Earthquakes on Mars indicate the presence of magma beneath the surface

Earthquakes on Mars indicate the presence of magma beneath the surface

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NASA’s InSight mission has been measuring seismicity on Mars for nearly four years. His goal? Determine the internal structure of the planet to shed light on the processes of formation and evolution of the terrestrial planets of the Solar System. The latest seismic data collected by the scientists seems to indicate the presence of a hot spring at depths of 30 to 50 kilometers, which is compatible with recent magmatic activity.

By examining how seismic waves generated by earthquakes or meteor impacts propagate inside Mars, scientists are able to pinpoint its internal structure, from the crust to the core. From the beginning the InSight missionOn November 26, 2018, more than 1,300 aftershocks were recorded with magnitudes between 1 and 4. a tectonic gap caused by the collapse of two faults) involving a series of seismic cracks located approximately 1,600 km from the probe’s landing site.

Experts believe that Mars was very volcanically active in the past, but the planet remained relatively quiet for several million years and is now “geologically dead”. Based on the data transmitted by InSight, an international team of researchers led by ETH Zurich studied about twenty recent Martian seismic events: their analyzes indicate the presence of a probable magma deposit near the Cerberus pits – which would explain why many of the recorded earthquakes originate from this area.

Evidence of relatively recent volcanic activity

[Les données montrent] that the most widespread surface faults are not seismically active and that the seismicity comes mainly from a single population of tectonic structures, the Fosses of Cerberus “, the researchers write Astronomy of nature. By analyzing the spectral characteristics of the seismic waves, they found that they were essentially low in frequency—a characteristic usually associated with volcanic conditions.

Topographic view showing the relative heights of the Cerberus Fossae features: the red and white areas are relatively higher than the blue areas. © ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

The team concluded that there must be some kind of hot body or magma chamber in this area, which means the planet may still be geologically active and that this activity still plays a role in shaping the surface of Mars. They found that the earthquakes were mostly in the innermost part of Cerberus Fossae. The epicenters were all located near a structure previously described as a “young volcanic rift”.

Their findings were confirmed by satellite images showing dark deposits around this fissure, likely dust, evidence of relatively recent volcanic activity. ” The darker shade of dust is geological evidence of more recent volcanic activity – perhaps within the last 50,000 years – which is relatively young in geological terms. », explains Simon Stählerseismologist at ETH Zurich and first author of the study.

dust volcanic activity
Zunil Crater (in yellow rectangle) shows dust deposits in the direction of the prevailing wind. Cerberus pits (yellow oval) show darker dust deposits in several directions, suggesting more recent volcanic activity, the researchers said. © Emirates Mars Mission EXI Camera

High-frequency earthquakes have been detected elsewhere along the Cerberus Pits – in a more fragile and shallow area, potentially in fault planes associated with graben flanks. ” Together, these earthquakes release an annual seismic moment of 1.4 to 5.6 × 1015 N m per year, or at least half of the seismicity of the entire planet ” says the team.

Pits shaped by magmatic processes

The study of geological processes on Mars is important for a better understanding of similar processes occurring on Earth. Mars is not only our nearest neighbor, but also the only one (to our knowledge) that has a core of iron, nickel and sulfur and that would have been endowed with a magnetic field in the past. In addition, there is increasing evidence that this planet once had vast volumes of liquid water, along with a much denser atmosphere than today.

In short, Mars has (or had) several things in common with Earth. Instruments sent to its surface (rovers, helicopters, seismometers) make it possible to obtain much more complete and accurate data than orbital exploration allows. But the combination of all these data offers reliable insight into the red planet’s past and present. ” While there is still much to learn, the evidence for potential magma on Mars is intriguing said Anna Mittelholz, a postdoctoral researcher at ETH Zurich and Harvard University and co-author of the study.

The desert planet we know today was much more active about 3.6 billion years ago, as evidenced by the planet’s impressive volcanic remains: the Tharsis Montes region, the largest chain volcano known in our solar system, and Olympus Mons, a volcano whose high the height is almost three times the height of Mount Everest!

Previous research into the Cerberus pits suggested that the area had been still volcanically active for the past 10 million years. The results of this new study suggest that Mars is not quite dead yet. According to Stähler, it is possible that the pits are one of the last remnants of this once active volcanic region. The data also suggest that the dynamical process may continue to propagate eastward.

source: S. Stähler et al., Nature Astronomy

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