[Island Chris]

Hi Jim, while half of that 6" is global rise (maybe 2/3), at locked subduction zones some areas warp up and some warp down while locked, and then the motion reverses during the quake itself. Can be up to several meters in a quake (1964 Alaska) in areas where there is no long term vertical motion. If 2 m in 400 years, is 5 mm/yr, higher than even the current global rise. But, Seattle is inland from the likely locked part of fault, so subduction related vertical motions should be slower. The answer to ground vertical motion is likely known.

Chris