Earthquakes: Preparing for the Big One in Lewis County


Editor’s Note: This is Part One of a two-part series that will continue Tuesday with a look at potential impacts to Lewis County dams in an earthquake. 

Between the devastating April 25 earthquake in Nepal and the fact that it has been 14 years since the 6.8 magnitude Nisqually Earthquake shook the region, preparedness is on some people’s minds — including local and state officials.

Lewis County Emergency Management Director Steve Mansfield said the next “big one” could happen at any time.

“They are, fortunately, very infrequent, but the longer the time goes that you don’t have one, the more severe they usually are,” Mansfield said.

To protect against fatalities, injuries and damage, Mansfield said a statewide four-day earthquake scenario is being planned for next summer. What areas of the state will be most damaged in the scenario are still being determined. Even if Lewis County is not one of the areas, it would still have a role to play by providing aid to other areas in the state.

In the meantime, various county departments work to provide structural and preparedness mitigation against earthquakes.

Representatives from jurisdictions throughout the county are working to provide county officials with updated information regarding all possible hazards, including earthquakes, for an update to the Lewis County Multi-Jurisdictional Hazard Mitigation Plan, which was last revised in 2010.

In the current version of the plan, the entire county is identified as being at risk for damages from an earthquake. 

The county’s geographic information system department uses Federal Emergency Management Agency’s loss-estimation model called HAZUS to determine the extent of damage based on various scenarios. 

GIS Manager Matt Hyatt said when the county ran the program for the Hazard Mitigation Plan, it used a 7.0 magnitude earthquake with a 60 kilometer depth and an epicenter near Salkum. 

Essentially, county officials used a scenario similar to the Nisqually Earthquake, but moved it to central Lewis County.

“Our thinking was that it seems not too uncommon, that size quake, that type of quake, and then by moving it to Lewis County we get a sense of what would it be like if it happened here,” Hyatt said.

Countywide, a total of 2,314 buildings — agricultural, residential, commercial, government, educational, religious and industrial — would receive moderate to complete damage based on the model. 

In looking at each building, Mansfield said the officials have to consider what is in the building — people and objects — and what services the building provides.

“When something like this occurs on a large scale, the things that we look at, in this order, are life safety, incident stabilization and then protection of property,” Mansfield said.


Twenty-two buildings classified as “other residential” would be completely destroyed by the earthquake in the scenario. A total of 46 households would be displaced and 33 people would need short-term shelter.

The 2010 Hazard Mitigation Plan also notes that building in areas subject to earthquakes will occur, however new infrastructure is required to be constructed according to the International Building Code for earthquakes, wind and snow loads.

The majority of Lewis County is classified as a D1 in the Seismic Design Category, which means buildings are located in areas expected to experience severe ground shaking, but aren’t located near a major fault. 

While new structures are built to code, Doyle Sanford, building official with the county, said if an older building is undergoing a remodel involving more than 50 percent of the value of the structure, it has to be brought up to current code.

If there is no way to bring a historical building up to code without losing its historical look, and the building is on the National Register of Historic Places, then it gets a pass.

Sanford mentioned in 2011 the Evaline School near Winlock underwent a seismic retrofit while still keeping the appeal of the old school.

Safety is a priority for schools not only because of the number of children and adults who utilize the buildings, but also because if a shelter is needed, schools and churches usually have the most room in emergencies, Sanford said.

Along with buildings codes, the type of soil that is being built on also matters as rock or granite soil makes for a sturdier foundation.

While there are structural ways to mitigate against damage, Mansfield said preparedness and safety also help protect citizens.

In schools, students learn “Drop, Cover and Hold On.” He said parents should work on plans with their children and any other dependants at home.

Plans for continuity of operations for the home and work should be in place and practiced.

There are preventative measures residents can take as well, such as ensuring heavy hanging items are properly mounted on walls at home and at work. In the event of an earthquake, people need to use common sense and stay away from areas where things could fall on them.

For earthquakes or any type of hazard, Mansfield said residents should have enough food, water, medications and other necessities to last for three to five days.

“Don’t live in fear,” Mansfield said. “… It’s a matter of doing some practical things that you can do to help mitigate your financial situation, your shelter situation, your food and clothing situation should something happen.”