The finding, based on more than 1,000 quakes, suggests the planet isn’t geologically dead
Researchers have analyzed a slew of recent temblors on the Red Planet and shown that these Marsquakes are probably caused by magma moving deep under the Martian surface. That’s evidence that Mars is still volcanically active, the researchers report October 27 in Nature Astronomy.
Since touching down on Mars four years ago, NASA’s InSight lander has detected more than 1,000 Marsquakes. Its seismometer records seismic waves, which reveal information about a temblor’s size and location.
Previous studies have determined that several Marsquakes originated from a swath of Martian terrain known as Cerberus Fossae. This region, which is particularly riddled with faults, is more than 1,000 kilometers from the InSight lander.
But most of the Marsquakes linked to Cerberus Fossae so far have been pretty familiar, scientifically speaking, says Anna Mittelholz, a planetary scientist at Harvard University. Their seismic waves, which are low frequency, “are ones that look much more like what we see for an earthquake,” she says.
Mittelholz and her colleagues have now analyzed a large sample of Marsquakes, including more than 1,000 high-frequency temblors, which look nothing like their earthly brethren. To better understand the origin of the high-frequency quakes, the researchers added together their relatively weak signals. In that stack of seismic waves, the researchers saw a peak in the amount of seismic energy coming from the direction of Cerberus Fossae. That was an impressive undertaking, says Hrvoje Tkalčić, a geophysicist at the Australian National University in Canberra who was not involved with the research. “No study before this one attempted to locate the high-frequency quakes.”
The fact that different types of Marsquakes are all concentrated in one region is a surprise. Previous research has suggested that Marsquakes might be due to Mars’ surface cooling and shrinking over time. That process, which occurs on the moon, would produce temblors evenly spread over the planet, Mittelholz says (SN: 5/13/19). “The expectation was that Marsquakes would originate from all over the place.”
And by comparing the seismic waves that InSight measured with the seismic waves produced in different regions on our own planet, the researchers further showed that the low-frequency Marsquakes are probably produced by magma moving several tens of kilometers below Mars’ surface. “Our results are much more consistent with data from volcanic regions on Earth,” Mittelholz says.
Rather than being a geologically dead planet, as some have suggested, Mars might be a surprisingly dynamic place, the researchers conclude. This finding rewrites our understanding of Mars, Mittelholz says, and there’s still so much more to learn about our celestial neighbor. “We’re only scratching the surface.”