Scientists investigate cause of largest ever Mars ‘quake’ – and find unexpected explanation

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Scientists have found the cause of the largest ever “quake” on the Martian surface – and an unexpected explanation.

Last year, Mars was hit by a quake that had a magnitude of 4.7 and meant that the red planet continued to shake for another six hours. It was first detected by Nasa’s InSight lander, which was sent in part to investigate such quakes.

Scientists initially thought the signal looked similar to meteoroid impacts, and so searched for signs of any crater it might have left. But they found that was not the cause.

Instead, the quake appears to have been the result of massive tectonic forces within Mars’s crust, the scientists say. That suggests that Mars is much more seismically active than we had realised.

“‘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,” said Benjamin Fernando from the University of Oxford, who led the study. “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. One day, this information may help us to understand where it would be safe for humans to live on Mars and where you might want to avoid!”

Mars is smaller than Earth but does not have any oceans, so actually has a similar amount of land surface area, at around 144 million km². That can make scanning it for signs of asteroid impacts – such as craters, or dust clouds – difficult.

To do that work, scientists from across the world – from the Chinese space agency to the one from the United Arab Emirates – collaborated to search all over the planet. Scientists believe it is the first time that all of the missions in orbit around Mars have worked together on one project.

But they could not find a crater. That led them to believe that the source of the quake was actually Mars itself, rather than something hitting it.

A study detailing the findings, ‘‘A tectonic origin for the largest marsquake observed by InSight’, is published today in Geophysical Research Letters.