While the surface of Mars now appears relatively unchanged, it wasn’t always like that. The highest mountain in the Solar System is Mount Olympus, a giant shield volcano on Mars, reaching a height of 21.9 km (13.6 miles), which is 2.5 times Mount Everest on Earth. Ancient lava flows surround the volcanic caldera and indicate an active time.

New images taken by ESA’s Mars Express show how these lava flows form extremely sharp cliffs up to 7 km (4.3 mi) high in some areas, and these cliffs suddenly collapse in dramatic landslides. One of these landslides occurred 100 million years ago when a part of the volcano broke off and spread to the surrounding plains. If we could look back and see how this happened, it was definitely a very dramatic and turbulent time on Mars.

Images captured by the Mars Express High Definition Stereo Camera (HRSC) show a wrinkled feature called Lycus sulci at the edges of the petal; The volcano itself is out of frame in the lower left corner (southeast) of the above image, hundreds of kilometers away, but can be seen in the images below.

Combining the new images with data and topographic data from NASA’s Orbiting Laser Altimeter helps tell the old story of how the lower flanks of Mount Olympus collapsed disastrously 100 million years ago. ESA scientists say large volumes of lava once flowed down the volcano, triggering landslides, which rolled down slopes and collided with bedrock (in this case, rock containing ice and water), ESA scientists said.

This image shows the wrinkled perimeter of Mount Olympus and an object called Lycus Sulci on the raised rim around the volcano. Image credit: NASA/MGS/MOLA Science Team

The hot lava caused the ice to melt and become unstable; As a result, the rocky edge of Mount Olympus broke and partially slipped. This collapse took the form of massive rockfalls and landslides that slid down and spread to the surrounding plains. As landslides progress on the land, they crumple and separate from each other, forming a wrinkled surface. Strong Martian winds then swept over the solidified lava flows, turning them into the softened wrinkles we see today at Lycus Suls.

Mount Olympus photographed from orbit by ESA’s Mars Express mission. Credits: ESA/DLR/FUBerlin/AndreaLuck

Scientists see these features on Earth as well, though not as massive and common as on Mars. Similar but smaller landslides can be seen on the volcanic islands of Hawaii and the Canary Islands, which have been subject to major rockfalls in the past.

Mars Express has been sending us amazing images of Mars since 2003. Besides imaging, it maps minerals, determines the composition and circulation of its sparse atmosphere, and studies how various events interact in the Martian environment. Source