3/25/14
On Wednesday, Del Norte and Humboldt Counties will participate in a test of the tsunami communications system. Tests of the Emergency Alert System happen all the time, so what’s different about this test and why is it important?
Five tsunamis have caused damage on the North Coast in the past 150 years. All were caused by earthquakes far away from us. The worst were in 1964 when a magnitude 9.2 earthquake struck Alaska and in 2011 by the magnitude 9 Japan earthquake. Both of these earthquakes sent their largest tsunami surges towards nearby coasts — the Kodiak Island and Prince William Sound region in 1964 and the Tohoku coast of Japan three years ago. But these earthquakes were so large and deformed such a large area of the sea floor that the wave energy sent outwards and away from the source region was still large enough to cause significant damage many thousands of miles away.
Residents of Alaska and Japan felt their respective earthquakes. The shaking lasted more than two minutes and no one slept through them. They received the natural warning loud and clear, and if they listened and took the right action, most had time to get to safety. Other areas of the Pacific, including Northern California, were too far away to feel the shaking. This is where the tsunami warning system comes into play.
Tsunami warning centers locate earthquakes anywhere that might pose a tsunami threat to U.S. coasts and territories. If it is large enough and located in an area where a damaging tsunami is possible, alerts are disseminated through the Emergency Alert System. It’s a complex system — each event has a unique code, and the codes used for tests and real warnings are different. The standard “test” messages don’t actually test all parts of the real alert system. The only way to make sure the warning messages will work when we really need them is to test the real “live” messages.
Past North Coast tsunami warning tests have paid dividends by revealing problems that were fixed afterwards.
In March of 2011, the system worked pretty well in distributing warnings of the tsunami coming from Japan. So why should we still test it? Systems and people change. We now have more sirens in North Coast communities. Humboldt County has updated its Reverse 911 calling system. In emergency management, systems must be tested repeatedly to make sure they work as intended.
There is a reason to be cautious about using the real warning codes because people may be confused and will respond as if a real tsunami is on the way. That’s where education and outreach come in. Everyone needs to be aware that Wednesday’s test is just that — a test, and not a real tsunami. Please let your friends and neighbors know about the test, especially if they are unlikely to have heard about the test.
What will happen on Wednesday? Between 11 a.m. and noon, your radio or TV program may be interrupted with a message about the test. National Oceanic and Atmospheric Administration weather radios with the alert feature will automatically broadcast the alert message. In some coastal areas of Humboldt and Del Norte counties, you might hear an announcement from an airplane (subject to weather conditions), receive a reverse 911 telephone message, or a siren being tested. Don’t be concerned if you don’t hear all of these different types of messages. The warning system is designed to be redundant and I hope everyone gets at least one notification. In Humboldt County, you don’t need to take any action, just note what you observed and go to the National Weather Service website at www.weather.gov/eureka or call 707-443-6484 to report how clear the message was and where you heard it.
Del Norte residents are being asked to participate in a full evacuation exercise during this test. If you live in the zone and the emergency alerts sound on the television, NOAA radio, public radio, tsunami siren or other means of notification, please walk out of the tsunami zone. Go on foot, you not to drive because this test is simulating a large earthquake and driving will most likely not be possible. There will be numerous personnel stationed along the evacuation routes to assist you with directions.
Whether or not you are participating in a drill this Wednesday, use this as an opportunity to discuss earthquake and tsunami safety with your family, friends, and co-workers.
Check out the Living on Shaky Ground website at www.humboldt.edu/shakyground or request a copy of the magazine from HSU’s Geology Department at 826-3691.
Lori Dengler is a professor in the Geology Department of Humboldt State University.
