Seattle homes are more at risk than most people understand. We forget about the lurking risk of a large earthquake because we don't get reminded with tremors frequently. Did you know this region had a 9.0 earthquake in the year 1700? It will happen again, its just a matter of time! Some of us were around in 2001 and remember being shaken by the Nisqually Earthquake, a 6.8M quake. Each unit of magnitude on the Richter scale is 32x more powerful than the last. That means a 9.0 quake would be over 1000x more powerful!
Compounding the risk is that most houses in Seattle are built before codes required seismic resistance. Houses built before 1980 have no anchor bolts and their shear capabilities are seriously inadequate.
Earthquake retrofitting is an easy and relatively low-cost way to protect your greatest assets. You can't put a price on life; the price to repair your home could be $100k+, if not a total loss. Repairing after a serious earthquake will be a nightmare because the demand for this service could leave you waiting for a very long time, all the while - you cant live in your house because it is unsafe.