An open letter from a group of scientists to the Alaska Department of Natural Resources contains a warning that a landslide may be about to occur in Prince William Sound, with the potential to trigger the largest tsunami of modern times. The alert comes after satellite images revealed that a large mountain slope has been left unstable as a result of a retreating glacier, with the authors stating that “it is possible that this landslide-generated tsunami will happen within the next year, and likely within 20 years.”
It’s important to note that this impending disaster is not guaranteed to occur, as the scientists concede that the slope could yet stabilize. Alternatively, it may only partially collapse, resulting in a much smaller and less destructive tsunami. However, in their report, which has not been peer-reviewed, the authors claim that a total collapse appears “plausible”.
The slope in question is located in Barry Arm, above the toe of the receding Barry Glacier, which lies some 97 kilometers (60 miles) east of Anchorage. Satellite imagery shows that a slow-moving landslide has been in progress for some years, with the mass of rock having slipped 185 meters (607 feet) between 2009 and 2015.
Though the rate of movement has since slowed, the scientists behind the open letter say that a complete collapse “could happen any time”. Should this transpire, the tsunami produced is likely to eclipse that that occurred at Greenland’s Karrat Fiord in 2017, where a landslide triggered a wave that destroyed a large portion of the town of Nuugaatsiaq, some 32 kilometers (20 miles) away.
Among the authors is Dr Chunli Dai from Ohio State University, who studies landslides in the Arctic using a modeling program called ArcticDEM. In a recent interview with NASA’s Earth Observatory, Dai explained that if the rock face at Barry Arm was to collapse, then the narrow shape of the fjord would cause the resultant wave to become amplified to dangerous proportions.
“Based on the elevation of the deposit above the water, the volume of land that was slipping, and the angle of the slope, we calculated that a collapse would release 16 times more debris and 11 times more energy than Alaska’s 1958 Lituya Bay landslide and mega-tsunami,” Dr Dai explained.
That particular event triggered what is believed to be the largest tsunami of modern times, reaching a height of 524 meters (1,720 feet).
The prospect of an even larger tsunami in the very near future in an area that is frequented by shipping vessels and cruise ships could have disastrous consequences, which is why the authors are hoping to collaborate with the National Tsunami Warning Center to monitor the landslide.