Nature goes EXXXTREEEEME!!! in the search for evidence of water on Mars. And boy did they find evidence. Seems like a couple billion years ago, meteorite impacts unleashed cosmic-sized tsunamis across the Red Planet:
Some 3.4 billion years ago, giant meteoroids slammed into a frigid ocean covering Mars’s northern hemisphere. The impacts kicked up enormous waves that raced across the water and swamped the shoreline, research suggests.
…
“Imagine this enormous red wave coming towards you, up to 120 metres high,” says Alexis Rodriguez, a Mars researcher at the Planetary Science Institute in Tucson, Arizona. “It would have been pretty spectacular.”
Rodriguez and his colleagues mapped traces of two of these tsunamis. They describe the findings in Scientific Reports.
…
Rodriguez began thinking about Martian tsunamis after visiting the eastern coast of Japan in 2011, which had been devastated by a tsunami generated by a magnitude-9 earthquake. His team grew to include some top Martian geology experts.
The group zeroed in on a region on Mars where the highlands known as Arabia Terra bump up against the lowlands of Chryse Planitia — a place where the waters of an ancient ocean might have lapped at the shoreline. Using imagery from several Mars-orbiting spacecraft, Rodriguez’s group identified two particular geological formations that they say formed during two different tsunamis.
Photos at the link.