NEW DELHI: The marsquake of May 2022 was caused by the release of enormous tectonic forces within Mars' interior, suggesting that the planet might be more seismically active than previously thought, researchers say.
The quake with a magnitude of 4.7 and causing vibrations to reverberate through the planet for at least six hours had been recorded by US's NASA's InSight lander on May 4.
Because its seismic signal was similar to previous quakes known to be caused by meteoroid impacts, the team from the University of Oxford, UK, had initially believed that this event (dubbed 'S1222a') might have been caused by an impact as well.
Hence, they had launched an international search for a fresh crater, the researchers said.
Studying InSight's observations made during its time on Mars, they found that the largest two of the eight marsquake events recorded by the lander formed craters around 150m in diameter.
All these events were caused by meteoroid impacts.
If the S1222a event was formed by an impact, the crater would be expected to be at least 300m in diameter, the researchers hypothesised.
However, after several months of surveying the Martian land surface, the team announced today that no fresh crater was found.
They thus concluded that the largest marsquake was instead caused by release of seismic energy, indicating seismic activity within the planet's interior than previously thought, they said in their study published in the journal Geophysical Review Letters.
For the survey of the Martian land, which is about 144 million square kilometres in area, the study lead Benjamin Fernando from Oxford's Department of Physics sought contributions from global space agencies, including the Indian Space Research Organisation (ISRO).
The European Space Agency and the Chinese National Space Agency also contributed.
"We still think that Mars doesn't have any active plate tectonics today, so this event was likely caused by the release of stress within Mars' crust. These stresses are the result of billions of years of evolution; including the cooling and shrinking of different parts of the planet at different rates. We still do not fully understand why some parts of the planet seem to have higher stresses than others, but results like these help us to investigate further," said Fernando.
"This experiment shows how important it is to maintain a diverse set of instruments at Mars, and we are very glad to have played our part in completing the multi-instrumental and international approach of this study," said Daniela Tirsch, Science Coordinator for the High Resolution Stereo Camera on board the European Space Agency's Mars Express Spacecraft.