Over 100 Million Years Ago, Olympus Mons Had a Massive Landslide

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While the surface of Mars looks relatively unchanging now, it wasn't always so. The tallest mountain in the Solar System is Olympus Mons, a giant shield volcano on Mars that reaches 21.9 km (13.6 miles) high, 2.5 times higher than Mount Everest here on Earth. Ancient lava flows surround the volcanic caldera, evidence of an active time.

New images from ESA's Mars Express show how these lava flows created extremely sharp cliffs, as high as 7 km (4.3 miles) in some areas, which suddenly collapsed in mind-boggling landslides. One of these landslides occurred several 100 million years ago when a chunk of the volcano broke off and spread across the surrounding plains. If we could look back in time and see as it happened, it was certainly a very dramatic and turbulent epoch on Mars.

The images, from Mars Express' High Resolution Stereo Camera (HRSC), show a crumpled feature named Lycus Sulci, on the edges of the aureole; the volcano itself is located out of frame to the bottom left in the image above -- (south-east), many hundreds of km away, but visible in the images below.

Combining the new images with data with topographical data from NASA's Mars Orbiter Laser Altimeter helps tell the ancient story of how Olympus Mons's lower flanks catastrophically collapsed several 100 million years ago. ESA scientists say that large amounts of lava once flowed down the volcano, triggering landslides that tumbled down its flanks to meet bedrock – in this case, bedrock containing ice and water.

The steaming hot lava caused the ice to melt and become unstable; as a result, the rocky rim of Olympus Mons broke off and partially slid away. This collapse came in the form of huge rockfalls and landslides, which slipped downwards and spread widely across the surrounding plains. As the landslides traveled across the landscape, they crumpled and pulled apart, created a wrinkly-looking surface. Later, fierce Martian winds whipped across the hardened lava flows and sculpted them into the softened wrinkles we see today in Lycus Sulci.

Scientists also see these features on Earth, although not as gigantic and widespread as on Mars. Comparable but smaller landslides can be seen around the volcanic islands of Hawaii and the Canary Islands, which have seen large rockfalls in the past.

Mars Express has been sending us dramatic images of Mars since 2003. In addition to the images, it also maps minerals, identifies the composition and circulation of its tenuous atmosphere, and explores how various phenomena interact in the Martian environment.

Source: ESA

Nancy Atkinson

Nancy Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com