Last fall's massive Icy Bay landslide launched a megatsunami

Alaska Dispatch News ^ | 4/9/2016 | Chris Larsen

[JimSEA]

A landslide last fall caused a giant wave not seen in Alaska since a storied 1958 event in Lituya Bay.

After a period of heavy rains, a mountainside near Tyndall Glacier collapsed into a fiord of Icy Bay on Oct. 17, 2015. The displaced water generated a wave that sheared alders more than 500 feet up on a hillside across from the slide at the Southeast Alaska location.

To put that in perspective, the 2011 tsunami in Japan reached about 130 feet above sea level. The Icy Bay wave may be the largest since a magnitude-8 earthquake shook much of a mountain into Lituya Bay on a July day in 1958. The wave that followed ripped spruce from 1,700 feet up a mountain slope and left trim-lines in the bay that are visible today.

Last October, seismologists at Columbia University in New York detected the Icy Bay landslide on their instruments. Göran Ekström and Colin Stark specialize in picking up landslide signals. They figured the slide spilled 200 million tons of rock in 60 seconds.

Winter snows hid the extent of the wave generated from the rock avalanche. Upon hearing a report from a pilot colleague the landslide area of Icy Bay was free of snow, glaciologist Chris Larsen flew there in his Cessna 180 from his home in Fairbanks. The Geophysical Institute professor used a camera system mounted in his plane to make a high-resolution map of the landslide and the path of the megatsunami.

[JimSEA]

This photo is of the aftermath of the 2015 landslide generated tsunami However, A tsunami with a record run-up height of 1720 feet occurred in in Lituya Bay, Alaska in 1958.

[Attention Surplus Disorder]

Pretty intereswting. There is a better before-after pic set here http://blogs.ei.columbia.edu/2015/12/18/detecting-landslides-from-a-few-seismic-wiggles/

Many of the Norweigian fjords (where I traveled many times working aboard a RCCL ship) experienced this as well, 600 foot high waves from a icefall or rockslide. Spectacular scenery, unbelievable.

[combat_boots]

1720’

Wow

[Mase]

Pretty incredible. Here's a before and after shot that shows just how much of the area went into the water.

[xp38]

I’m definitely not pining for the fjords right now. :)

[Attention Surplus Disorder]

Should you pine, try to confine your pining to the July-August zone.

I am not especially reco’ing a trip to Norway et al under present conditions. But I enjoyed the Norway-Finland-Sweden-Estonia-Denmark-St Pete circuit about 7 times in 2005.

[JimSEA]

Incredible!!

[T-Bone Texan]

I’m reading all about the 1958 incident in Lituya Bay.

Fascinating, thanks for the great link.

[JimSEA]

That’s a much better article overall. Thanks for posting.

[Delta 21]

Hydraulics is a wonderful thing.

[Night Hides Not]

[PLMerite]

If we’re just hearing about it now, I’m assuming only moose and sasquatch were affected?

[JimSEA]

Pretty much. However, these sort of landslide generated tsunamis can happen in a lot of different locations. In particular volcanos can present these sorts of land slides.

[dainbramaged]

Lituya Bay is an incredible place - it has a treacherous, narrow entrance navigated by lining up range markers and entering at slack tide - unless you want to soil yourself, or die.
The French explorer LaPerouse tried it at the wrong time and lost 21 men in a longboat in 1786.
A salmon troller named Edri survived the 1958 tsunami and spent many more years in Southeast Alaska - I knew the owner back in the 80's, not the original skipper. He got crazy drunk and was shot by the Hoonah cops, they left him laying on the dock for several hours but he lived. He later collected a ton of money for that incident.

[ken5050]

One of the Azores is supposedly ready to send about half its land mass into the Atlantic. The resulting tidal wave will wipe out the entire east coast of the US

[MarchonDC09122009]

I remember reading about several of the boats that were in the path of that 1958 Alaskan bay landslide tsunami which I think happened at night.
Can you imagine what a 1700’ tsunami looks, sounds and feels like?
Ho Lee Crap.

RE: “A salmon troller named Edri survived the 1958 tsunami and spent many more years in Southeast Alaska”

[MarchonDC09122009]

Poor Wash DC, NYC & Boston!
On second thought...
/s

RE: “One of the Azores is supposedly ready to send about half its land mass into the Atlantic. The resulting tidal wave will wipe out the entire east coast of the US”

[ken5050]

Found it! It's the Canary Islands..not the Azores...here's the video clip

Supposedly the treat has been downgraded the last few years...like they know....

[dangus]

Don’t imagine that there was a 1700’ tall wave.

The 130’ Japanese Tsunami wave was only a few feet.

They are called “tidal waves” because they come in like a tide that just won’t quit, not like a gigantic breaker.

And yes, “tidal wave” is a better name than Tsunami, which means “harbor wave,” although many scientists prior to Indonesia’s and Japan’s had denigrated the name “tidal wave” because they had never seen on camera why they were called that.

[JimSEA]

That’s the one I was trying to think of. Almost any ocean edge volcano can present that risk. Quite often somewhat loosely compacted ash moves on downhill when rain permeates and lubricants the material.