Huge Tsunamis Shaped Face of Mars Billions of Years Ago

Rings of sediment created by two Mars tsunamis are shown here in red and black outlines, and (C) shows a ridge of Martian soil created by the ancient deluge of water. J. Alexis P. Rodriguez et al / Scientific Reports

About 3.4 billion years ago, a large meteor slammed into an ocean covering the northern lowlands of Mars, new research shows. This meteor was significantly smaller than the one that killed dinosaurs on Earth, but it was still large enough to create a crater nearly 20 miles in diameter. More importantly, it produced a tsunami with a height of up to 400 feet, sending water cascading far inland, a plume of expanding blue on a red planet.

This violent deluge left deep marks in the Martian landscape, and they still remain. In a study published May 19 in the journal Scientific Reports, researcher Alberto Fairén and colleagues analyzed the sedimentary evidence, which showed that these landscape etchings could've been created only by this tsunami—and another one that struck later.

After the first meteor, the planet cooled down, and the ocean partially froze, says Fairén, an astrobiologist with Cornell University and Spain's Centro de Astrobiología. Then a second space rock of a similar size slammed into the slushy sea, producing another tsunami. But this one froze shortly afterward, leaving evidence of its existence behind. Fairén says it's possible the tsunami actually began to freeze into a type of ice-rich "slurry" as it moved along, which might have looked something like this video of an "ice surge" in the Canadian province of Saskatchewan.

The icy lobes of the second tsunami remained in their "flow-related-shapes...suggesting that they preserve their original composition: frozen ancient ocean water brines," Fairén says. This interests researchers since these briny waters "may offer a refuge for life in extreme environments, as the salts could help keep the water liquid." (Very salty water has a lower freezing point.) Therefore, "these icy tsunami lobes are very good candidates to search" for life Mars, he adds.

"If Mars was red back then, the ocean, and the tsunami might have also been red," says study first author Alexis Rodriguez, with the Planetary Science Institute "So, if you were standing on the shoreline you would have seen a 50 meter [164 foot] wall of red water hurdling towards you."

NASA made waves in September 2015 when the agency announced that very briny water had been found flowing on the surface of Mars. John Grunsfeld, an astronaut and associate administrator of NASA's Science Mission Directorate in Washington, D.C., said at the time that the announcement was "exciting because it suggests that it would be possible for there to be life on Mars today." Researchers had already established that water used to be much more prevalent on Mars, but that much of it was stripped away by solar wind.

The icy tsunami remnants are located not too far from the landing site of the European Space Agency's ExoMars 2020 rover, which will be equipped to look for signs of life, Fairén says.

Thermal image showing ice-rich lobes (outlined by yellow line), which the researchers interpret to be the remnants of tsunami waves that transitioned into slurry ice-rich flows. Scientific Reports