What could be hiding under the earthquakes found on Mars

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[EN VIDÉO] Mars InSight: a geophysicist on Mars
Launched in May 2018 and installed on Mars in November, the InSight lander is set to explore the Red Planet’s least known environment: its basement, all the way to its core. Thanks to sophisticated instruments, including a seismometer and a five-meter drill, this is enough to help us better understand our little neighbor.

The Red Planet, like the Earth, has been the site of violent tectonic activity, as evidenced by some of the rugged structures on its surface, such as Valles Marineris, a vast network of canyons stretching nearly 4,000 kilometers. Mars is still seismically active today. From arrivalIn sight in the region ofElysium Plain November 26, 2018 and deployment of the seismometer seisfirst direct observation of earthquakes The Martians were created. epicenters the most aggressive were in the area of ​​the city. Cerberus Fossecharacterized by a series of faults more than 1000 kilometers long, formed less than 20 million years ago and sheltering volcanic activity that is still quite recent (less than 200,000 years).

Noise problem in seismic data analysis

But due to the relatively small martian earthquakes and potentially high levels of noise, detection and definite identification of these shocks is not easy. Team of scientists Thus, China and Australia have developed two new models for seismic data analysis, allowing them to detect low-magnitude earthquakes previously drowned in ambient noise. Their new analysis methods then identified 47 new repetitive and relatively similar seismic events in the data collected by Seis, likely located in nearby regions, around Cerberus Fosseand associated with two previously detected earthquakes.

A new suspect in the explanation of the Martian earthquakes?

Prior to the discovery of these 47 new seismic events, there were already many hypotheses regarding the events that led to the occurrence of Martian earthquakes: some earthquakes detected during the Martian night, according to scientists, will be caused by the cooling and contraction of the planet. ; others argue that the interaction between Mars and its two moons, Phobos and Deimoscould also cause earthquakes due to tidal effects – just like the gravitational pull exerted by the Earth on moon generates moonquakes.

But the detection of these new earthquakes, observed day and night, does not appear to be related to the movement of the planet’s two satellites, which rules out these two hypotheses to explain their origin. The great depth of their epicenters, apparently, also excludes a possible tectonic origin along normal faults. Cerberus Fosse.

Then the scientists decided to reason by drawing analogies with our planet: on Earth, the vast majority of earthquakes are distributed along the boundaries between tectonic plateswhile a small part – about 10% – of the Earth’s earthquakes originate inside the plates lithospheric. Mars, on the other hand, does not have active tectonic plates: thus, since the Red Planet has only one plate, we can compare Martian earthquakes to terrestrial earthquakes within lithospheric plates.

On the Earth, if earthquakes within the plates are not caused by fault movement, their origin is usually attributed to volcanic events or to the movement of underlying fluids. Combining these comparisons with recent volcanic structures Cerberus Fossescientists tend to think that volcanic activity could be the cause of these recently analyzed earthquakes; however, on Earth, volcanic earthquakes usually result in volcanic eruptions, while these new earthquakes were not accompanied by any eruptions. The team attributes the lack of eruptions associated with these earthquakes to, in part, the large thickness crustprevention wash get to the surface. According to scientists, the number of repeated earthquakes detected day and night will be a sign of movements in the bowels of Mars, and seismic activity detected around Cerberus Fosse will be caused by the movement of molten rock into Coat a superior Martian, who in this case would be more active than previously thought.

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