Here’s some recent news from my geologist buddy Marco.
The plate displacement during the recent Japan quake was roughly 27 metres, of which 7 metres were vertical movement, so the starter wave was already that high. The wave made it more than 10 miles inland in places. A wave traveling through deep water will not change its wavelength while its traveling, but only once it hits the shallows. The travel time is quite extreme, pretty well 1000 kph, or slightly less, so in the case of the Cascadia fault, the wave would arrive only 5 minutes later on the West Coast of Vancouver island. The Japanese fault is pretty close to the same distance the Cascadia Fault lays from Vancouver Island. Kind of sobering if you think about around the campfire on Vargas Island in the Clayoquot.