Tsunami risk to Northern Calif assessed

Researchers in California say they've compiled the first study of the potential for destructive tsunamis on the northwest coast of the state. Using studies spanning the last three decades, scientists at the University of California, Santa Barbara, have compiled an evidence-based comprehensive study of the possibility of tsunamis in the region, the university said in a release Wednesday. The region has long been known to experience large earthquakes caused by seismic activity in the southern end of the Cascadia Subduction Zone, which stretches northward from the area of Mendocino, Calif. The researchers studied sedimentation patterns in salt marshes, floodplains and estuaries in the northwestern corner of California for signs of historic seismic events that could have led to tsunami activity. The study showed the region has experienced three major earthquakes over the last 2,000 years, and accompanying local sea-level changes at roughly 300- to 400-year intervals, with the last one occurring 500 to 600 years ago. "It's not a matter of if, but when," UCSB researcher Edward Keller said of the potential for the next major earthquake/tsunami event in the region. Such a great earthquake would impact not only the Northwest, but also send waves to Japan and Hawaii, the researchers said. The evidence, Keller said, should lead to far more foresight and planning along the impact areas in the region to avoid catastrophes on a level with the Japan earthquake of 2011 or the Indian Ocean quake of 2004.