Under a presumably active volcanic region on Mars, hot rock is still moving today. This is pointed out by a total of 47 possible Marsquakes, which Weijia Sun from the Chinese Academy of Sciences in Beijing and Hrvoje Tkalčić from the Australian National University in Canberra found in the data of the Marlanders Insight. As the two researchers report in »Nature Communications«, most new quakes are similar to two shocks already registered in 2019 in the Cerberus Fossae region, one of the latest tectonic structures on Mars. According to Tkalčić and Sun, the vibrations go back to currents of hot, plastically deformable rock in the Mars coat. This would indicate that the interior of the planet is far more active than previously suspected.
Previously, experts had discovered more than 400 marsquakes in the data of the InSight lander. Most of them, however, were minor tremors in the upper Martian crust or even near-surface stress cracks due to temperature differences. More interesting are the few quakes that could be due to tectonic processes – in particular S0173a and S0235b, which have relatively significant tremors in Cerberus Fossae with magnitudes between three and four. Experts interpreted these in 2019 as signs of active processes in the region, where there is also evidence of recent volcanic activity.
Tkalčić and Sun once again took the InSight data to track down further quakes. The data contains a lot of disturbing noise that overlays many signals. Therefore, the researchers used the waveforms of previously measured quakes as a template to identify weak signals – including the two quakes of the Cerberus Fossae, the onset and onset of the primary and secondary waves of which were recognizable in the data, which facilitated the analysis. In this way, they found 47 other possible quakes, most of them at low frequencies such as S0173a and S0235b.
A temporal analysis of the quakes showed no connection with external rhythms such as the changing attraction through the small moons of Mars. "We can therefore assume that the movement melted in the Mars coat was the trigger of the 47 new quakes under Cerberus Fossae," says Tkalčić, according to a press release from the Australian National University. The large number of quakes in the examination period of only around one year suggest that there are considerable movements in the subsoil. This raises further questions - among other things about the missing magnetic field of Mars. Because movements in the coat would indicate convection currents, which in turn could create a magnetic field.
