47 Mars quakes shook volcanic region
Computer analysis indicates streams of hot rock in the Martian subsurface. The surprisingly strong activity raises questions. Not least, why the planet has no magnetic field.
hot rock. This is indicated by a total of 47 possible Mars quakes that 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 Mars lander InSight. As the two researchers report in Nature Communications, most of the new quakes resemble two tremors already recorded in 2019 in the Cerberus Fossae region, one of the youngest tectonic structures on Mars. According to Tkalčić and Sun, the tremors trace back to flows of hot, plastically deformable rock in the Martian mantle. This would suggest that the planet's interior is far more active than previously suspected.
Previously, experts detected more than 400 Mars quakes in the InSight lander's data. Most of them, however, were minor tremors in the upper Martian crust or even near-surface stress cracks caused by temperature differences. More interesting are the few quakes that could be due to tectonic processes - in particular S0173a and S0235b, the relatively significant shaking 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 took another look at the InSight data to detect more quakes. The data contains a lot of interfering 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 Cerberus Fossae quakes, whose onset and onset of primary and secondary waves were identifiable 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 revealed no correlation with external rhythms such as the changing attraction by Mars' small moons. "We can therefore assume that the movement of molten rock in the Martian mantle was the trigger for the 47 new quakes beneath Cerberus Fossae," Tkalčić said, according to an Australian National University news release. The large number of quakes in the study period of only about a year suggest that significant movement is taking place in the subsurface. This raises further questions - including the lack of a magnetic field on Mars. After all, movements in the mantle would indicate convection currents, which in turn could generate a magnetic field.
Spectrum of Science
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