Giant Tsunami on Mars Caused by Asteroid Impact

New evidence of oceans on the northern plains of Mars

The Lomonosov crater in Mars' Northern District is believed to be the source of massive tsunamis that swept across the planet’s surface. The asteroid is believed to have caused 150m- high waves, supporting the theory that Mars' northern lowland region once supported a large ocean.

Steve Clifford and Francois Costard found evidence of a possible ancient shoreline:

"We found typical tsunami deposits along the dichotomy between the northern hemisphere and southern hemisphere of Mars, it supports that there was, at that time, a northern ocean," said Costard of the sediment distribution on the northern plains.

Evidence of a lobate flow deposit was found on the dichotomy boundary Clifford explains:

"These lobate deposits propagate uphill from the northern plains and do so in close association with a potential palaeo-shoreline. The predictions of the numerical modelling that François and his colleagues have done provide a very persuasive case for an ocean at this time there's also a second set of landforms that we see along the coastline called thumbprint terrain.... the reflection of the tsunami waves from the coast and their interaction with a second set of tsunami waves, predicted by the numerical modelling, would have resulted in sediment deposition that's very similar to what we actually observe on Mars."

The thumbprint terrains probably formed when two sets of tsunami waves interactedImage: The thumbprint terrains probably formed when two sets of tsunami waves interacted, JGR - PLANETS

This particular area was previously thought to have been formed as a result of mud volcanoes, glaciers or mud flows. If there is evidence of a giant tsunami 3 billion years ago, then there must have been an ocean in the northern plains.

"That's the key point here; it indicates that there was a substantial amount of water in residence on the Martian surface at this time and that has likely implications for the total inventory of water on Mars." Says Clifford.

The impact crater responsible for the two giant tsunami waves is a 120km wide bowl named Lomonosov respectfully named after Mikhail Vasilyevich Lomonosov a Russian polymath from the 18th century. Two large waves formed from the impact- "It was a really large-scale, high speed tsunami. At the very beginning, a crater of 70km in diameter was created by the impact. This expelled a huge volume of water, with wave propagation at 60m/second.”

The first of the two waves was 300m high, it would have reached the palaeo-shoreline within hours crushing on hills and plateaus.

An ocean on Mars could hint at signs of life. Such biology on Mars would make the planet more inhabitable. Clifford is optimistic:

"There is ambiguity in all the various lines of evidence that have been cited regarding whether Mars is water-rich or water-poor. But the morphologic evidence that's been presented here is a very persuasive case for a water-rich planet."

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