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Marsquakes – another clue in the search for life on Mars

Scientists at Birkbeck, University of London have found compelling evidence that Mars...

Scientists at Birkbeck, University of London have found compelling evidence that Mars, Earth’s closest neighbour, experiences ‘marsquakes’ in the same way that the earth shakes during an earthquake. The existence of marsquakes, explained in a paper to be published in Journal of Geophysical Research Planets on Thursday (23 Feb) and highlighted in Nature Geosciences, is an indication that conditions on Mars could include liquid water, a resource thought to be a prerequisite for life on Mars.

The team used High Resolution Imaging Science Experiment (HiRISE) imagery to examine boulders along a fault system known as Cerberus Fossae, that cuts across a very young (few million years old) lava surface on Mars. By analysing the way boulders had fallen and rolled during avalanches, the team suggest that the avalanches are likely to have been caused by ground-shaking associated with marsquakes, rather than by temperature changes, another common cause of martian rock falls.

Dr Gerald Roberts, who led the study, said: “The HiRISE imagery showed us boulders in the size range of 2-20 metres, that had fallen from cliffs during rock avalanches. What’s more, both the size of the boulders and the frequency of the boulder falls decreased from a central point along the Cerberus Fossae fault system over a distance of approximately 100 kilometres. This is consistent with the hypothesis that boulders had been mobilised by ground-shaking, and that the severity of the ground-shaking decreased away from the epicentres of marsquakes.”

The team compared the pattern of the boulder falls, and the faulting of the surface of Mars, with those seen in central Italy, after the 6.3 magnitude earthquake near L’Aquila, central Italy, in 2009, where boulder falls occurred up to approximately 50 km from the epicentre. This comparison shows that the marsquakes were likely to have had a magnitude greater than 7.0 due to the approximately 200 km-across area of displaced boulders.

By looking at the tracks that the falling boulders had left on the dust-covered martian surface, the team concluded that the marsquakes appear to be have been relatively recent – and certainly within the last few percent of the planet’s history – because martian winds had not yet erased the boulder tracks, even though it is well-known that tracks left by NASA robotic rovers are erased within a few years by martian winds. It is possible that large-magnitude marsquake activity is still occurring on Mars.

The discovery of marsquakes would be significant in the ongoing search for life on Mars because if the faults along the Cerberus Fossae region are active, and the quakes are driven by subterranean volcanism related to the nearby volcano, Elysium Mons, the energy provided in the form of heat from the igneous dikes might melt ice, creating liquid water, and thus providing habitats that might support life.

Dr Roberts explains: “It is this link between life, volcanism and active faulting that makes the boulder data we have collected so intriguing.”

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