Two Mega Tsunamis Hit Mars Millions of Years Ago

The Martian ocean said to have existed at the planet’s northern hemisphere might have witnessed at least two huge tsunamis caused by the impact of meteors. New evidence documented in a paper published in Scientific Reports mentions traces of these events. More interestingly, the results of the study provide hope for the theory of microbial life on Mars.

The ocean said to have existed on the northern pole of Mars. Photo credits: NASA/GSFC.
The ocean said to have existed on the northern pole of Mars. This water (most of it) would have later disappeared into space. Photo credits: NASA/GSFC.

The new study, conducted by researchers from the Planetary Science Institute (PSI) based in Arizona, might be bringing ourselves closer to elucidating a mystery question pertaining to the existence of the ocean on the Martian surface. Based on past suggestions, scientists believe that the northern part of the planet was once covered with a cold, salty ocean. That would have been 3.4 billion years ago or so. This Martian sea might have held microbial life in its midst. Things probably changed when the climate of the planet transformed such that the water evaporated into space. All of this remains a theory obviously, since no clear evidence has been found to confirm it. However, the new research constitutes the strongest evidence pointing at the occurrence of the northern ocean.

This updated information was obtained after scientist J. Alex P. Rodriguez (from PSI) and his team carried out an elaborate analysis of Mars’ northern plans: they found compelling evidence of the existence of the ocean in the form of sedimentary deposits and round lobes of ice.

The tsunamis are said to have impacted Mars such that both its shorelines and inland regions of that time were reshaped geologically. The whole of Mars’ landscape was remade because of these waves (that are said to have reached 120 meters high) – these impacts were so massive that they left certain features that apparently bear testimony to their occurrence. The meteors that caused these waves happened at two different instances, millions of years apart from each other; they both resulted in craters making around 30 km in width.

The first tsunami would have caused backwash channels taking water back to the sea – this is indicated by the current huge sedimentary deposits. As for the second tsunami, it happened when the climate had shifted to a much colder trend such that water was changed to ice – this one left the round lobes of ice as traces. The latter kept their flow-related shapes after the tsunami water turned into ice, suggesting that the water was rich in salt. Rodriguez’s colleague, Alberto Fairén, interprets the data as meaning that the frozen lobes might have never gone back to the ocean, suggesting that the latter was probably partially frozen by that time. All of this indicates the possibility of the existence of very cold oceans on Mars millions of years ago.

Left: Color-coded digital elevation model of the study area showing the two proposed shoreline levels of an early Mars ocean that existed approximately 3.4 billion years ago. Right: Areas covered by the documented tsunami events extending from these shorelines. (Image and caption credit: Alexis Rodriguez)
Left: Color-coded digital elevation model of the study area showing the two proposed shoreline levels of an early Mars ocean that existed approximately 3.4 billion years ago. Right: Areas covered by the documented tsunami events extending from these shorelines. (Image and caption credit: Alexis Rodriguez)

Rodriguez believes this to have great “astrobiological implications”, specially the part suggesting salty water; the salt would have kept the water in a liquid state which might have fostered life.

Furthermore, Fairén thinks that the icy tsunami lobes might be of help to look for biosignatures.

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