New findings about Martian landslides

A new study, published in Nature Communications, reveals new evidence about Martian landslides.

The surface of Mars consists of large ridges that were formed 400 million years ago and were a result of intense landsliding of the ground. Until recently, it was considered that those landslides derived from the ground's movements on ice layers. However, the new evidence doubts the presence of those ice sheets below the Martian surface.

Those ground movements were similar to landslides on Earth that occurred on top of glaciers, a fact that led scientists to believe that this was also the case on Mars. “Landslides on Earth, particularly those on top of glaciers, have been studied by scientists as a proxy for those on Mars because they show similarly shaped ridges and furrows, inferring that Martian landslides also depended on an icy substrate," Giulia Magnarini, lead author of the study and Ph.D. candidate at the UCL (University College London), stated.

Scientists studied a large Martian landslide that stretches over a length of 55 kilometers. They analyzed a series of 3D images of the region retrieved by NASA's Mars Reconnaissance Orbiter to understand how those ridges and certain channels in the ground were formed. The study suggests that those movements could have occurred on layers of fragmented rocks. "We’ve shown that ice is not a prerequisite for such geological structures on Mars, which can form on rough, rocky surfaces. This helps us better understand the shaping of Martian landscapes and has implications for how landslides form on other planetary bodies including Earth and the Moon,” Magnarini added.

The correlation between the altitude of the ridges and the width of the channels with the thickness of the debris layer was investigated by creating cross-sections in the surface of the ground. The results showed that the scenario of a rocky substratum is feasible. “While we aren’t ruling out the presence of ice, we know is that ice wasn’t needed to form the long run-outs we analyzed on Mars. The vibrations of rock particles initiate a convection process that caused upper denser and heavier layers of rock to fall and lighter rocks to rise, similar to what happens in your home where warmed less dense air rises above the radiator.  This mechanism drove the flow of deposits up to 40 km away from the mountain source and at phenomenally high speeds,” Dr. Tom Mitchell, co-author of the study and Associate Professor of Earthquake Geology and Rock Physics at UCL, said.

Harrison Schmitt, Professor at the University of Wisconsin Madison and the first scientist to walk on the moon with Apollo 17 mission (in 1972) to conduct geologic fieldwork, was a member of the scientific team. Prof. Schmitt stated that this study will further aid in understanding the lunar and Martian landslides and will help geologists make comparisons to draw useful conclusions.