When NASA announced that water had been found flowing on the surface of Mars, Inverse was naturally quite excited. After the announcement, new questions began to develop about the shitory behind Mars’s water, particularly involving craters that some scientists believed had once been part of the planets oceans.

Now, a team of Mars researchers from the Planetary Science Institute in Tucson, Arizona have discovered evidence of at least two powerful tsunamis, which they believe may have impacted the level of Mars’s ocean shorelines. The tsunami — described as being taller than skyscrapers and thousands of miles wide — could have made enough of an impact to the surface of the planet that might cause such a devastating change. On the scale of planetary catastrophes, such tsunamis would have dwarfed most Earthly ones. Alexis Rodriguez, who led the team, set up the image of the tsunamis: “Imagine this enormous red wave coming towards you, up to 120 meters high. It would have been pretty spectacular.”

The research will help confirm — or, at least, clear up — a long-held assertion that Mars once had an ancient Northern ocean. The theory may be partially correct, but the team discovered something even more interesting during their study: The shoreline may be buried beneath the devastation of a tsunami caused by meteors. “We were trying to find shorelines on Mars like those we typically see on Earth, which is consistently distributed along a constant elevation,” Rodriguez explained. “And that is not what we have found on Mars, because in the case of Mars the shorelines were buried beneath the tsunami deposits.”

The team used satellite images to identify thick deposits of boulders and silt that they say were left behind by the impact of two separate tsunamis that occurred a few million years apart, roughly three and a half-billion years ago. For their study, the team focused on a region of highlands on Mars that are known as Arabia Terra, zeroing in on an area where they bump up against the lowlands of Chryse Planitia. There, the ancient ocean was believed to brush up against the shoreline.

The team is now looking for evidence of tsunamis in other regions, including a small group of craters near the shoreline that could have been drenched by the tsunami, and could have potentially trapped that water for millions of years.

Photos via Earth and Planetary Science Letters