Cascadia Earthquake Preparedness: A New Tool for the Really Big Earthquake

Big earthquakes in Central Oregon and much of the Pacific Northwest are pretty rare. However, geologic history has shown that the Cascadia earthquake, aka “the Really Big One” has occurred about every 300 to 380 years. Since the last one occurred on January 26, 1700 (322 years ago) we know Oregonians need to be prepared. This is a scary disaster, but most people will be able to survive. If you are aware and prepared at least a little more than you are now, you can become more resilient to recover and rebuild more quickly.

The Oregon and Northern California coast will experience the most severe shaking as well as a very large tsunami that can extend north to Washington and British Columbia. All of Oregon will experience shaking that lasts about 5 to 7 minutes. There will be secondary disasters such as landslides, liquefaction (silty soil near waterways acts like beach sand), and possible flooding. This will result in lengthy power outages, blocked or damaged roadways, bridges, and utility disruptions.

In Central Oregon, officials are helping neighborhoods and communities prepare now. While stick-built houses should sway through the initial earthquake and aftershocks, unreinforced masonry buildings may not hold up as well. In both types of homes, windows could break and wall hangings could fall, both could result in injuries.

Power could be out for an extended amount of time as Bonneville Power Administration and other power sources check for possible damage. Officials will want to inspect and make sure power lines are safe to re-energize, too. All types of supplies including food, fuel and anything on regular delivery route – the supply chain – will need to wait for roads to be cleared or repaired. Even then, supplies will need to come from other regions for quite a while. It is a priority to get roads reopened. Many bridges on Highway 97 have already been seismically upgraded.

Building inspectors and engineers along with police, fire, medical, and public works personnel have developed mutual aid agreements to deploy to the heavily impacted areas to the west. FEMA has identified the Redmond area as a location to stage supplies needed in the recovery of the hard-hit areas of the coast and the western valleys. These activities will result in impacts to our local community. Local residents should try to be able to shelter-in-place and “be your own first responder” for at least two weeks, and up to four weeks. If that is not possible, try to get 24 to 48 hours of food and water on hand. Then, watch or listen for announcements from your local emergency manager for directions to additional supplies or shelter.