Marsquake traced to active fault deep beneath Valles Marineris, study finds
Researchers say a 2021 quake recorded by NASA's InSight lander came from ancient faults slipping beneath Mars' largest canyon system.
Faults beneath Valles Marineris, the largest canyon system in the solar system, are still active, according to a study published in Nature Communications and reported by Universe Today and The Daily Galaxy.
Researchers from Imperial College London and Columbia University studied a marsquake called S0976a. NASA's InSight lander recorded it on August 25, 2021. Both outlets report that the quake started on the opposite side of Mars from the lander. Universe Today describes it as the only marsquake detected in the planet's western hemisphere. The Daily Galaxy says it was the only one in that hemisphere that researchers could locate.
Earlier studies had placed the quake near western Valles Marineris, but its cause was unclear. Universe Today reported that the team's models of meteoroid impacts and landslides could not reproduce the recorded seismic waves. Satellite images from NASA's Mars Reconnaissance Orbiter also showed no new crater or landslide. The best fit was a strike-slip quake, in which blocks of crust slide sideways past each other, about 20 to 40 km beneath the valley.
“What makes the result compelling is that several completely different types of evidence point in the same direction.”Jung-Hun Song, lead author, Imperial College London
The finding matters because Mars has no moving tectonic plates. Both outlets say scientists had long questioned whether its ancient faults could still move. According to the outlets, the results suggest faults formed billions of years ago remain weak enough to slip under present-day stresses from long-term cooling, the Tharsis volcanic region and local conditions around the canyon.
"It shows that on a planet without plate tectonics, structures created billions of years ago can remain important and still control where the crust breaks today," co-author Folarin Kolawole of Columbia's Lamont-Doherty Earth Observatory told The Daily Galaxy.
Both outlets say the result adds Valles Marineris to other active areas on Mars, including Cerberus Fossae and southern Elysium Planitia. Because faulting differs between these places, stress in the Martian crust does not appear to follow a single planet-wide pattern.
The two reports agree on the main findings but differ on some details. Universe Today compares the canyon with Earth's Yarlung Tsangpo Grand Canyon, while The Daily Galaxy compares it with the Grand Canyon. Universe Today names the University of Illinois Urbana-Champaign as a contributor, while The Daily Galaxy quotes a Columbia co-author not mentioned by Universe Today. Both say the canyon is about 3,900 km long and up to 600 km wide.
Several questions remain open. Neither outlet reports how strong the quake was, how often the fault might slip, or whether more quakes are expected beneath the canyon. InSight cannot record new events. The mission ended in 2022, The Daily Galaxy reported, and Universe Today said dust on the lander's solar panels ended it. Song said the method could help researchers look for seismic activity on other planetary bodies thought to be inactive.
