Like Nepal, and unlike California, we live in a tectonic plate crumple zone. Here are 3 maps that zoom into our neighborhood, showing the risks. At a broad level, California and Oregon are shoving us into Canada:
That crumple action means you can expect one of 3 types of earthquakes here. The most frequent and least serious type are like the 2001 Nisqually quake- deep underground with movement that will knock over brick chimneys, topple TV’s, and maybe collapse aging viaducts or a building in Pioneer Square. The second type is a magnitude 9 mega quake that will happen when the Cascadia Subduction Zone off the coast moves, similar to what happened in Japan. If that goes you will feel very long lasting and powerful waves from side to side, with most of the danger being to older, taller structures, plus tsunami flood zones along the coast. Finally, the most dangerous type of quake here in Seattle is a shallow quake nearby, most obviously along the Seattle Fault, with violent shaking leveling older buildings in large numbers:
The Seattle Fault most catastrophically ruptured in AD 900, causing West Seattle to rise up by 20 feet relative to Wallingford and triggering tsunamis in Puget Sound. Regardless of the type of quake, Wallingford is fairly lucky compared to other parts of Seattle. We are not in a slide zone and are not on top of an old lake bed that is likely to liquify during the quake, so we won’t suffer from the worst amplified shaking:
In theory our earthquake communication hubs are Lower Woodland Park, the Good Shepherd Center, and History House down in Fremont. I expect my communications hub will be my back yard plus a transistor radio, or if things get really ugly then the satellite radio in my car, and my camping gear will help with the rest.
The building boom in Seattle has its blessings, because prior to 1980 there were no earthquake building codes in Seattle at all, and it wasn’t until 1992 that the Seattle Fault was discovered. As we watch 45th and Stone Way get plowed under, it’s worth being thankful that those old single story brick buildings are being torn down before being subjected to a major earthquake.
My understanding is that our public schools are up to code except for Lincoln, which is slated for a rebuild in 2019, but many private schools are not up to code as there’s no system forcing upgrades like there are in public schools. We went on a tour of a fancy private school and were surprised that nobody even knew if their charming 100 year old brick building had been retrofit. Even the real estate agents I speak with say that earthquake readiness doesn’t register with buyers, much less renters.
In general, retrofits are a lot less effective than new construction. Retrofits bolt houses to foundations and roofs to houses, but they typically don’t insert shear walls and other stuff that happens in new construction. So if you live in a charming old bungalow you may wish to befriend the Amazon employee in the modern McMansion next door so that they will let you in after the big one hits and it’s 40 degrees and raining outside.
Here’s standard preparedness things to be aware of:
- Make sure everyone who stays in the house alone knows how to turn off mains for gas, electricity, and water
- Attach stuff to walls so it doesn’t topple
- Have first aid supplies and a fire extinguisher at the ready
- Retrofit your home if it hasn’t been done already
- Be ready for a week of being unsupported by society- no groceries, no fresh water, no medical care, no electricity or communications
Nearly one million people have been killed by earthquakes since 2000. Here is the list of quakes that have killed at least 20,000 people in the last 15 years:
|5/12/2008||Eastern Sichuan, China||87,587||7.9|
Finally, I want to pimp a book that’s probably the best read I’ve had in the last 5 years. It’s a detailed account by the Seattle Times science reporter on how northwest geologists figured out our earthquake risks here. Here it is: