5 ms·

I like to think about how I'd react in the 15 minutes I have between the earthquake and tsunami. How tall would this tsunami be? Quick googling shows the talle

by someear 11y ago

I like to think about how I'd react in the 15 minutes I have between the earthquake and tsunami. How tall would this tsunami be? Quick googling shows the tallest one ever is 524 meters. Assuming the tsunami is that tall, going into tall buildings might not work - tallest building in Seattle, Columbia Tower, is 287 meters (+50m in elevation increase), and is a few blocks from the waterfront . Best bet is to run/bike up the hill to Capitol Hill, which is 100m higher in elevation, and about 2 miles inland (and east of the I5). Just need some science to figure out how far the wave will go given these hill angles and elevations in Seattle to find a precise safe spot (assuming the tallest tsunami ever, and assuming all other variables like me being able to react instantly and fallen buildings not blocking my path stay constant, which they of course won't).

cossatot 11y ago
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 http://geology.com/records/biggest-tsunami.shtml [2]: https://www.youtube.com/watch?v=n2AGlhuCQ-A https://www.youtube.com/watch?v=n2AGlhuCQ-A
- idlewords 11y ago
  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.
rconti 11y ago
If you DID go up into a tall building, what's your plan? Jump into the water just as the building's collapsing?
- Flammy 11y ago
  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.
falcolas 11y ago
Don't forget the elevation change from the subducted plate falling back down. Personally, I'd look for a motorcycle and head for the hills.
chrisfosterelli 11y ago
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?
- ihsw 11y ago
  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.
- protomyth 11y ago
  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.
  - pavedwalden 11y ago
    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.
eCa 11y ago
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/tsunamis-and-seiches http://www.seattle.gov/emergency-management/what-if/hazards/...
ecdavis 11y ago
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.
scarmig 11y ago
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.

by someear 11y ago

cossatot 11y ago

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

idlewords 11y ago
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.

rconti 11y ago

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

Flammy 11y ago
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.

falcolas 11y ago

Don't forget the elevation change from the subducted plate falling back down. Personally, I'd look for a motorcycle and head for the hills.

chrisfosterelli 11y ago

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?

ihsw 11y ago
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.
protomyth 11y ago
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.
- pavedwalden 11y ago
  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.

eCa 11y ago

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/tsunamis-and-seiches http://www.seattle.gov/emergency-management/what-if/hazards/...

ecdavis 11y ago

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.

scarmig 11y ago

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.