Fortunately, the tallest tsunami was from a rockfall in a fjord[1], not from a subduction zone earthquake. They are typically ~10 m, and it's really the wavelength, not the amplitude, that is a problem because there is so much water that the inundation is more like a flash flood than a quick slap from a breaking wave.

Second, I don't believe tsunamis from subduction zone earthquakes on the Cascadia trench will impact Seattle that much, because (as you may be able to see from your location) the Olympic peninsula is in between you and the trench. The wave coming through the Strait of Juan de Fuca will spread outward into Puget Sound and mostly dissipate against Camano and Whidbey Islands.

The big tsunami hazard for Seattle itself is the from an earthquake on the Seattle fault[2].

[1]: http://geology.com/records/biggest-tsunami.shtml [2]: https://www.youtube.com/watch?v=n2AGlhuCQ-A

There's a seiche hazard in Seattle, though. Lake Washington will slosh back and forth in resonance with the shaking. Basically every natural feature in the Pacific Northwest has some exotic way of killing you.

IANAS[1], but I believe one of the reasons why the Lituya Bay tsunami was so big was simply that the water had nowhere to go but up. In a more lowlandy situation the water would spread over much larger areas at a lower elevation. Also, considering Seattle's geographic position (away from the Pacific) I would be surprised if any big tsunami would hit Seattle directly.

A little bit of Googling found this[2]. The largest known tsunami to hit Seattle was 16ft, 1100 years ago.

That said, heading for the hills is probably a good choice anyway.

[1] Seismologist

[2] http://www.seattle.gov/emergency-management/what-if/hazards/...

Out of curiosity, I looked up estimates of what I would guess might have been the largest tsunami in recent history--the one associated with the KT event 65 million years ago. And, yes, it created tsunamis much larger than we've ever seen.

To put it in perspective, it seems like a 10km asteroid would cause a 1.5km tsunami along the nearby coasts if it crashed in the middle of the (contemporary) Gulf of Mexico; a 200m tsunami if it crashed in the middle of the Indian Ocean; and a 100m tsunami if it crashed in the middle of the Pacific.[0]

Some coastal areas would experience this more than others because of geological formations, naturally, even holding distance from the impact site constant.

[0] I'm not sure how much this depends on angle of impact, speed of impact, and composition, if it does at all.

I wish I could find some definitive resources on whether or not a building would be considered safe in a tsunami, and if it would be better to go for higher floors or lower floors.

I imagine that after such a large earth quake, many buildings would be unstable and potentially open to collapse from the force of a tsunami. I'm sure going to higher ground would be a better idea if possible, but say if it was iffy to get there in 10 minutes, should I spend that time looking for a high building instead or just get as far inland as possible?

Remembering a lot of the video from Japan, it looked like most of videos were from people who went into parking garages (concrete)[1]. Regular buildings took a pretty big hit, but I'm not sure how the local building code / materials played in that.

1) I'm going with the logic that surviving video person uploading to youtube is probably a good sample of the "worked" side of the equation.

I suppose parking garages would let a lot of the water flow through the open sides, whereas a regular building would receive a lot of force against the exterior walls.

Probably, and they are designed for a higher weight load than a regular building.

That's really interesting. I guess when the 'big one' hits, those of us in my Sacramento apartment complex can go hang out next door with our cars in the garage. I wouldn't have thought of that myself honestly.

In addition to the risk of total collapse, there's also the risk that the remaining floors would be impassable.

Debris (furniture, broken walls, etc) can be a dangerous obstacle, especially when you have to traverse several/dozens of flights of stairs, much of which will be wet, muddy/dirty, and possible destroyed in some places. This danger magnifies when you have to evacuate large amounts of people of varying mobility (young, old, sick, or otherwise infirm).

Entrances and exits will be serious obstacles if not outright impassable, due to large amounts of debris and unknown/unstable physical integrity.

Tsunami evacuation and safety policies are outlined for movement and monitoring large groups of people, not just individuals.

With regards of where you should go -- go outside and move to higher ground.

From the article:

> A grown man is knocked over by ankle-deep water moving at 6.7 miles an hour. The tsunami will be moving more than twice that fast when it arrives. Its height will vary with the contours of the coast, from twenty feet to more than a hundred feet.

That's on the coast, not in the sound, of course.

If you DID go up into a tall building, what's your plan? Jump into the water just as the building's collapsing?

Remember any tsunami is going to be 20 min to an hour after the earthquake. If the building is still standing when the water arrives, it probably isn't coming down.