A 200-meter tsunami hit Alaska, but no one noticed. Scientists have found that the melting of glaciers can cause such natural phenomena in other parts of the world.
A tsunami with a height of almost 200 meters is not a fantasy or an invention of Hollywood directors. Such extreme events occur on Earth, and the latter happened just recently - only three years ago, off the coast of Alaska.
What happened in October 2015 in the Taan Fjord in the southeast of the state, scientists call the fourth largest tsunami, reliably recorded, however, already post factum, over the past hundred years. And its cause - the melting of the glacier, which led to a giant landslide, leads scientists to believe that such catastrophic events in the future may increasingly occur in different parts of the world. “More and more of these landslides will occur as mountain glaciers and permafrost melt,” suggests a team of authors led by Bretwood Hyman in an article published in Scientific Reports.
“40 years ago the Taan fjord did not exist at all. It was filled with ice,”explained Dan Sugar, a geophysicist at Washington State University in Tacoma, one of 32 authors on the paper, including scientists from the United States, Canada and Germany.
However, between 1961 and 1991, the Tyndall Glacier retreated by about 300 meters and stopped in its current position. However, the retreat of the glacier from the coastal entrance not only completely exposed the fjord. This process has moved the ice that previously propped up a huge mass of rocks that had lost their support.
Calculations showed that about 180 million tons of stones and soil fell into the bay as a result of a landslide, which caused a tsunami.
When a mass of stones deprived of support rushed into a rather narrow bay, this led to the emergence of a huge tsunami, the wave of which swept at a speed of about 100 kilometers per hour, scientists calculated.
“Imagine a bowling ball being thrown into your bathtub,” Sugar explained. - The water will move in all directions, but when it hits the wall, it will have nowhere to go. And the only way out will be up."
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According to the specialist, this tsunami was not the highest known to science, but close to record ones. By the way, its destructive effect extended about 20 kilometers along the coast of the fjord.
“The highest documented tsunami was in Lituya Bay, and it was quite a similar event - the landslide went down, touched the tip of the glacier and entered the water of the fjord,” Sugar explained. "In that case, it was preceded by a major earthquake."
Then, in 1958, the height of the tsunami that hit the shore reached 500 meters, and five people became victims.
The seismic response helped the scientists to understand that a landslide had descended in the Taan fjord, and they arrived there relatively quickly - eight months later. On the spot, they began to survey the coastline, fallen trees, piles of stones and other debris brought by the tsunami.
Fallen trees in Alaska.
As a result of this giant tsunami, observed in a closed fjord, no one was hurt, but scientists admit that inside such a fjord at the wrong time, for example, there could be a cruise liner. In addition, not so long ago, a similar tsunami caused by the melting of a glacier in Greenland killed four people.
Based on their findings, scientists propose to search for and monitor similar places on Earth. In their opinion, such tsunamis can create a danger off the coast of Greenland, Patagonia and Norway. "The authors are definitely right in suggesting that potential threat zones be identified, mapped and tracked to minimize future tsunami damage caused by landslides," said Martin Luthi, a geographer at the University of Zurich who was not involved in the study.
“The landslide and tsunami caused by glacier melting in Taan Fjord demonstrates the threat posed by climate change,” the authors write. Meanwhile, tsunamis are not the only catastrophic consequences that could be caused by melting glaciers. In the mountains, the melting of ice can lead to the formation of alpine lakes, which at one point can break through, causing landslides and floods with serious consequences.
On the eve of the Ministry of Natural Resources, it warned that numerous natural disasters threaten the territory of Russia as a result of global warming, which is happening in our country faster than the average on the planet. It is possible that Russians will soon face droughts in some regions and floods in others. These processes will entail the destruction of burials of radioactive substances and civil infrastructure, destruction of crops, shutdown of power plants and ultimately - technological disasters. Melting permafrost will bring irreversible disasters.