What Triggers These Martian Avalanches?

By cross-referencing data collected by the SEIS seismometer as part of the InSight mission on Mars and available orbital data, a scientific team has revealed that Martian seismic activity can be responsible for dust avalanches.


Thanks to a detailed analysis of both orbital and seismological data from the two most significant seismic events recorded during the InSight mission on Mars (operational from late 2018 to late 2022), a team of researchers from IPGP (Paris Cité University / CNRS) and their colleagues have highlighted a clear increase in the number of dust avalanches around the two epicenters.

The first studied event, named S1000a, is a meteoritic impact that occurred on September 18, 2021, generating an earthquake with a local Martian magnitude of 4.1 and forming a crater approximately 492 feet in diameter. The comparison of orbital images before and after this event shows a significant amount of new dust avalanches around the epicenter, within a radius of about 12.4 miles, generated by a strong surface acceleration.


The second event, named S1222a, occurred on May 4, 2022, and constitutes the largest earthquake ever detected on Mars, with a magnitude of 4.7. Located near the Apollinaris volcano, close to the Martian crustal dichotomy, its epicenter is probably located at a depth of less than 12.4 miles, though its energy is about 25 times greater than that of the S1000a earthquake. By comparing the study of all available orbital data of the Red Planet since 2005 with the high-resolution orbital images of this second earthquake, researchers observed that the avalanche rate increased from 3% (meaning that for every 100 existing avalanches, 3 new ones appear over a Martian year, or 687 Earth days) to 40% after the earthquake for some areas.

The causal link between this earthquake and the triggering of avalanches appears even clearer as, on one hand, no storm occurred during the period covered by the images before and after the earthquake, and on the other hand, the slopes on which these avalanches formed show no preferential orientation, not even that of the prevailing south-north winds recorded in this area.


Armed with this result, scientists then sought to refine the localization of the epicenter of the S1222a seismic event, based on certain laws used on Earth that interpret the distribution of landslides and avalanches in relation to the epicenters of the earthquakes that triggered them. The position thus obtained allows researchers two different interpretations regarding the mechanism at the origin of the earthquake. The first theory suggests that seismic activity could be related to an ancient volcano, Apollinaris Patera, although it is unlikely to still be active. The second hypothesis suggests that a large geological structure might be the origin of the earthquake, a ridge about 280 miles long located right next to the obtained epicentral position.

This work paves the way for future research, especially to better understand how Martian seismic activity can influence surface and subsurface processes. Moreover, this study shows that analyzing surface processes can help us gain a better understanding of the mechanisms behind the current seismicity of the Red Planet.

References:


A. Lucas, I.J. Daubar, M. Le Teuff, C. Perrin, T. Kawamura, L. Posiolova, P. Lognonné, S. Rodriguez, D. Giardini, G. Sainton, A. Mangeney, A. McEwen, Possibly seismically triggered avalanches after the S1222a Marsquake and S1000a impact event, Icarus, Vol. 411, 2024, 115942, DOI: 10.1016/j.icarus.2023.115942.

Data set in the IPGP Research Collection: Lucas, Antoine; Daubar, J. Ingrid; Le Teuff, Manon; Perrin, Clément; Kawamura, Taichi; Posiolova, Liliya; Lognonné, Philippe; Rodriguez, Sébastien; Giardini, Domenico; Sainton, Grégory; Mangeney, Anne; McEwen, Alfred, 2024, "Avalanches catalogue associated to the s1222a Marsquake", https://doi.org/10.18715/IPGP.2024.lr68kbwy, IPGP Research Collection, V1.