At the Martian North Pole are two impact craters characterized by moraine-like ridges (accumulation of dirt and rocks), which are usually produced in the wake of glacial movement. In this sense, some scientists suggest that COtwo glaciers may be responsible for the linear structures seen in these Martian craters. However, others are taken by a much more dynamic origin: massive ice avalanches.
To test this alternative theory, a team of researchers led by Sergey Krasilnikov of the Russian Academy of Sciences used open-source data from NASA to simulate the supposed catastrophic surges of material on the slopes of craters. In their models, water ice accumulations on top of slopes (called massifs) bend under the enormous weight and pressure, causing a rapid descent speed of up to 80 meters per second (262 feet per second). This wave, they suggest, may have pushed debris to its edges, forming the ridges seen.
These avalanches not only moved quickly, but were also far-reaching. In one crater, the wave extended to about 15 kilometers (9.32 mi), while in the other crater it reached 12 kilometers (7.46 mi). A terrestrial analogue of these events was the Kolka Glacier catastrophe in 2002, whose glacial wave and high-velocity rock-water-ice mudflow caused devastation along a 17-kilometer-long (10.6-mile) stretch.
Published in Planetary and Space Science, the study questions COtwo glacier model, based on when the moraine-like ridges were formed. COtwo Glaciers are thought to occur only when Mars has a low axial tilt, which hasn’t happened in the last 10 million years, Krasilnkov told Eos. However, the crater ridges likely formed within the last few million years.
This period, the authors note, is consistent with the accumulation of water ice masses that can reach a critical point and trigger an avalanche at the crater’s Martian latitudes. According to their simulations and calculations, the ice masses could have built between 100 meters (328 ft) and 150 meters (492 ft) in height, heralding a patch of ice of 1.1 and 2.42 square kilometers (0. 42 and 0.93 square miles), respectively, to descend the craters.
While the debate over how these Martian crater ridges formed is likely to continue, this latest study certainly waves the ice avalanche flag.
If you want to see a confirmed ice avalanche on Mars, check out this image captured by NASA’s Mars Reconnaissance Orbiter (MRO) as the north polar ice cap melted last year.