The real cause of two Martian earthquakes

On December 24, 2021, NASA’s InSight lander recorded ripples due to a large earthquake with a distinctive signature across the surface of Mars. That was one of the largest earthquakes observed on the Red Planet. Now, through a couple of studies, some researchers show the true cause of this and another earthquake detected months ago in the same year.

Both earthquakes were not caused by phenomena originating in the interior of Mars but by the impact of meteorites.

The authors of the studies have used the surface waves produced by the collisions to reveal some more details of the structure of the Martian crust.

The structure of a planet’s crust and mantle can provide important information about its origin and evolution. Seismic waves that propagate along a planet’s surface, known as surface waves, can be used to map these structural features.

However, to date, these waves had not been detected on any planet outside of Earth.

While seismic tremors and meteorite impacts on the Red Planet are not uncommon, their detection and characterization have been difficult.

However, the two seismic events that happened during 2021 were exceptionally large.

The crater formed on December 24, 2021 by the impact of a meteorite in the Martian region of Amazonis Planitia. Large blocks of water ice can be seen around the rim of the crater. (Photo: NASA JPL / Caltech / University of Arizona)

In a study, Liliya Posiolova, from the company MSSS (Malin Space Science Systems), and her colleagues use images of the Martian surface taken from the space probe MRO (Mars Reconnaissance Orbiter), in orbit around Mars since 2006, and show that these two earthquakes were caused by meteorite impacts. These collisions, which generated two large impact craters (over 130 meters in diameter), sent surface waves that reverberated across the planet.

In the second study, Doyeon Kim of the Swiss Federal Institute of Technology in Zurich (ETH) and colleagues took advantage of these surface waves, the first detected on Mars, to better understand the interior structure of the planet under the InSight lander. Kim’s team found that the crust at this point is denser than previously inferred. These variations constrain models regarding the composition, formation, and thickness of the Martian crust. (Source: AAAS)