Mars experienced widespread volcanism and tectonic activity 3 to 4 billion years ago, but it has been viewed as largely tectonically quiescent since then. From 2018 to 2022, NASA’s InSight lander monitored seismic activity on the Red Planet, discovering a surprising number of strong marsquakes at Cerberus Fossae within Elysium Planitia, a lowland plains area. Elysium features the most recent volcanic activity on Mars, with large eruptions occurring over the past 200 million years. Cerberus itself is the site of a small eruption that occurred 53,000 years ago.

Adrien Broquet and Jeff Andrews-Hanna at the University of Arizona Lunar and Planetary Laboratory propose that a mantle plume — a hot mass of buoyant rock that upwells from deep in a planet and pushes through the mantle to the base of the crust — could explain this seismic activity and conducted a geophysical study of Elysium Planitia to test their hypothesis. Most recent tectonic features on Mars, such as wrinkle ridges, are due to compressional forces associated with planetary cooling, but the authors note that Cerberus Fossae is formed by extensional fissures that cross-cut the wrinkle ridges, indicating a very recent transition in stress regime. By analyzing topography and gravity data, they found that the surface of Elysium Planitia was uplifted 1-2 kilometers and that the uplift is supported from deep within the planet. A survey of impact crater floors, which are assumed to have originally been horizontal, found that they are all tilted away from the center of the proposed plume located southeast of Elysium Mons. Numerical modeling suggests that the plume head would be 4000 kilometers wide.

The authors argue that an active mantle plume is the only explanation accounting for all these observations. Such a plume indicates that Mars is much more geodynamically active today than previously thought. This result shifts our understanding of martian geological evolution. READ MORE