A test of the Pacific County All Hazard Alert Broadcast outdoor sirens are expected to sound Thursday as part of the Great Washington ShakeOut.
The shake out is a worldwide earthquake drill in which people are asked to drop, cover and hold for at least 60 seconds. The drill is scheduled for Thursday, Oct. 17 at 10:17 a.m.
As part of the drill, Pacific County Emergency Management Agency will test the three minute-tsunami siren. Before and after the siren there will be a verbal message sent out as well. National Oceanic and Atmospheric Administration weather radios set to receive the monthly test will also activate during the Great ShakeOut.
The Emergency Management Agency will send out a countywide reverse 911 message on Wednesday, Oct. 16 to warn folks about the siren activation, said Scott McDougall, director of the county emergency management agency.
About 3,178 people in Pacific County are registered to participate in the drill, according to the emergency management agency. Many of those participating are from schools, government offices and businesses. Roads and some services may be briefly disrupted.
When the real siren sounds
The Washington State Department of Natural Resources published new maps on Oct. 10 that show the fastest routes to safety for Port Townsend, Ilwaco, Long Beach and Seaview, and Westport.
These maps, produced by the Washington Geological Survey, show the on foot evacuation times from areas that would be hit by a tsunami caused by a Cascadia subduction zone earthquake.
It would take about an hour for someone to evacuate to high ground if they walked at a slow pace of 2.46 mph from Long Beach City Hall, 115 Bolstad Ave. W, according to the new maps.
In Seaview, it would take about 30 minutes for someone walking the same pace to evacuate from the Depot Restaurant, 1208 38th Place.
These maps plan for the worst-case scenario and are based on a once in 2,500 year event, McDougall said. The more likely scenario would probably plan for different wave heights, he said. But Japan planned for the most likely scenario ahead of the 2011 earthquake off the Pacific coast of Tohoku, and the worst-case scenario happened, McDougall said.
People shouldn’t be discouraged by their chances of survival if they see they are in a place with an hour long evacuation time, McDougall said.
“Every step inland and every step up increases the chance of survival,” McDougall said.
The most recent Cascadia subduction zone quake happened about 319 years ago. The zone is an offshore area where the Juan de Fuca tectonic plate is pulled under the larger North American plate, according to a news release from the Department of Natural Resources. This subduction zone produces megathrust quakes about every 300 to 600 years.
These maps are modeled on a magnitude 9 Cascadia earthquake. The onshore and offshore geologic records show the last big earthquake happened in 1700 creating a tsunami that hit all of the Pacific Northwest and traveled across the ocean to Japan.
By using models for larger Cascadia events, the maps provide a scenario that is useful for smaller events as well, according to the news release.
Considerable uncertainty remains regarding local conditions after a Cascadia event. The entire land surface is expected to drop six feet or more during a powerful offshore quake, with this shaking resulting in broken street pavement, downed utility poles and liquefaction of water-saturated soils. This means it is crucial for everyone living and working near sea level to know the quickest footpaths to higher ground, as travel by motor vehicles is likely to be impossible.
Walking evacuation routes are not yet available for Ocean Park and the north end of the Peninsula. There are also not yet maps for Chinook and the surrounding towns. The Department of Natural Resources did not provide a timeline for when those maps would be available.