New Impacts on Mars: Unraveling Seismic Propagation Paths Through a Cerberus Fossae Impact Detection

Abstract

To date, eight meteoroid impacts have been identified in the seismic record of NASA's InSight mission on Mars, occurring either within 300 km or beyond 3,500 km. We report the association of a high-frequency marsquake, S0794a, with a new 21.5-m-diameter impact crater discovered at an intermediate distance of 1,640 km in the tectonically active Cerberus-Fossae graben system. This impact enables the direct comparison between surface and subsurface sources, as well as providing the first data point in the critical gap between previous impacts, both in distance and crater size. Additionally, the location of this event necessitates a reassessment of assumed seismic raypaths that were thought to propagate along a slow crustal waveguide. We find that the raypaths instead penetrate and travel through the faster mantle, implying numerous identified marsquake epicenters should be relocated up to two times farther from InSight, with implications for seismically derived impact rates and regional seismicity.