Hydrodynamics of impact-induced tsunami over the Martian ocean

Large bodies of liquid water ranging from lakes to oceans have been hypothesized to have occupied the surface of ancient Mars episodically. Such inferences have been founded largely on geomorphological observations of putative shoreline features during the period ranging from the 1980s to the early 2000s. High-resolution satellite images obtained during various Mars missions conducted since the early 2000s have enabled detailed sedimentological studies. One phenomenon that might leave sedimentological traces of the purported Martian paleo-oceans is a bolide impact and consequent generation of large tsunami waves. Numerical modeling of impact-induced tsunami waves on a hypothesized northern plains paleo-ocean was performed to elucidate their potential propagation characteristics on Mars, including the ranges of wave height and velocity. When considering a tsunami triggered by a 50 km-diameter impact cratering event, the offshore and shore-zone wave heights respectively reached 40–50 m and 120 m. In the same test scenario, the tsunami wave velocity reached 20 m/s near the crater and 16 m/s at the shore zone. The wave height and velocity in highly cratered regions, such as Arabia Terra, tend to be relatively low because tsunami inundation is diffused by impact crater rims existing along the tsunami passage.