In the Martian North Pole, there lies two impact craters characterized by moraine-like ridges (accumulations of dirt and rocks), which are generally produced in the wake of glacial movement. In this vein, some scientists suggest that slow-moving CO2 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 alternate theory, a team of researchers led by Sergey Krasilnikov of the Russian Academy of Sciences have used open-source data from NASA to simulate the hypothesized catastrophic surges of material down the slopes of the craters. In their models, accumulations of water ice at the top of the slopes (called massifs) buckle under the enormous weight and pressure, causing a rapid downslope speed of up to 80 meters per second (262 feet per second). This surge, they suggest, could have pushed debris to their edges, forming the observed ridges.
Not only were these avalanches found to be fast-moving, but they were also far-reaching. In one crater, the surge extended to about 15 kilometers (9.32 miles), whilst in the other crater it hurtled 12 kilometers (7.46 miles). An Earth analog of these events was the 2002 Kolka Glacier catastrophe, whose glacial surge and high-speed ice-water-stone mudflow caused devastation along a 17-kilometer-long stretch (10.6 miles).
Published in Planetary and Space Science, the study questions the slow-moving CO2 glacier model, based on the time at which the moraine-like ridges were formed. CO2 glaciers are thought to only occur 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, note the authors, is consistent with the build-up of water ice massifs that could reach a critical point and spark an avalanche at the crater’s Martian latitudes. According to their simulations and calculations, the ice massifs may have built up to between 100 meters (328 feet) and 150 meters (492 feet) tall, heralding a 1.1 and 2.42 square kilometer (0.42 and 0.93 square mile) chunk of ice, respectively, to careen down the craters.
Whilst the debate on how these Martian crater ridges formed will likely continue, this latest study certainly waves the flag for ice avalanches.