Just buy a smaller house in the east bay. It's got to be cheaper than your bigger house.
+1. This big discontinuities in retirement are a lot to handle, and on the not unlikely chance that you are not pleased by the new circumstances, you are essentially out of luck unless you have way more money than you need.
Regarding tectonic movements in the NE pacific, these were not even understood or even suspected when I came up here. Everything west of I-5 toast? In the ~60 years I've lived on the west coast, all but 50 have been lived west of I-5. Other than now, when I live on one of the hills east of I-5 and a 15 minute walk away, a grand total of 2 years were spent E of I-5.
It sounds like whenever this happens, many cities and towns in the NW will be destroyed, and one wonders if they could recover. Around 1970 I met a guy who had experienced the 9.2
quake near Anchorage in 1964. He was strongly impressed! The most disruptive quakes I have personally experienced were the 6.5 San Fernando Valley quake of 1971 and the Nisqually quake (6.8) of 2001. People were moving from LA as soon as they could get trucks for a considerable time after that. It also coincided with an aerospace recession. And, a 6.5 is a whole different fish from a 9.
Personally, although Seattle suits me to a tee, if one of my son's family and life were not here, I might try to talk girlfriend into decamping. Where to? Maybe Spokane, maybe Reno or Las Vegas, maybe Missoula or Billings. The other plan, let fate decide. One of my favorite writers is the late Walker Percy from Covington, LA. Using southern Louisiana hurricanes he shows that the effects of huge public disasters are not always negative for those who are caught in them, even if they perish. But even if I managed to get her to leave with me, then I to some extent become responsible for her happiness, which might be a bit much.
Ha