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50 Years Ago, A Small Taste Of A Pacific Tsunami's Potential Power

OPB | March 27, 2014 midnight | Updated: March 27, 2014 7:15 a.m. | Seaside, Oregon

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On March 27, 1964 a massive earthquake devastated parts of Alaska and triggered a tsunami that swept down the West coast, killing 16 people in Oregon and California. 50 years later scientists warn that the next tsunami may be far more destructive than anything Oregonians have yet experienced.

Tom Horning owns the same Seaside, Oregon home where he was raised — along the banks of the Necanicum river and within earshot of the ocean.

“This is the house I grew up in. My house was not big enough for the entire family so my brother and I stayed in a guest cottage that was over along the river bank,” Horning recalls.

He was sleeping upstairs in that cottage on March 27, 1964 —- when he woke to the sound of waves crashing through the first floor.

“It took away the dock in the river, swept away all the fences we had, floated the car up the street. It got within an inch of entering the main house, swept away a cat we never saw again.”

First Avenue Bridge, Seaside.  View to southwest.  Time of the photo is around 9:30 AM on Saturday.  Part of the 4th Avenue Bridge is caught beneath the east end of the 1st Avenue Bridge.  It acted like a cofferdam and blocked water flow in the main channel of the Necanicum River, deflecting the flow of water to the west. The 1st Avenue Bridge was not damaged. 

First Avenue Bridge, Seaside.  View to southwest.  Time of the photo is around 9:30 AM on Saturday.  Part of the 4th Avenue Bridge is caught beneath the east end of the 1st Avenue Bridge.  It acted like a cofferdam and blocked water flow in the main channel of the Necanicum River, deflecting the flow of water to the west. The 1st Avenue Bridge was not damaged. 

Photo courtesy of Paul See

Horning was lucky. The “Good Friday” tsunami left him unscathed but killed 16 people in Oregon and California. It’s considered the worst tsunami ever to strike the lower 48 states.

50 years later, though scientists have a message for the Oregon coast: You ain’t seen nothin’ yet.

Nate Wood is a geographer with the U.S. Geological Survey. He’s taking in the view along Seaside’s densely developed promenade.

“It’s just a wall of hotels. And a lot of tourists who probably don’t know anything about tsunamis,” Wood says.

According to Wood the tsunami that swept through Seaside’s downtown in 1964 was small, relatively speaking.

His concern is the big one - as in really big one - a tsunami triggered not by some distant earthquake, but by a local one.

Third & Necanicum Drive, Seaside.  View to the south.  City crews begin road cleanup on Saturday morning.  The front-end loader is moving a 12-inch log. Sea foam covers the shoulder of the road and is caught in brush on the right, near the pedestrians.  Foam also covers the First Avenue Bridge, primarily on its west end, where water was diverted by a large piece of the 4th Avenue Bridge, which was washed upstream by the tsunami.  According to people evacuating along Necanicum Drive, the debris dam under the First Avenue Bridge caused flooding on the drive that was about 18 inches deep, or between 13 and 14 ft NGVD.

Third & Necanicum Drive, Seaside.  View to the south.  City crews begin road cleanup on Saturday morning.  The front-end loader is moving a 12-inch log. Sea foam covers the shoulder of the road and is caught in brush on the right, near the pedestrians.  Foam also covers the First Avenue Bridge, primarily on its west end, where water was diverted by a large piece of the 4th Avenue Bridge, which was washed upstream by the tsunami.  According to people evacuating along Necanicum Drive, the debris dam under the First Avenue Bridge caused flooding on the drive that was about 18 inches deep, or between 13 and 14 ft NGVD.

“When the earthquake happens, the big magnitude 8 or 9 earthquake, and the wave shows up in about 20 minutes, you’ve got thousands of people along this waterfront here, that have to realize they are at risk, and would have to start moving.”

Seaside – in fact the entire Oregon coast - sits about 50 miles from the Cascadia Subduction Zone. It was only in the last few decades that geologists confirmed that it’s the source of mega-sized earthquakes and tsunamis that strike every 300-400 years on average.

And the last one was 314 years ago.

How bad will it be?

Jay Wilson is chair of Oregon’s Seismic Safety Policy Advisory Commission. He says we need only look at what happened in Japan in 2011.

Charlie Jackson’s spare parts car pinned against the Creal residence.

Charlie Jackson’s spare parts car pinned against the Creal residence.

Photo courtesy of Bettie Hansen.

“In Minamisanriku, which is kind of the iconic one in Japan for me, and most of that city was under about 30 feet or more of surging water that came in about eight times overnight,” Wilson says.

Oregon is not at all prepared for that kind of tsunami.

In fact it wasn’t until this year that the state revised its maps to show how far inland a local Cascadia tsunami would reach.

In Seaside, 83 percent of residents and 100 percent of Seaside’s critical infrastructure — things like schools, fire stations and civic buildings — are in the impact zone.

Relocating even essential services won’t happen anytime soon.

“At this point, it’s all about the high ground. And getting to the hills east of the city, and trying to you know, get thousand of people mobilized within 20-30 minutes time,” Wilson says.

To that end, Nate Wood hopes a next generation of maps he’s developing for the USGS will help. On a computer he pulls up color-coded satellite images that show, block by block, how long it would take people to reach high ground.

“We see these light blue areas are areas that at a very conservative walking speed people in theory could make it out in time,” Wood says.

Live in a blue area? Move fast. A red area? Move really, really fast.

Wood hopes officials might consider the new maps when siting things like new senior centers and high density housing as well.

“And so if we can have an event that, maybe a thousand people die, unfortunately, instead of twenty thousand people, then I think it’s worth the effort.”

With the discovery of the Cascadia Subduction zone — the worst case scenarios dreamt up by scientists just got a whole lot darker.

Tom Horning, who survived the 1964 tsunami and grew up to become a geologist says people need to recognize that the science is in.

“I’m worried, I really am worried. We know it’s going to happen. We know how bad it will be. The challenge now is trying to convince the public of the truth of it,” Horning says.

The only thing that isn’t known is when the next tsunami will strike.


DOGAMI Tsunami Inundation Map for Seaside

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