Threat of major earthquake off California’s northern coast greater than previously thought

March 2014OREGON  – The Cascadia subduction zone is less known than the San Andreas fault, which scientists have long predicted will produce The Big One. But in recent years, scientists have come to believe that the Cascadia is far more dangerous than originally believed and have been giving the system more attention. The Cascadia begins at a geologically treacherous area where three tectonic plates are pushing against each other. The intersection has produced the two largest earthquakes in California in the last decade — Sunday’s 6.8 temblor off Eureka and a 7.2 quake off Crescent City in 2005. The area has produced six quakes of magnitude 7.0 or greater in the last 100 years, the California Geological Survey said. Officials in Northern California as well as Oregon and Washington are beginning to address the dangers. National Oceanic and Atmospheric Administration tsunami researchers are testing a new generation of tsunami detectors off the Oregon coast, which could provide earlier warnings about the incoming wave’s size. During the 2011 Japan tsunami, some of the first detailed alerts underestimated the size of the tsunami to be lower than the sea walls — and then communications were cut off. “So some people had a false sense of security,” said Vasily Titov, director of NOAA’s Center for Tsunami Research. “You want to have this information as accurate as possible.” Installing tsunami sensors on the deep ocean floor would provide better information on the tsunami’s size in as little as five minutes. It now takes about half an hour.
Titov said two underwater test sensors off the Oregon coast seemed to perform well in Sunday’s earthquake, though the quake did not produce a tsunami. In Grays Harbor County in Washington state, crews will begin building an elementary school gym this summer to double as a “vertical evacuation center” — built so that 1,000 people can flee to the roof during a tsunami, protected by a high wall. “We have no natural high ground,” said Ocosta School District Supt. Paula Akerlund. “So we have to evacuate vertically.” Washington state and federal officials have also been discussing building about 50 “tsunami safe havens,” such as artificial hills that could hold as many as 800 people. The 2011 Japan tsunami as well as other natural disasters like Hurricane Katrina have fueled efforts to better prepare for a major quake on the Cascadia fault. “Katrina was a worst case scenario for hurricanes in the gulf. And a Cascadia would be the worst case scenario for tsunamis on the West Coast,” said Paul Whitmore, director of the National Tsunami Warning Center in Alaska. For years, scientists believed the largest earthquake the area could produce was magnitude 7.5. But scientists now say the Cascadia was the site of a magnitude 9 earthquake more than 300 years ago. Ripping over a fault that stretches in the Pacific Ocean from the coast of Vancouver Island to Cape Mendocino, the quake on the evening of Jan. 26, 1700, was so powerful, entire sections of the Pacific coastline dropped by as much as 5 feet, allowing the ocean to rush in and leave behind dead trees by the shore. –LA Times
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This entry was posted in Black Swan Event, Dormant fault activation, Earth Changes, Earth Watch, Earthquake Omens?, High-risk potential hazard zone, Lithosphere collapse & fisssure, Potential Earthchange hotspot, Seismic tremors, Signs of Magnetic Field weakening, Tectonic plate movement, Time - Event Acceleration. Bookmark the permalink.

2 Responses to Threat of major earthquake off California’s northern coast greater than previously thought

  1. corwin99 says:

    Well this seems like the same old Cascadia story we have been hearing for 20-30 years, when it first started being “more serious than previously thought”. I think “previously thought means before 1980, not before last year. As before, we have no better idea than we did 30 years ago when such an earthquake might strike, although we have better equipment to determine the size of any tsunami it creates. I think announcements like this could get by with just the news about better sensors instead of adding in the 30 year repetition about how big it might be.

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  2. Diane says:

    We, on the West Coast, can always use a reminder about the devastation that could happen to us during our lifetime, so that we can prepare. But if we are so lucky as to not experience a major earthquake then it is still our duty as parents to pass this information onto the next generation. Remember the 2004 earthquake/tsunami in Sumatra, when 10 yr. old Tilly Smith warned her parents and they were able to clear the beach before the tsunami hit. Native folk lore in that area also protected the Langi village, immediately after the earthquake they headed for high ground. No one was killed, even though every last building in their village was swept off its foundation.

    I only know these details because I recently read the book: “Cascadia’s Fault — the deadly earthquake that will devastate North America.” I was so impressed by its information and dynamic presentation that I bought several copies to give to family and friends. (yes, I’m that person.) It is written by Jerry Thompson, and has a foreword by Simon Winchester.

    I have often wished I’d moved away (Vancouver Island, BC, Canada) but it’s such a lovely part of the world, and now I have family here, so I try to be that person that knows and prepares, just in case.

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