NASA's InSight lander was previously deployed on Mars (now decommissioned due to power outages) to listen for seismic activity on Mars. Last year it detected a Martian earthquake with a large magnitude and was suspected to be caused by a meteoroid impact. Now, thanks to the cooperation of all agencies with Mars orbiters, the source of the earthquake has been traced.
On May 4, 2022, InSight detected a Martian earthquake with a magnitude of 4.7 - the strongest earthquake ever recorded on Mars. The quake, named S1222a, was five times more powerful than the next strongest earthquake and released as much energy as all the other Martian quakes it had detected in its five-year lifetime combined.
Mars doesn't have any active plate tectonics, so it's thought to be incapable of producing earthquakes of such magnitude. Therefore, scientists suspect that S1222a is the result of a meteoroid impacting the Martian surface, which often produces similar seismic waves. Based on its power, such an impact would have produced at least a 300-meter (984-foot) wide crater—so to put that question to rest, we scoured the entire planet for any new craters of the same size or larger.
A project of this magnitude requires the cooperation of every agency operating a Mars orbiter - NASA, ESA, CNSA, ISRO and UAESA. Each team investigated satellite data, looking for new craters that appeared after the earthquake or other evidence such as dust clouds found in the hours after the earthquake.
They spent several months searching, but ultimately found no such crater. The team has now concluded that the earthquakes must be caused by tectonic forces within the Red Planet's interior, suggesting it is a more seismically active world than previously thought.
Dr. Benjamin Fernando, the first author of the study, said: "We still believe that Mars currently does not have any active plate tectonics, so this earthquake is likely to be caused by the release of stress within the Martian crust. These stresses are the result of billions of years of evolution, including different parts of the Earth. Cooling and shrinking at different rates. We still don't fully understand why some places on Earth seem to be more stressed than others, but results like this can help us further study. One day, this information may help us understand which places are safe for humans to live on Mars and which places may be avoided!"
After detecting S1222a, InSight will rest on Mars in December 2022. At least now it can sleep peacefully knowing it has contributed some fascinating new information to Mars.
The research was published in the journal Geophysical Research Letters.