Ancient Martian Megaflood from Valles Marineris May Have Raised Seas by 34 Metres

A colossal flood that once tore through Valles Marineris — the largest canyon system in the solar system — may have released enough water to raise the level of an ancient Martian ocean by roughly 34 metres, according to a new study published in the peer-reviewed journal Icarus.

The research estimates the event discharged approximately 1,245 trillion cubic metres of water. This volume, if spread across the planet, would have significantly boosted the global mean level of the hypothesised ocean that may have existed on early Mars.

Valles Marineris, a vast rift system stretching thousands of kilometres along the Martian equator, is thought to have been carved by catastrophic flooding in the planet's distant past. The new findings add weight to the idea that Mars once harboured large bodies of surface water, with sudden, dramatic releases from canyon systems playing a key role in shaping its hydrological history.

While the existence of an ancient Martian ocean remains debated, the study provides fresh quantitative insight into the scale of water movement on the Red Planet, offering clues about its ancient climate and potential habitability.