Catastrophic tsunami possible on West Coast

[Tormod]

The type of devastating tsunami that struck the southern coast of Asia is entirely possible in the Pacific Northwest of the United States, but might not cause as much loss of life there because of better warning systems, according to experts at Oregon State University.

 

OSU is home to the Tsunami Wave Basin at the Hinsdale Wave Research Laboratory, one of the world's leading research facilities to study tsunamis and understand their behavior, catastrophic effects and possible ways to reduce the destruction they can cause. As the death tolls rises into the tens of thousands in Asia and the number of homeless above one million, OSU experts say many of the same forces that caused this disaster are at work elsewhere on the Pacific Ocean "ring of fire," one of the most active tectonic and volcanic regions of the world.

 

This clearly includes the West Coast of the U.S. and particularly the Pacific Northwest, which sits near the Cascadia Subduction Zone. Experts believe, in fact, that it was a subduction zone earthquake of magnitude 9 – almost identical in power to the sub-sea earthquake that struck Asia on Monday – that caused a massive tsunami around the year 1700 that caused damage as far away as Japan. And the great Alaska earthquake in 1964 caused waves that swept down the Northwest coast, causing deaths in Oregon and northern California.

 

"The loss of human lives from this latest tsunami is staggering," said Harry Yeh, an internationally recognized tsunami expert and the Edwards Professor of ocean engineering at OSU. "We have to ask, 'why?' Clearly, they didn't have the same kinds of warning systems that we have on the West Coast of the U.S. That is why the research that we do here is so important. As tragic as the event is, it also represents a learning opportunity and we have a responsibility to learn from it what we can.

 

"We didn't learn what we could have from the Alaska event," Yeh added, "because we didn't have the instrumentation we have today, and we didn't have the knowledge base. The tsunami event this weekend also happened during the daytime, so there are a lot of pictures and video of the devastation, which will help the research effort. Most of the other recent major events happened at night."

 

Robert Yeats, professor emeritus of geosciences at OSU, agrees that the reason for the great loss of life in Sri Lanka, India, and other Asian countries was the lack of a tsunami warning system.

 

"That much loss of life wouldn't happen here for either a local or distant tsunami because of warning systems operated by the National Oceanic and Atmospheric Administration, with laboratories in Newport and Seattle," Yeats said. "NOAA would record the earthquake on seismographs and issue bulletins about the progress of a tsunami. Deep-ocean buoys off the Aleutian Islands and Cascadia would also record the passage of tsunami waves in the open ocean."

 

For a tsunami caused by a Cascadia earthquake, people on the coast would have about 15 minutes to get to high ground, Yeats said. Emergency managers of coastal counties have told residents about planning escape routes from a tsunami, and schools in Seaside, Ore. have had tsunami evacuation drills. Some coastal communities also give warnings through a siren for those vacationers who aren't keeping up with the news. Visitors to the coast should look for the blue and white tsunami warning signs on Highway 101 and some beach areas.

 

Research on tsunamis is being greatly enhanced by the new Tsunami Wave Basin at OSU, a $4.8 million facility with advanced technology built with the support of the National Science Foundation. It allows scientists from anywhere in the world to conduct experiments and monitor results. It also helps them learn about how tsunamis behave in different types of ocean terrain and what effects they might have once they reach land, said Dan Cox, an associate professor of engineering who directs the facility.

 

"The underlying goal of all we are doing is to ultimately reduce the loss of lives," Cox said. "We've had a number of scientists from Japan and throughout the United States checking in with us already, and we expect more from around the world.

 

"We're not working alone," Cox added. "Much of our work is in collaboration with NOAA's Pacific Marine Environmental Laboratory, and the support of the National Science Foundation has been critical. They've funded the construction of the facility during the past four years, and will support the operation and maintenance of it for the next 10 years."

 

Is it possible that a tsunami will strike the U.S. during that time? Experts are not sure.

 

"In the Pacific Northwest, there is no way to tell whether the next Cascadia earthquake will strike tomorrow or 100 years from now," Yeats said. "We must prepare for the worst case scenario, both in tsunami escape preparations and in not building in potential tsunami inundation zones."

 

One of Yeats' colleagues is Chris Goldfinger, who has spent years studying the Cascadia subduction zone. Goldfinger says that in the last 10,000 years, there have been 19 major earthquakes in the zone that runs from northern California to Vancouver Island.

 

"There are only a few places in the world with a pattern long enough that we can study," he said, "and one of them is Cascadia. We cannot accurately predict earthquakes, so we have to look to the past for patterns."

 

Yeh said the weekend's earthquake and tsunami were grim reminders that our planet's natural forces are constantly at work – even if we forget about them.

 

"There is such a long period between tsunamis that people tend to forget how dangerous they are, and how devastating their impacts can be," Yeh said. "People in this country forgot about hurricanes for several years before Hurricane Hugo, and this year's series of storms focused people's attention on them again. The lag time for tsunamis is even greater. But the threat is still very real, as we learned."

 

 

Source: Oregon State University

[Aki]

I'm scared now.... I live in the Pacific Northwest region (Vancouver). However the article doesn't really talk about Canada and only talks about the US.

[Turtle]

The primary issue is "Be Prepared". I live in NW (although volcanoes pose more threat to me inland) & Tsunami Evacuation signs have been common on our beaches for some time. We as scientific minded individuals know that everything is subject to change; radical change. Just look at what Chaos Theory has revealed about the inadequacies of Probnability Theory. Just be prepared; chance favors the prepared mind.

[Turtle]

___Just last week we had three 3+ quakes on the Juan De Fuca plate margin. I actually heard a news announcer sya "don't worry about a Tsunami though, the quakes are just part of the spreading center". Good grief!

___They recently tested the coastal Tsunami preparedness in Washington &...well, a lot of people will die. Tsunami signs pointing to nowhere, no sirens, etc. People at best will have a 20 min escape window after the initial quake. That means get the word & pack & leave. Good luck; a lot of people are going to die. :Alien:

[C1ay]

That means get the word & pack & leave.

 

Did you really mean that part about packing? To me a 20 minute warning means get the word and leave. With the sudden traffic jam you'll be lucky to get very far in 20 minutes. I wouldn't think you'd want to waste any of those minutes.

[zadojla]

Did you really mean that part about packing? To me a 20 minute warning means get the word and leave. With the sudden traffic jam you'll be lucky to get very far in 20 minutes. I wouldn't think you'd want to waste any of those minutes.

Just make sure you're carrying ID (so they can identify the body) and essential medications (in case you don't die), then scoot. Pets are on their own, sorry, no time to hunt down and pack four cats.

[[email protected]]

If anyone is interested http://www.earthquake.usgs.gov shows recent earthquakes in the US and all over the world. Today there were 2 5.0 earthquakes just off the coast of Oregon. I don't think thats enough for a tsunami but there has been an increase in small earthquakes along the Aleutian Islands and in Alaska, and of course California. My sister lives in Oregon and I'm worried.

[Buffy]

A couple of things are important to note. The Indian Ocean tsunami was the result of huge section of ocean floor subducting, which caused a gigantic space for the ocean to fill causing a huge wave. The Cascadia/Juan DeFuca junction is a slip/strike fault where the plates move past each other, and this type of movement generally does NOT generate tsunamis (otherwise ya wouda seen a few last week!). Further, the west coast of North America is very rugged and is mostly composed of cliffs of 50 or more feet that would dash all but the biggest tsunamis. There are small towns along the coast that would be inundated, and places like Seattle, Portland and San Francisco would be flooded as the sea surge pushed into the inland waterways that they lie upon, but this would be flooding, not the blast that got most places on the Indian Ocean straight on (even the disaster on the back side of Sri Lanka was due to those areas being on open ocean). Los Angeles and even San Diego are "pointed in the wrong direction" for Cascadia quakes. The one quake in recent memory that *did* cause damage in California was to Crescent City in far north California, and happened due to the Anchorage quake in 1964, not from any movement on Cascadia/Juan DeFuca, which is actually quite active and has been for a long time. What worries the scientists *far* more than the actual quakes themselves are potential underwater landslides (I prime potential site for that happens to be in Monterey Bay), which could be triggered by a very *minor* quake, which would not necessarily generate a tsunami warning (in fact the slide could occur hours or days after the quake with *no* warning). Even then the nature of the coastline protects most people, and even a huge event would come no where near the casualties of the Indian Ocean quake, where so much of the population is right on low lying land.

 

Cheers,

Buffy

[Queso]

what does that mean for the bay area? is the valley safe or will it become a giant pool?

[Turtle]

Buffy said. "The Cascadia/Juan DeFuca junction is a slip/strike fault where the plates move past each other, and this type of movement generally does NOT generate tsunamis (otherwise ya wouda seen a few last week!)." The Eastern boundry of Juan De Fuca IS a subduction /zone interface which is the source of the cascade volcanoes. It can & has generated tsunami. Further the western boundry is a spreading center, ie. underwater line of volcanism, black smokers, & strange lifeforms, not a simple strike/slip fault.

[Buffy]

what does that mean for the bay area? is the valley safe or will it become a giant pool?

Giant pool. Only little bits of Ocean Beach, Half Moon Bay and the Santa Cruz to Monterey coast would get the full brunt of a tsunami. The Golden Gate would act like a valve and limit the damage inside the bay (you prolly would not want to be in the Marina district though!), but the south bay would become a pretty big lake...There was an article in the SF Comical a couple of weeks ago about this, although there's still debate about exactly what would happen.

 

Cheers,

Buffy

[Buffy]

The Eastern boundry of Juan De Fuca IS a subduction /zone interface which is the source of the cascade volcanoes. It can & has generated tsunami... not a simple strike/slip fault.

I take that back. What is true is that most of the earthquakes in the area ihave been generated by slip strikes between the chunks of the several plates that are colliding in the area (the Petrolia/Rio Dell/Eureka area have been hard hit by these a couple of times in the last 10 years), although some big ones in 1949 and 1965 came from the subduction zones. The Northridge Quake in 1994 was a subduction style quake too, but points out that subduction quakes are usually deep underground, and don't produce the drop in elevation that caused the Indian Ocean Tsunami.

 

Lotso good stuff on this area can be found here: http://vulcan.wr.usgs.gov/Glossary/PlateTectonics Take a look at the maps there and you'll see all the slip-strikes I'm talking about...

 

Cheers,

Buffy

[Queso]

Poor santa cruz...that's one of my favorite places in the world.

wow, imagine living on Mt. Hamilton, the eastern side of the valley...you wake up and find a giant lake in your backyard.

p.s. i don't live in california anymore, have all my life, and plan to move back in a few months.

now i'm a little iffy about it...but it's worth the risk. i think i'll tie a raft to my roof so that when i'm flooded, i can swim out, cut the line of the raft, and ride free.

the chances of me not dying between my room, and my roof, is about 1 and a few million though.

[Turtle]

___Here is one map from that source:http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/Maps/map_plate_tectonics_cascades.html

___The important features are the spreading zones & the subduction zone; strike slips are not even labeled here. That is because they are a result of the system, not a cause.

___What is in play here also is no one (geologists, politicians, etc.) wants to unduly alarm the public, while realizing just how dangerous things are. Add further to that the relatively new evidence that quakes in one area have a relation to quakes or volcanoes in another, & you have the situation where no one really knows what's happening.

___I reiterate that each of you as an individual should have an emergency plan. As much as we'd like to have all the answers, geology is far from a fully understood science. Have a plan.

[Queso]

what plan CAN you have though?

i mean honestly, i am extremely optimistic, but if a tsunami is coming over the mountain and you're in the middle of the valley (say..san jose, for example) which has a population of a million, what's there to do? boy i wish i had a helicopter, that would be quite an amazing sight to see.

[Buffy]

The important features are the spreading zones & the subduction zone; strike slips are not even labeled here. That is because they are a result of the system, not a cause.

True, but those thin black lines connecting the spreading zones are the slip-strikes, and they are what are more likely to produce quakes over shorter time spans, because they're pure rock munging against rock. Subduction zones can be "greased" by magma they push into too, although not always, but they can produce MUCH larger quakes, so the subduction quakes are much more dangerous, and you're right to worry. The Northridge (subduction) quake was *miles* underground and the geologists say that if it had been closer to the surface, it could have leveled the entire San Fernando Valley...don't underestimate the slip-strikes, though cuz they occur much more often, and are right there next to you...

 

Cheers,

Buffy

[Turtle]

This is very topical as this week a swarm of quakes has occured (is occuring) on or near these faults. It is the seafloor spreading that puts the pressure on & causes the faults to fracture. Part of the big unanswered question is whether these quakes are relieving pressure on the leading subduction boundry & lessening the danger that it will slip. The faults are relatively short but the subduction boundry is hundreds of miles long & if it slips that is what may generate a tsunami.

___I studied under a fella that went down in Alvin to the black smokers just off the Washington coast. He brought in his own home movies of the tube worms & chimneys; just fascinating.

___I guess the good thing is that the topic is under study & we are making advances in understanding these systems.