A massive earthquake that shook Mars in May this year was at least five times larger than the previous record holder, new research has revealed.
We don’t know what the source of the earthquake was, but it was really peculiar. As well as being the strongest earthquake recorded on Mars to date, it was also the longest by any significant amount, shaking the Red Planet for 10 hours.
“The energy released by this single Marchquake equals the cumulative energy of all other Marchquakes we have seen so far,” says seismologist John Clinton from the Swiss Federal Institute of Technology in Switzerland, “and even though the event was more than 2,000 kilometers (1,200 miles) away, the waves recorded at InSight were so large that they almost saturated our seismometer.”
The new analysis of the earthquake, published in Geophysical Research Letters, fixes its magnitude at 4.7. The previous record holder was a magnitude 4.2 earthquake detected in August 2021.
It might not look like a big earthquake by Earth standards, where the strongest earthquake ever recorded tipped a magnitude of about 9.5. But for a planet that was thought to be seismically inactive until NASA’s InSight probe began recording its interior in early 2019, it’s impressive.
Although Mars and Earth have a lot in common, there are some really key differences. Mars has no tectonic plates; nor does it have a coherent global magnetic field, often interpreted as a sign that not much is going on in the Martian interior, since Earth’s magnetic field is theorized to be the result of thermal convection internal.
InSight has revealed that Mars is not as seismically quiet as we previously assumed. It creaks and rumbles, alluding to volcanic activity under the Cerberus Fossae region where the InSight lander crouches, surveying the hidden innards of the planet.
But determining the activity status of the Martian interior is not the only reason to monitor earthquakes. The way seismic waves propagate through and through a planet’s surface can help reveal variations in density within. In other words, they can be used to rebuild the structure of the planet.
This is usually done here on earthbut hundreds of earthquakes recorded by InSight have allowed scientists to build a martian interior maptoo.
The May earthquake may have been just a seismic event, but it appears to have been a significant event.
“For the first time, we were able to identify surface waves, traveling along the crust and upper mantle, which circled the planet multiple times,” Clinton says.
In two other separate articles of Geophysical Research Lettersteams of scientists have analyzed these waves in an attempt to understand the structure of the crust on Mars, identifying regions of sedimentary rock and roll volcanic activity inside the crust.
But there is more to the earthquake itself. First, it originated in the Cerberus Fossae region, but not here, and could not be attributed to any obvious surface feature. This suggests it might be related to something hidden under the crust.
Second, March quakes are generally high or low in frequency, with the former being characterized by fast, short quakes, and the latter by longer, deeper waves with larger amplitudes. This earthquake combined both frequency ranges, and researchers aren’t sure why. However, it is possible that high and low frequency earthquakes previously recorded and analyzed separately could be two parts of the same seismic event.
It could mean scientists need to rethink how marsquakes are understood and analyzed, revealing even more secrets hidden beneath the deceptively quiet Martian surface.
“It was definitely the biggest earthquake we’ve seen,” says planetary scientist Taichi Kawamura from the Paris Globe Physics Institute in France.
“Stay tuned for more exciting stuff after this.”
The research has been published in Geophysical Research Letters.