At 10:17 a.m. on Oct. 17 more than 2,000 Jefferson county residents, including Port Townsend and Brinnon School District school students, members of neighborhood groups, local government employees, employees of Jefferson Healthcare, personnel at Naval Magazine Indian Island, and state ferry employees will join millions of participants across the state and the nation in practicing earthquake safety and preparedness as part of the International Great ShakeOut day.

“We’ll all hear the alarm,” said Shelly Leavens, the city’s director of communications and marketing, adding that city staff will practice the, “Drop, Cover and Hold on” earth quake drill. The events are made possible through a collaboration of several agencies including the United States Geological Survey, state Department of Natural Resources and Jefferson County Department of Emergency Management.    

Leavens said the annual event is a partnership that not only is good for earthquake preparedness, but critical for towns such as Port Townsend that lie within in a tsunami zone. Joining the Great Washington ShakeOut is part of the city’s multi-pronged effort “to educate the community about tsunami awareness.”

The Great ShakeOut earthquake drills are based on scenario earthquakes that could affect the area if they were to actually take place. It’s also an annual opportunity for people in homes, schools, and organizations to practice what to do during earthquakes, and to improve preparedness. 

Beyond Port Townsend, the main goal of the ShakeOut is to get Washingtonians prepared for major earthquakes and to learn what to do before, during, and after a quake event. The nationwide event began in 2009 with the idea that school-age children should be better trained as to what to do during this kind of emergency. Most schools agreed to the third Thursday in October and it has been held ever since.

When the alarm sounds on Thursday morning wherever a person is at that moment — at home, at work, at school, anywhere — they should “Drop, Cover, and Hold On” as if there were a major earthquake occurring, and stay in that position for at least 60 seconds.

Scientists say the Pacific Northwest is awaiting another giant earthquake like the more than 40 magnitude 8 and 9 events that have rocked the region in the last 10,000 years. This is due to the region’s proximity to the Cascadia Subduction Zone, a tectonic plate boundary where the oceanic Juan de Fuca plate is diving underneath the North American plate.

Scientists say the tension caused by friction between the two plates will eventually trigger an earthquake from northern California to southern British Columbia. Great Subduction Zone earthquakes are the largest earthquakes in the world, and the only source zones that can produce earthquakes greater than magnitude 8.5. The Cascadia Subduction Zone has produced magnitude 9.0 or greater earthquakes in the past, and scientists predict it will do so in the future.

The last known megathrust earthquake in the northwest was in January, 1700. Geological evidence indicates that such great earthquakes have occurred at least seven times in the last 3,500 years — a return interval of 400 to 600 years.

According to data from the Pacific Northwest Seismic Network, since Oct. 5, East Jefferson County has experienced three earthquakes of less than magnitude 1 along U.S. 101 just north of Old Gardiner Road.

On Sept. 30, a magnitude 1.2 quake shook an area just north of La Conner and just east of the Swinomish reservation. On Oct. 8, a 1.1 magnitude quake struck in the ocean, just south of San Juan and Lopez islands. Those are small enough that they don’t receive attention, aside from being recorded, but it’s good information for scientists to have.

The same database over the last two weeks shows scores of minor quakes along the I-5 corridor from Portland to Seattle, with recent seismic events also recorded at Mt. Adams, Mt. Rainier and Mt. Saint Helens.

The largest quakes recorded in the same two-week period in the Cascadia Subduction Zone occurred in the Pacific Ocean off the northern California coast and the southern Oregon Coast. Those quakes averaged between magnitudes 3 and 4.