Mars, 1.1 billion years ago. Sort of.
Four billion years ago, Earth was just lighting the kindling for the fires of life. Microbes were laying the stones for the eventual road to mankind. Around the same time, two massive tsunamis, each up to 400 feet high, blasted their way across Mars. At the time the red planet was only just over a billion years old–which, by planetary standards, is reasonably young.
Evidence of the tsunamis was discovered by a team of scientists from the Planetary Science Institute in Tucson, Arizona. J. Alexis Rodriguez, who led the team, reported their find in Scientific Reports.
According to researchers, the tsunamis were most likely caused by meteors colliding with the planet. Ancient Mars had oceans on it, and the tsunamis created by the collisions were far larger than anything that our earth has ever seen–19 miles in diameter and, according to estimates, about 400 feet high. The study found two such tsunamis, taking place more than a million years apart.
Although these mega-waves happened on a different planet, most of the same rules apply: they still caused massive devastation, pushing boulders and soil far inland, drastically altering the entire landscape. Still, though, after 3.4 billion years, the effects weren’t easy to find. Rodriguez and his team were looking at Chryse Planitia and Arabia Terra, two sections of the northern side of Mars. They were using thermal cameras on the Mars Oribiter when they noticed features far from the old oceans that shouldn’t have been there. At higher elevations, the thermal cameras showed “bright, rocky, and boulder-rich exposures that bordered dark and flat sediment layers perched on a slightly higher elevation. That bright rocky exposure was churned up by the tsunami billions of years ago, where the dark swath stayed dry.”
As the water receded, it carved large channels out of the surface of the planet. Just behind the masses of stone and boulders along the high water marks, the team found evidence of seven meteor impact sites–and all of them were large enough to create the massive waves.
They weren’t only incredibly wide and tall, either. The Mars tsunamis were powerful on a scale that’s almost unimaginable. Were something like that to happen here on earth, the devastation would be catastrophic. The first tsunami was a little smaller than the first–covering some 300,000 square miles–while the second was much larger. It pounded inland almost 400 miles, covering about 400,000 square miles. Compared to those, the very worst of our tsunamis are mere ripples. According to Nat Geo, the Indian Ocean tsunami in 2004 was at most 30 feet high, and it killed somewhere around 150,000 people.
Before that, the worst on record was in the South China Sea in the late 1700s, when an estimated 40,000 people died. Flooding doesn’t generally extend more than a thousand feet inland, although in 2004, it extended about a mile, which was largely to blame for the enormous death toll.
Perhaps most interestingly, the second tsunami may hold clues to the possibility of life on Mars. For millions of years, the oceans on Mars were probably a slushy, near-freezing liquid. The tsunami pushed giant, slushy ice-boulders far inland, depositing their ancient secrets far from their origins. Those slushy deposits could have turned into pools that would, scientists hope, be perfect places for life to blossom. “We have already identified some areas inundated by the tsunamis where the ponded water appears to have [been formed by this ice], said Rodriguez. “As a follow-up investigation, we plan to characterize these terrains and assess their potential for future robotic or human exploration.”
