Spectacular landslide of the Vavilov ice cap
Spectacular landslide of the Vavilov ice cap
In recent years, the Vavilov ice cap in the Russian Arctic has accelerated dramatically, reaching sliding speeds of up to 25 meters in a single day. That significantly dwarfs the previous average ice velocity of about 5 centimeters per day, and has challenged scientists' assumptions about the stability of the cold ice caps that dot the high latitudes of Earth.
The research was done by Mike Willis, a professor of geology at the University of Colorado in Boulder, United States.
"In a climate that is heated, the acceleration of glaciers is becoming increasingly common, but the rate of ice loss at Vavilov is extreme and unexpected," says Willis.
There is no precedent for such an acceleration and the authors of the new study believe that their finding raises the possibility that other currently stable ice caps are more vulnerable than expected.
For the new evaluation, the researchers practically practiced forensic ice detectives, reconstructing the deterioration of the ice cap by observing the advances of the ice in photos taken from satellites. In them, they could appreciate how the ice in the cap slowly crawled forward for years, before starting to accelerate in 2010, and shoot in the same direction in 2015. It is believed that the very slow initial advance caused a change in the Direction of rainfall, which happened about 500 years ago. Before then, snow and rain came from the southeast, while later they came from the southwest. As the western part of the ice sheet advanced towards the ocean, the ice rushed forward.
In recent years, the sliding of the Vavilov ice sheet has experienced a spectacular acceleration, as shown by the succession of years labels on the ground, very close together the oldest ones, to the right, and very separated from the rest and from each other. two last ones marked (2015 and 2016, on the left). (Image: compilation by Whyjay Zheng / Cornell University, using Landsat images from NASA and the USGS)
The researchers suspect that the ice cap began to move dramatically when its bottom became more humid and the front of the glacier advanced on very slippery marine sediments. The ice began to accelerate, and the friction caused part of it under the glacier to melt, which provided more water to its bottom, reducing friction. This caused the ice to accelerate, which in turn produced more water again. Part of this water could have been combined with clay under the glacier, further reducing the friction below it and allowing the extraordinary speeds of sliding that occur.
By 2015, the sediments and rock in the bed under the ice had become so slippery that the material could not stop the ice from flowing. It took only two years for the base of the ice cap to reach that inflection point, becoming an almost frictionless area, very mobile and well lubricated. The glacier continues to slide currently at abnormally fast speeds, from 5 to 10 meters per day.
.
.
SOURCE LINK ERESVIRAL.COM https://www.beviral.online
Comentarios
Publicar un comentario