The strongest recorded Marsquake was not due to an asteroid impact but due to tectonic forces within the planet itself. The earthquake was likely caused by the release of stress that had been building up for a billion years in the crust of Mars. Most likely, it happened because different parts of the planet cooled and contracted at different rates.
New results show that the Red Planet is more seismically active than previously thought. The scientific article was published in Geophysical Research Letters.
On May 4, 2022, NASA’s InSight probe detected a magnitude 4.7 marsquake, surpassing the previous 4.2 for 2021. Unusually for marsquakes, the aftershocks from this event lasted as long as six hours.
During its four years of operation, InSight recorded over 1,300 marsquakes. At least eight of them were caused by collisions with asteroids. A powerful pendulum motion in May 2022, recorded by a seismometer on board the probe, was reminiscent of those caused by asteroids. This prompted scientists to look for a new crater with a diameter of about 300 meters and a cloud of dust on Mars. However, nothing of the kind was found. For this reason, after a lengthy search, scientists concluded that the origin of this earthquake was tectonic.
It is generally accepted that, unlike Earth, tectonic processes have stopped on Mars. The Earth’s tectonic plates move due to forces in the mantle. The surface of Mars is much more monolithic, so it is believed that plate tectonics does not occur on the Red Planet.
Scientists still need to discover why some parts of the planet have higher voltages than others.
Banner image: This artist’s concept depicts NASA’s InSight lander after it has deployed its instruments on the Martian surface. Credit: NASA/JPL-Caltech