The discovery, based on more than 1,000 earthquakes, suggests that the planet is not geologically dead.
|In this 2018 image taken by the Mars Express orbiter, a relatively young fracture cuts through hills and craters in Mars' heavily faulted Cerberus Fossae region. DLR, ESA, and FU BERLIN (CC BY-SA 3.0 IGO)
Mars may still be alive, geologically speaking.
Researchers have examined a slew of recent Marsquakes and determined that they are most likely caused by magma moving deep beneath the Martian surface. The researchers report in Nature Astronomy on October 27 that this is evidence that Mars is still volcanically active.
NASA's InSight lander has detected over 1,000 Marsquakes since landing on Mars four years ago (SN: 11/26/18). Its seismometer records seismic waves, which reveal information about the size and location of a temblor.
Previous research has determined that several Marsquakes originated from the Cerberus Fossae swath of Martian terrain (SN: 5/13/22). This region, which is particularly faulted, is over 1,000 kilometers away from the InSight lander.
However, according to Anna Mittelholz, a planetary scientist at Harvard University, most of the Marsquakes linked to Cerberus Fossae have been fairly familiar scientifically. Their low-frequency seismic waves "look much more like what we see for an earthquake," she claims.
Mittelholz and her colleagues have now studied a large number of Marsquakes, including over 1,000 high-frequency temblors that look nothing like their terrestrial counterparts. The researchers combined their relatively weak signals to better understand the origin of the high-frequency quakes. The researchers observed a peak in the amount of seismic energy coming from the direction of Cerberus Fossae in that stack of seismic waves. Hrvoje Tkali, a geophysicist at the Australian National University in Canberra who was not involved in the research, says it was an impressive undertaking. "No previous study attempted to locate the high-frequency quakes."
It's surprising that different types of Marsquakes are all concentrated in one area. Previous research suggested that Marsquakes could be caused by the planet's surface cooling and shrinking over time. According to Mittelholz (SN: 5/13/19), that process, which occurs on the moon, would result in temblors evenly distributed across the planet. "It was expected that Marsquakes would come from all over the place."
The researchers also demonstrated that the low-frequency Marsquakes are most likely caused by magma moving several tens of kilometers beneath Mars' surface by comparing the seismic waves measured by InSight with seismic waves produced in different regions of our own planet. "Our findings are much more consistent with data from Earth's volcanic regions," Mittelholz says.
The researchers conclude that, rather than being a geologically dead planet, Mars may be a surprisingly dynamic place. According to Mittelholz, this discovery rewrites our understanding of Mars, and there is still so much more to learn about our celestial neighbor. "We're just getting started."
S.C. Stähler and colleagues Earthquakes reveal the tectonics of Cerberus Fossae. Astronomy in nature. On the internet on October 27, 2022. doi: 10.1038/s41550-022-01803-y.