Landslides are common in both Earth and Mars, but in Mars, it works in a puzzling way. Scientists have long been researching to find the cause of landslides on Mars that don’t follow an essential law of physics. When a large number of rocks and soil move downslope, mainly because of gravity, they cause “long, runout landslides.”
Nature Communications published a new study which is titled “Longitudinal ridges imparted by high-speed granular flow mechanisms in martian landslides.” Giulia Magnarini and Tom Mitchell are the lead authors of the study from University College of London. They come at a speed of 360 kilometres per hour over flat surfaces for up to ten kilometres. It is likely to say there is no or minimal friction present. Friction resists the motion of one surface sliding relative to another.
Possible Explanations By Scientists
The scientists have provided some possible explanations behind the unusual behaviour of the Martial landslide. To study Martian landslides, the team used Digital Elevation Models (DEMs) based on data from the Mars Reconnaissance Orbiter’s HiRise and CTX cameras.
- Scientists say these landslides must have taken place at a time when the area is covered with ice.
- A layer of water may have lubricated the path that the slide follows.
- Another reason behind reduced friction may be the landslide debris glides over a layer of trapped air.
- The heat gathers the necessary lubrication for the landslide from the friction melting underwater ice, or rock.
However, a new publish in Nature Communications reveals a fact that may be helpful for us protecting against dangerous landslides both on Mars and on Earth. The geologists first identified the odd behaviour of martian landslides nearly half a century ago. Our Earth also had these type of landslides but the presence of erosion, atmospheric weathering, and many other reasons it is masked. The high-resolution satellite images of the surface of Mars help us to have better observation and measurements than our planet.
Valles Marineris, a 4000 km long straight canyon that runs along the Martian surface east of the Tharsis region. It is 200 km wide and up to 7 km deep making one of the largest canyons of the Solar System. Here we can find extraordinary examples of long, runout landslides. Here we will focus on one of the best-preserved landslides with a size similar to the entire State of Rhode Island in the US. The landslides show long ridges that earlier described as a result of underlying ice during the landslide. The presence of the ridges on martin landslides indicates that Mars was once covered in ice.
There is another theory that the experts explain. According to them, the landslide and the ridges also may occur because of an underlying layer of lighter, unstable rocks. Due to the pulverization of larger rocks, that layer may have formed from the action of the landslide itself. Eventually, the lighter rocks would rise due to their heat, and heavier, cooler rocks would fall to the bottom of the landslide.
Mitchell and Magnarini said in their article, “Once we had accounted for this mechanical instability - and coupled it with the movement at phenomenal high speed of the slide - we could show that vortices extending in the direction of the landslide’s movement were generated, giving rise to the long ridges that we observe on the surface of the landslide.”
The discoveries are significant. In our planet, the incomplete record of such catastrophic events may cause misinterpretations and overlook of the hazard of these landslides. They may also occur in future, putting the life of people in risk. However, landslides are still happening on Mars, and these studies will set the background knowledge for risk mitigation of human settlements on Mars.