINEERING AT UCLA, SAYING: It is something we're very worried about. So no, we can't say it's going to happen next week, or next month but the probabilities are high". The last big quake to rock California struck at Northridge, near downtown Los Angeles in January, 1994. The quake killed more than sixty people. Engineers say the death toll would have been much higher were it not for stringent local building codes developed by the state after years of seismic activity. Even so, says Professor Stewart, the city is extremely vulnerable. SOUNDBITE (English): JONATHAN STEWART, PROFESSOR OF CIVIL ENGINEERING AT UCLA, SAYING: "For the tall buildings that we have, they will experience very extreme shaking. That earthquake could cut off our water supply for quite an extended period. The effects of it would be severe." There are similar concerns all the way up the coast to Seattle, Washington, where scientists have been sketching out cataclysmic earthquake scenarios for years. Civil engineering decisions are based largely on predictions about how severe an earthquake might be and what it might do to infra-structure like government buildings, roads and water supply. Seattle sits to the east of the Cascadia subduction zone, a plate boundary where tectonic movement takes place vertically. Iit is far more likely to produce a tsunami and for scientists like Dr. Eddie Bernard, the Japanese experience is providing valuable lessons. SOUNDBITE (English): NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA) SCIENTIST, DR. EDDIE BERNARD, SAYING: "The lesson learned may be if you have a subduction zone off your coastline, and you think the potential for that subduction area is a magnitude nine earthquake, then probably the preparation would be for a 40-meter run-up in certain areas." The conclusions of scientists like Eddie Bernard and his colleague Vasily Titov based on the Japanese data, will inevitably lead to difficult choices for city planners and politicians. Where to build and develop land, how high to build, how stringent the building codes, and how to create the best possible warning system are all questions that have to be addressd. SOUNDBITE (English): NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA) SCIENTIST, DR. VASILY TITOV, SAYING: "The Cascadia subduction zone is really due for a big event and what we saw in Japan is probably a good example of what we can see if a 9.0 earthquake happens here". It's been ten years since Washington State was shaken by its last significant earthquake, a magnitude 6.8 that caused damage but no deaths in the state capital Olympia. A much bigger quake is expected within the next fifty years and for residents all along the West coast, last month's catastrophe in northern Japan is a sobering reminder of their own vulnerability. Rob Muir, Reuters

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U.S. West Coast expecting major quake following Japan disaster

Wednesday, April 13, 2011 - 03:54