Tag Archives: glaciers

Alaska Jökulhlaup

A large glacial dam gave way in Southeast Alaska this summer. Known by its Icelandic term: jökulhlaup, the power of this sudden release of pent up water can be incredibly destructive.

The terminus of Lituya Glacier; Photo credit: NPS/J. Capra

Desolation Lake, which sits above the Lituya Glacier in Desolation Valley, collects meltwater from both the Desolation and Fairweather Glaciers. That meltwater is normally blocked by the Lituya Glacier, forming the roughly four square mile lake.

The water level suddenly dropped 200 feet.

A commercial fisherman, Jim Moore, along with his two grandsons, tried to enter Lituya Bay to fish for Chinooks in August. They should have been riding the tide into the bay, but the unusually muddy water was moving outward, and it was filled with trees and other debris. The bay was also filled with small icebergs. Moore managed to bring some of the ancient ice onboard for his coolers, then left the bay, instead of fighting the dangerous current.

Lituya Glacier terminus and delta; Satellite image credit: USGS

It is one of the largest jökulhlaups known to have occurred in Alaska. The water found a path under the Lituya Glacier, causing a rush that would have rivaled the hourly discharge of the Amazon River. It would have lasted for several days.*

Lituya Bay has a history. In 1958, an earthquake triggered a landslide that started one of the largest known tsunamis at over 1700 feet.

*NPS Geologist, Michael Loso


Taku Glacier & the Juneau Ice Field

The Juneau Ice Field, as seen from the air

The Juneau Ice Field is located just north of Alaska’s capital city. The ice field covers 1500 square miles, more than a third larger than Rhode Island, and stretches from Alaska across the border into British Columbia. The ice field is home to over 40 large glaciers and more than 100 smaller glaciers. The Juneau Ice Field has been one of the most studied in the world, with the Juneau Ice Field Research Project being conducted annually since 1946.

Taku Glacier, as seen across the Taku River

One of the most talked about glaciers within the Juneau Ice Field has been Taku Glacier. It has been the last advancing glacier within the ice field. It’s “mass balance” has been in the positive; it has been gaining more snow during the coarse of a year than it has lost in melt.

Taku Glacier from the air

Taku is the thickest measured glacier in Alaska. It is considered a high elevation glacier, which has helped it maintain the title of an advancing glacier.

That designation has officially come to an end. With the increasingly warm temperatures that Alaska has been experiencing over the past decade plus, the Taku Glacier is now retreating.

When Taku has calved in the past, it has sent icebergs into the Juneau harbor. Massive calving events would not only send icebergs to Juneau, but also into the Inside Passage.

When Columbia Glacier in Prince William Sound started its retreat, sending icebergs into The Sound, the State of Alaska was forced to create an ice-watch program for oil tankers and cruise ships.

Taku Glacier is twice the size of Columbia.