Constraints on the origin of the Martian dichotomy from the Southern Highlands marsquakes

Abstract The Martian hemispheric dichotomy presents a prominent elevation and crustal thickness contrast between the Northern Lowlands and Southern Highlands. The origin of dichotomy remains controversial, with several competing hypotheses proposed. However, analysis of InSight marsquakes offers the way forward. Here, we improve the signal-to-noise ratios and determine the locations of all significant low-frequency marsquakes. We find a new cluster of marsquakes in Terra Cimmeria of Southern Highlands, apart from those located previously in Cerberus Fossae of Northern Lowlands. We estimate the attenuation quality factor Q in the range 481–543 for Terra Cimmeria, which is considerably smaller than Q > 800 determined for Cerberus Fossae. We infer that a smaller Q might be linked to the warmer mantle and more vigorous convection beneath the Southern Highlands. These in situ seismological observations accompany the geochemical analysis of Martian meteorites supporting the “endogenic” hypothesis that mantle convection causes the crustal dichotomy. Teaser The analysis of the newly discovered marsquakes in Southern Highlands supports mantle convection as the main cause of Martian dichotomy.