A tectonic origin for the largest Marsquake observed by InSight

Abstract

The S1222a marsquake detected by InSight on 4 May 2022 was the largest of the mission, at Mw^Ma 4.7. Given its resemblance to two other large seismic events (S1000a and S1094b), which were associated with the formation of fresh craters, we undertook a search for a fresh crater associated with S1222a. Such a crater would be expected to be ∼300 m in diameter and have a blast zone on the order of 180 km across. Orbital images were targeted and searched as part of an international, multi-mission effort. Comprehensive analysis of the area using low- and medium-resolution images reveals no relevant transient atmospheric phenomena and no fresh blast zone. High-resolution coverage of the epicentral area from most spacecraft are more limited, but no fresh crater or other evidence of a new impact have been identified in those images either. We thus conclude that the S1222a event was highly likely of tectonic origin.