Evidence of two tsunami events on Mars, possibly triggered by meteor impacts, is presented in a study in Scientific Reports this week. The results suggest that tsunamis may have played a role in generating and resurfacing coastal terrain on early Mars.

It has been proposed that approximately 3.4 billion years ago enormous floods created an ocean which covered most of the Martian northern lowlands. However, a lack of definitive shoreline features on the surface of Mars has meant that is difficult to verify this hypothesis.

Based on geomorphic and thermal image mapping of the circum-Chryse and north-western Arabia Terra regions of the northern plains of Mars, in combination with numerical analyses, Alexis Rodriguez and colleagues argue that tsunamis may have played a part in reshaping the early Martian landscape. Numerical analyses carried out by the authors suggest that meteor impacts, causing craters approximately 30 kilometres in diameter, would have generated tsunami waves with typical onshore heights of approximately 50 metres. The authors found that within the early Martian ocean, impact craters of this size were formed every three million years during the Late Hesperian Epoch (approximately 3.4 billion years ago).

The authors note that although they have identified evidence for two tsunami events in the study area, other regions in the northern plains likely experienced similar tsunami-related coastal resurfacing, perhaps associated with other impacts, huge landslides or large Martian earthquakes.