Oregon prepares for potential seismic doomsday

January 29, 2011 – PORTLAND – “One day this week, exactly 311 years after the Cascadia Fault’s most recent rupture, more than 37,000 Oregonians dove under desks and tables, or clung to sturdy walls, ducking and covering for 60 seconds. The exercise, the largest in state history, was a part of the first Great Oregon ShakeOut, an earthquake drill designed to prepare people for Cascadia’s next big move. While the drill lasted one minute, Rizzo said that if the Cascadia Fault ruptures, people are going to be hiding under tables a lot longer. “The actual shaking will be between five and 10 minutes long,” Rizzo said. That’s because Cascadia’s fault line — known as a subduction zone, an area where one tectonic plate is diving beneath another — is hundreds of miles long. “It takes between five and 10 minutes for it to break along the entire fault line,” Rizzo said. The geologist added that, in terms of sheer power, the Cascadia Fault has few rivals around the globe. “The amount of movement that takes place on the fault takes centuries to build up,” Atwater said. So when the fault does finally rupture, it unleashes hundreds of years of pent-up energy, producing a devastating earthquake. He said that on average, the Cascadia ruptures roughly every 500 years, but the intervals between quakes can be as brief as 200 years or longer than 1,000. Most recent data suggest there’s about a one-in-10 chance the Cascadia will rupture in the next 50 years. “One could happen here tomorrow, or it may take centuries for the next one to happen,” Atwater said. “But you want to be prepared for it when it does.” Rizzo said part of her job is to make sure people know about the risks and have emergency supplies and plans in place for an earthquake and ensuing tsunami. “We’ve got 9 million people in the impact zone between Washington and Oregon,” Rizzo said. To indicate the devastation a quake could cause, Rizzo pointed to Hurricane Katrina’s effect on New Orleans. “Just imagine New Orleans ― but from Northern California to British Columbia,” Rizzo said. “I don’t want to scare people. I want to empower them to take steps to make sure their families are safe.” –Our Amazing Planet