Landslides in Alaska
Alaska Division of Geological & Geophysical Surveys
Landslides cause deaths, injuries,
and homelessness every year, and
Landslide damage or destroy buildings,
is a catch-all term
roads, and other infrastructure.
that refers to mass
movement of rock Many regions in Alaska
and soil are especially prone
to landslides.
Changing climate in Alaska Landslide damage, 1964 Great Alaska Earthquake
increases the risk of landslides Alaska’s climate and geology
Increases in tsunami-producing landslides in Southeast result in landslide trigger
Alaska can be attributed to retreating glaciers and thawing mechanisms such as:
permafrost. Collapse of hanging glaciers and rock-ice Permafrost degradation
Glacial retreat
faces is most common in areas with glaciers and steep Earthquakes
topography—frequently the same areas that attract Isostatic rebound
tourists. These types of landslides are among the most The above trigger mechanisms
dangerous to people and infrastructure. can cause some unique types
of landslides:
Studies show that changing climatic conditions, like Snow-ice-rock avalanches
increased rainfall and permafrost degradation, can Frozen debris flows
increase the frequency of fast-moving, catastrophic
landslides. Alaska’s warming climate has already
caused many areas to become unstable. Future
warming will increase landslide risk throughout the
state, especially in permafrost and glacial regions. At
the same time, population growth and the expansion
of settlements and lifelines over potentially hazardous
areas are increasing the impact of landslides.
Landslide maps help raise Sitka Debris Flows. On August 18,
awareness and promote public safety 2015, heavy rains resulted in numerous
landslides in and around Sitka, Alaska. More
Very few landslide maps exist for Alaska. Investing in land- than 45 landslides were initiated during
slide maps helps raise public awareness of landslides and this rainfall event. Four debris flows (very
water-rich landslides) impacted homes and
their consequences, and promotes public safety. By providing infrastructure in Sitka, and this one took the
up-to-date awareness of areas of instability before problems lives of three Sitka residents.
occur, landslide maps save time, money, and lives. Read about other recent Alaska landslides
on the back.
Learn more online: dggs.alaska.gov
or contact De Anne Stevens: deanne.stevens@alaska.gov | 907-451-5014 IC 65 | http://doi.org/10/14509/29849
Recent Alaska Landslides
Alaska Division of Geological & Geophysical Surveys
Debris runout on
Lamplugh Glacier
Cruise ship
Lituya Bay Landslide. On July 9, 1958, a
magnitude 8 earthquake along the Fairweather Lamplugh Glacier Snow-Ice-Rock Avalanche. On
Fault dislodged about 40 million cubic yards June 28, 2016, a massive landslide crashed onto a
of rock from a mountainside, sending it 3,000 glacier in Glacier Bay, Southeast Alaska. More than
feet downslope into Gilbert Inlet. The wave that 100 million tons of rock, snow, and ice slid down
followed surged 1,720 feet up a mountain slope a mountainside, sending debris six miles down
and left trimlines along the bay that are still Lamplugh Glacier. Snow-ice-rock avalanches like this
visible today. are becoming more common with receding glaciers.
Yukon River Bridge Landslide. In 2012 a landslide
Area of occurred approximately 375 feet from the Dalton
landslide Highway bridge over the Yukon River. The Dalton
Highway and the Trans-Alaska Pipeline System rely
on the bridge to connect Fairbanks to the Prudhoe
Bay oilfields, ensuring an uninterrupted corridor
for the transportation of supplies and personnel.
Any compromise to the bridge’s integrity could
potentially have immediate and severe consequences
to the state’s economy and environment. Although
there was no damage to the bridge foundation,
Yukon River Bridge—Dalton the landslide’s close proximity to the bridge raised
Highway/TAPS concerns over additional potential failures.
Icy Bay Landslide. After a period of heavy rains,
a mountainside near Tyndall Glacier collapsed on
October 17, 2015, dropping 200 million tons of
rock into a fjord of Icy Bay. The displaced water
generated a wave that denuded vegetation more
Area of
than 500 feet up on a hillside across from the slide. landslide
Before After
Trimline
IC 65 | http://doi.org/10/14509/29849
