Serious waves off the US West Coast

[Seaweed Doc]

As the sergeant on Hill Street Blues used to say, "Let's be careful out there."

Giant, 40-foot waves smash West Coast, people warned to stay away

 

[drrich2]

The article you linked includes this blurb - "The director of the University of Georgia’s Atmospheric Sciences program, Marshall Shepherd, told Live Science that the huge waves were caused by a low-pressure system centered in the Gulf of Alaska, and that while the waves can grow to dozens of feet high, they fortunately don’t travel inland like tsunami waves."

I wonder why not? Is it down to being smaller than tsunami waves, or is there some other dynamic at work?

Richard.

 

[Jay]

I wonder why not? Is it down to being smaller than tsunami waves, or is there some other dynamic at work?

because: (top is a regular wave, bottom tsunami)

 

[SnohomishDiver]

I think Jay described it nicely. Weather related waves are at the surface - with the depth of the wave below an "average" surface being about equal to the wave crest.

Tsunamis form when a huge amount of water is dispaced at depth due to tectonic forces or a massive submarine landslide. That water has to go somewhere, so it moves outward in all directions - those waves can propagate for thousands of miles. At sea, in deep water, an average person on a boat wouldn't even notice one going by - it's only when the tsunami starts to feel bottom in shallower water that it starts to stack up.

 

[Seaweed Doc]

I'd have said the tsunami has a longer period. The wavelength is really long. As it years shore, the wavelength decreases so the wave builds height. But the period is still the same. The wave huts and keeps coming for give or take 5 minutes, not just a few seconds.