Stay Eat Events Weather Beaches

Oregon Coast Science: Why No Tsunami with the Alaska Earthquake?

Published 01/23/2018 at 7:45 PM PDT - Updated 01/23/2018 at 10:45 PM PDT
By Oregon Coast Beach Connection staff

Oregon Coast Science: Why No Tsunami with the Alaska Quake?

(Oregon Coast) – Early Tuesday morning saw something startling for Oregon coast residents: a tsunami watch issued because of a 7.9 earthquake off the Alaskan coast. After two or so tense hours, filled with some locals heading inland anyway, the watch was lifted and those who weren't still sleeping through it could rest easily.

Meanwhile, in Alaska things were not so laidback. Tsunami alert sirens went off in many parts of Alaska and even British Columbia, waking residents and calling for evacuations to higher ground. Those warnings were finally lifted too. However, a six-inch tsunami wave was recorded coming into one section of Alaska beach.

It all hearkened back to the great quake of 1964, which killed over 100 in Alaska and caused a tsunami wave that inundated Seaside, killed four children on a beach in Newport and washed out the bridge at Cannon Beach (which in turn caused the creation of the now famed Cannon Beach Sandcastle Festival).

Not that anyone wanted this, but why no tsunami with this quake?

Latest Coastal Lodging News Alerts
In Seaside:
Includes exclusive listings; some specials even in summer
In Cannon Beach:
Includes rentals not listed anywhere else
In Manzanita, Wheeler, Rockaway Beach:
Check each listing for specials
In Pacific City, Oceanside:
Some Deals even in summer; great packages
In Lincoln City:
Major price drops on some dates and some lodgings
In Depoe Bay, Gleneden Beach:
Specials can still be found
In Newport:
Includes exclusive listings not found anywhere
In Waldport
New amenities offered; specials
In Yachats, Florence
Some specials; lodgings not listed anywhere else

The USGS and geologists on the Oregon coast – including Seaside's Tom Horning – have the answer.

Unlike that quake in '64, or the big one expected off the Oregon coast someday, this was a kind of underwater earthquake that simply does not displace much water. This was a strike-slip fault, meaning the two chunks of landmass slide against each other horizontally instead of vertically.

The big nasty coming to this coastline is part of a fault system that will cause a subduction quake – where two plates pop against each other suddenly in an up and down direction, instead of side to side. It's also known as a thrust quake, according to scientists.

This one was side to side – of the strike-slip variety.

Oregon Coast Lodgings for this - Where to eat - Maps - Virtual Tours

“Usually, little vertical displacement takes place, so there isn't a tsunami,” Horning said.

Still, Horning said, these kinds of quakes are capable of creating tsunami chaos. If a submarine strike-slip rattler causes massive underwater landslides, shaking up debris from the continental shelf, then tsunamis can occur. This was just the situation from another Alaska-centered shaker in 1946 that caused extensive damage in Hawaii.

If this sort of quake were to occur on land – as it does with the San Andreas fault in California – it can bend train tracks and tear fences apart.

In a subduction zone, like that off the Oregon coast, it is the result of one continental plate shoving itself underneath another. When that tension releases, one plate drastically moves up or down. This will cause substantial movement of ocean water, resulting in a tsunami.

It takes a 7.0 magnitude quake to generate a tsunami. Small quakes around magnitude 2 to 3.5 occur about 20 times a year off the Oregon coast.

Oregon Coast Lodging

 






More About Oregon Coast hotels, lodging.....

More About Oregon Coast Restaurants, Dining.....

 

Oregon Coast event or adventure you can't miss

 



Coastal Spotlight


LATEST Related Oregon Coast Articles

Looking Back: March '64 Tsunami That Wrecked Oregon Coast, Photos
On March 27, 1964, it was anything but a good Friday when the infamous Good Friday quake hit Alaska
Chillin' in Retrospect: Oregon Coast in the Snow
When snow does hit the Oregon coast it's always a grand entrance
From March 25: No Tsunami Threat for Oregon, Washington Coast, Hawaii
An updated special statement about an earthquake offshore from Russia, saying there is no threat. South coast
View Oregon Coast Whale Watch Week Online: Updated Daily (Orca Footage)
Luckily, you can still watch them as you 'shelter at home' and perhaps keep your sanity a little longer
When a Mysterious Shipwreck Popped Up Out of Nowhere: Oregon Coast History
Ten years ago, a 100-year-old surprise popped up on the north Oregon coast, essentially forgotten by time
Oregon Coast, Washington Slowly Close Down Beaches, Towns: Latest Shutdowns
State parks around Oregon are shut down, some towns have closed themselves to tourists, with many beach accesses now closed off. South coast, warnings
Be at the Oregon Coast from Afar - Living It Vicariously
There are indeed ways to check out these lovely beaches from afar - digitally. Washington coast, south coast, sciences
The Little Critter That Looks Like a Spaceship on Oregon / Washington Coast
It's called the longnose skate: a dark, sleek and thin creature. Sciences, South Coast

Back to Oregon Coast

Contact Advertise on BeachConnection.net
All Content, unless otherwise attributed, copyright BeachConnection.net Unauthorized use or publication is not permitted

Oregon Coast Lodging
Rentals
Specials

Dining

Events Calendar

Oregon Coast Weather

Travel News

Search for Oregon Coast Subjects, Articles

Virtual Tours, Maps
Deep Details