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Ancient tsunamis on Mars?

A study suggests that 2 large meteorites hit Mars billions of years ago and triggered mega-tsunamis in Martian water oceans.

The Valles Marineris region on Mars, where Alberto Fairén and other astronomers examined tsunami-affected shorelines from meteor impacts. Image via NASA/JPL-Caltech

The Valles Marineris region on Mars, where astronomers examined tsunami-affected shorelines from meteor impacts. Image via NASA/JPL-Caltech

A new study, published May 19, 2016 in Scientific Reports suggests that two large meteorites that hit Mars billions of years ago triggered mega-tsunamis in the planet’s oceans. The study authors say that these gigantic waves forever scarred the Martian landscape and yielded evidence of cold, salty water oceans conducive to sustaining life.

According to the researchers, the geologic shape of what were once ocean shorelines through Mars’ northern plains is evidence that two large meteorites – hitting the planet millions of years apart – triggered a pair of mega-tsunamis.

Alberto Fairén, Cornell visiting scientist in astronomy and principal investigator at the Center of Astrobiology, Madrid, one of the study’s authors. Fairén said in a statement:

About 3.4 billion years ago, a big meteorite impact triggered the first tsunami wave. This wave was composed of liquid water. It formed widespread backwash channels to carry the water back to the ocean.

White arrows indicate the edges of the ancient deposits. Image via Alexis Rodriguez

White arrows indicate the edges of the ancient deposits. Image via Alexis Rodriguez

The scientists found evidence for another big meteorite impact, which they think triggered a second tsunami wave. In the millions of years between the two meteorite impacts and their associated mega-tsunamis, Mars went through frigid climate change, where water turned to ice, Fairén said:

The ocean level receded from its original shoreline to form a secondary shoreline, because the climate had become significantly colder.

The second tsunami, the study suggests, formed rounded lobes of ice. Fairén said:

These lobes froze on the land as they reached their maximum extent and the ice never went back to the ocean – which implies the ocean was at least partially frozen at that time.

Our paper provides very solid evidence for the existence of very cold oceans on early Mars. It is difficult to imagine Californian beaches on ancient Mars, but try to picture the Great Lakes on a particularly cold and long winter, and that could be a more accurate image of water forming seas and oceans on ancient Mars.

These icy lobes retained their well-defined boundaries and their flow-related shapes, Fairén said, suggesting the frozen ancient ocean was briny. He said:

Cold, salty waters may offer a refuge for life in extreme environments, as the salts could help keep the water liquid … If life existed on Mars, these icy tsunami lobes are very good candidates to search for biosignatures.

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Bottom line: A new study, published May 19, 2016 in Scientific Reports, suggests that two large meteorites hit Mars billions of years ago and triggered mega-tsunamis in Martian water oceans.

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Eleanor Imster

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