California Doesn't Even Have To Fall Into The Ocean To Get In Trouble

March 28, 2004 10:10 PM

California's Tsunami Risk. " In the open ocean, tsunami waves travel at speeds of up to 600 miles per hour... As the waves enter shallow water, they may rise rapidly. Typical peak wave heights from large tsunamis in the Pacific Ocean over the last 80 years have been between 21 and 45 feet at the shoreline... If a large earthquake displaces the sea floor near the coast, the first waves may reach the shore minutes after the ground stops shaking. There is no time for authorities to issue a warning." 40 years ago this weekend the Alaskan Prince William Sound earthquake and its ensuing tsunami killed over 120 people -- 12 as far South as California. Nothing compared to the thousands hit in the 1998 Papua New Guinea tsunami disaster, but still it's worth keeping an eye on California's tsunami risks. Or the entire West Coast's activity.
posted by namespan (20 comments total)

"... I went down down down, and the waves got higher... and it churned churned churned... the ring of fire...the ring of fire..."

Have a great day, fellow West Coasters!
posted by namespan at 10:14 PM on March 28, 2004

Took this picture while in Oregon recently. Being from the East Coast I found it odd enough to document. Climb little man, climb!
posted by stbalbach at 10:32 PM on March 28, 2004

Oh no.. East Coast Tsunami Risk
posted by stbalbach at 10:37 PM on March 28, 2004

Those Tsunami signs are all along the open coast in Washington as well. In BC, along the open coast there isn't much population and there's also no notice that I've ever seen about the tsunami danger. I think I've only seen one sign about the rogue waves that hit the beach. I've often thought it'd be a good idea to at least warn tourists about those.

When I visited an Indian reserve north of Tofino one year, I talked to a woman who was there as a girl during the 1964 wave. No one warned them at all, they had no clue. One minute, she said, they were in the house up from the beach, the next minute they were still in the house on the beach. And that was a small inlet just inside the open coastline, the wave continued to build all the way down the sound until it hit Port Alberni.
posted by Salmonberry at 11:15 PM on March 28, 2004

WE'RE ALL GOING TO DIE! It's every man for himself! AAAAAUGHHH
posted by kevspace at 11:27 PM on March 28, 2004

I took a course in Natural Disasters at college in New Orleans, and one of the best and most disturbing moments was when the professor said "If Montserrat changes into a more explosive volcano, the tsunami would hit the Gulf Coast within a few hours. The mayor would hop on a helicopter, and there would be no warnings to evacuate. There wouldn't be time."

Woo!
posted by Katemonkey at 11:43 PM on March 28, 2004

hm.

I was going to link the old "Back and forth... Back and forth... TSUNAMI!!!" Calvin and Hobbes strip, but apparently the database has been taken down...
posted by kaibutsu at 11:53 PM on March 28, 2004

This paper puts a damper on some postulated tsunami events that might otherwise have been fascinating to see on the telly. (Warning: May hurt eyes)
posted by biffa at 6:19 AM on March 29, 2004

here's a good link describing the tsunami damage in chile from the 1960 earthquake (the largest on record, i believe). i had a better link that showed more of the chilean damage, but can't find it now (and it was probably in spanish).

i go running out along the beach here in la serena and i know that if there's a big quake i need to try heading for high ground (unfortunately i think the typical delay is 20min, and at for much of the route i'm more than 20min running from high enough ground. maybe the adrenalin will help...). luckily, my apartment is on a hill. all the hotels, cabins and appartments along the seafront are going to be toast, though (the town itself is on higher ground away from the sea to avoid shelling from the english pirates/national heroes :o)
posted by andrew cooke at 6:47 AM on March 29, 2004

And we'll sink with Kalifornja, as it falls into the seeeeeeeeeeeeeeeeeeaaaaaaaaaaaa....
posted by Ufez Jones at 7:40 AM on March 29, 2004

....leaving the cool serenity of Arizona Bay.
posted by keswick at 8:32 AM on March 29, 2004

Anybody know how clear a forming tsunami would be from the shore? I spend a lot of time out on the rocky shore, walking far out into the ocean on the rocks and I've often wondered: If I were looking at the ocean and a tsunami were to form, how much time would I have to run back to my car and drive away fast? Would it simply be a matter of seconds?
posted by crazy finger at 8:34 AM on March 29, 2004

If I were bicycling on Long Beach, I'd pedal over to this baby, and ride inland in style.
posted by Faze at 10:02 AM on March 29, 2004

Depends on how tall you are, how tall the wave is and how fast the water's moving.

This link talks about how to caculate distance to the horizon and at what distance you can see something over the horizon.

So, if you're 6' tall, the distance to the horizon is 2.86 nautical miles (3.30 statute miles, if you are so inclined). Apparently, these things dont start to get tall until they get into shallow water. (speed and height of the wave are both related to the depth of the water). Generally speaking, they seem to be limited to about 100' tall (although there are notable exceptions). So, horizon distance would be 11.69 / 13.46 miles. Total distance would then be 14.55 / 16.76 miles. How much time that gives you depends on how fast it's going, and I can't seem to dig up anything that talks about their speed when coming ashore. A wave travelling at 600 mph (the value above) would cover that distance in about 100 seconds or so, but everyone agrees they slow down as they approach the shore.

So, the answer seems to be "prolly not much time to run, but it's not clear how much time".

ps - apparently, these things also come in many flavors, i.e. not just the massive wave of lore. So, it might be tough to see one coming. Which makes the problem that much tougher for crazy finger.
posted by Irontom at 10:16 AM on March 29, 2004

crazy finger: this photo, from andrew cooke's link, above, should give you a sense of how fast a 600mph wave moves.
posted by scarabic at 10:16 AM on March 29, 2004

ah shit, let's try that again
posted by scarabic at 10:17 AM on March 29, 2004

hey scarabic - how about some more exposition? What's the story behind that pic?
posted by Irontom at 12:05 PM on March 29, 2004

I seem to remember in a PBS show about tsunamis, that a big sign is the tide goes waaaaay out. Which makes sense. If a big wave is about to hit the beach, usually the surf pulls back a little farther.

So, if you see the tide going out much farther than it should, RUN! RUN FOR YOUR LIFE! Or don't. Cause you likely won't have enough time to get your car started, much less away.
posted by Salmonberry at 12:56 PM on March 29, 2004

Screw it. I'm paddling outside and bombing that sonofabitch.

If I'm going to die, I might as well die skipping like a rock down the face of the largest wave ever ridden, making that "Wooo-hoooo-hooooooo!" noise Goofy makes when he goes skiing. If I'm really lucky, I'll even get tubed and it'll echo loud enough for people to hear it on land.

I've seen it go from a burly (but mild) 6 foot swell to a 15-20 foot distant-hurricane generated storm swell in less than one set. (Waves come in sets with a lull in between each set. The number of waves in a set varies from day to day, but stays pretty consistent from hour to hour.)

It's pretty freaky to be far outside the breakers already just waiting for your average 6 footer, and then you notice everyone around you suddenly paddling "outside" like their life depends on it (it does). Then you turn around and all you see is a scary looking black wall coming in from the storm swell, and start paddling like mad yourself.

A smooth, rolling, shallow-breaking 20 footer on a point with a nice offshore breeze is one thing, though. A tsunami is an entirely different thing. As I understand it, you're not going to notice the tsunami until it's right up on you. It's not the same type of wind-driven surface oscillation. Chances are it won't even form the same sort of peak a wind-driven swell would, as it's more of a very rapid tidal surge than a true standing wave. If it forms a face at all, it'll be a rough, sloppy one.

I'd still try to ride it if I was already in the water, though, but the chances of this are pretty slim, and the chances of surviving are even slimmer.

I do know one thing: Charlie don't surf!
posted by loquacious at 6:57 PM on March 29, 2004

This ocean, it... oh, never mind.
posted by weston at 3:18 PM on March 30, 2004