Earlier this year, scientists warned Alaskan residents of a possible tsunami-landslide combo due to global warming. More recently, researchers conducted a lidar survey above Barry Arm, a glacier in the Prince William Sound, to confirm the possibility of a glacial landslide causing a tsunami.
One of the most notable Alaskan tsunamis occurred in 1958 after a 7.8 magnitude earthquake triggered a rockslide in Lituya Bay. The resulting tsunami was about 1720 feet tall.
Due to current global warming trends, fear researchers, a similar event may occur as glaciers continuously retreat, endangering coastal communities. Whittier's city would be one of the cities facing the severe consequences of climate change as they did during 1958.
Climate Change Affecting the Barry Arm
Researchers have concluded that the Barry Arm may be the most dangerous threat to the coastal communities. According to geologists, if the Barry Glacier collapses, the result may be 10 times worse than the previous event.
Since 1957, the Barry Glacier began retreating into the ocean. As the glacier retreated, the slope's support system was declining as well. Since 2006, at least two miles of the glacier has receded. While some data predicts that the slope may fall by 2040, it is also possible for the Barry Arm to collapse before 2021.
Geologist Brentwood Higman from Ground Truth Alaska said that even if these events weren't triggered by climate change, landslide-causing tsunamis are still "worth worrying about." However, global warming does make these events more likely.
The land above the frozen glaciers is made of large rocks and dirt. As their support system recedes from underneath, the dramatic thaw causes the structure above to slide down the mountainside and sea.
Precipitation can also trigger this activity, explained the researchers. As the atmosphere gains more water due to melted permafrost, glaciers, and the like, it results in more precipitation. Storms become more intense, and so do earthquakes, which trigger landslides as well. Moreover, climate change will trigger landslides more frequently.
Urgent Assessment of Unstable Slopes
Anna Liljedahl of the Woodwell Climate Research Center said that an "urgent...assessment where we have these unstable slopes" is necessary to protect the local communities against this "new emerging hazard." By tracking the slopes, the government will install warning systems so that people are prepared when these events arrive.
Kelly Bender, who works in tourism with her husband in Prince William Sound, said that the danger is despite the advisory by local scientists, the locals feel like they know what to do when a tsunami comes along. On her part, she's had to change tours via water taxis or kayaking and canceled several events.
When Gabriel Wolken of the Climate and Cryosphere Hazards Program conducted the air survey using a laser scanner (lidar survey), the data showed how the landslide has changed since June this year. He's noted new rockfalls from every return visit to the mountain. The data hasn't been completely processed yet, but just by looking at Barry Arm from above, Wolken could see that the structure is unstable and that "it's basically falling apart."
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