This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Scientists at Columbia University and Imperial College London have found that the largest canyon system in the solar system is still active and shaping Mars today, billions of years after it first formed. New research presents direct seismic evidence that a marsquake (Mars's equivalent of an earthquake) detected by NASA's InSight lander originated beneath the vast Martian canyon system, Valles Marineris, and was caused by rocks slipping along a fault deep within the planet's crust.
The finding suggests that faults established during the formation and early evolution of Valles Marineris billions of years ago can remain weak enough to rupture under stresses acting on Mars today. "Valles Marineris is one of the most spectacular geological structures anywhere in the solar system, but until now we didn't know for certain that its faults are still active," said Jung-Hun Song, lead author of the study from Imperial's Department of Earth Science and Engineering. "What we see is that this is not just a 'dead' fossil landscape, as faults deep beneath the canyon can still slip and generate marsquakes, long after the geological processes that originally formed them have ceased.
"Our study opens up exciting possibilities for discovering ongoing seismic activity on other planetary bodies that we might otherwise consider geologically inactive." Valles Marineris is difficult to comprehend on an earthly scale. The vast canyon system stretches nearly 3,900 kilometers (2,400 miles) across Mars, reaches up to 600 kilometers (370 miles) wide and is more than 9 kilometers (5.6 miles) deep. That makes it nearly nine times longer, more than 20 times wider and about five times deeper than the Grand Canyon at their respective maximum dimensions, making it the largest canyon system in the solar system.
The researchers studied a seismic event known as S0976a, recorded by the InSight lander on Aug. 25, 2021. The event was unusual because it came from the opposite side of Mars from the lander and was the only marsquake detected during the mission that could be located in the planet's western hemisphere. Previous work had placed the event in the vicinity of western Valles Marineris, but its cause remained uncertain.
On Mars, a seismic signal doesn't necessarily mean that a fault has ruptured—meteoroid impacts, landslides and other processes can also send vibrations through the planet. To determine what produced S0976a, the researchers analyzed how different seismic waves from the event traveled through Mars and arrived at InSight. The study was published in Nature Communications.
From the amplitudes and directions of those waves, the team could reconstruct the type of motion that occurred at the source. The best explanation was a strike-slip marsquake, in which blocks of crust move horizontally past one another along a steep, deeply rooted fault. The rupture occurred roughly 20 to 40 kilometers (12 to 25 miles) beneath the surface of western Valles Marineris.
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