As all port cities along the West Coast, Seattle will find the sloshing Pacific washing it into pieces. Buildings constructed with only gravity and earthquakes in mind do not withstand being covered by a flood tide, something the engineers did not think of. Foundations erode, and water soaked walls crumble, so that the weak link theory applies and they crash, one by one, often into each other. All cities should be avoided during the shift, due to these types of problems. Mount St. Helens will activate, violently, during the shift, and spew for some decades afterwards, so living downwind from this volcano will find any survivors struggling against constant dust. Thus, moving to what is now north, toward Canada, or clinging to the coast line which will afford good fishing, is the best option for Aftertime living.
Note Puget Sound commentary.