Evidence of ancient tsunamis on Mars

Satellite images suggest dramatic rearrangements of sediments / ALEXIS RODRIGUEZ

Scientists think they see evidence of two huge tsunamis having once swept across the surface of Mars.

They point to satellite data suggesting a major redistribution of sediments over a large region at the edge of the Red Planet’s northern lowlands.

The US-led team argues that asteroid or comet strikes into an ocean of water could have triggered the giant waves.

Such events could only have occurred more than three billion years ago when the planet was wetter and warmer.

Today, Mars is dry and cold, and any impact would merely dig out a dusty hole.

But researchers have long speculated that the low, flat terrain in Mars’ northern hemisphere could have hosted an ocean if the climate conditions were just right.

The nagging doubt with this theory has been the absence of an identifiable shoreline – something the new study could now help explain.

If tsunamis regularly inundated the “land”, dumping sediments and scouring new flow channels, they could over time have disguised what otherwise would have been an obvious “coast”.

“For more than a quarter century, failure to identify shoreline features, consistently distributed along a constant elevation, has been regarded as inconsistent with the hypothesis that a vast ocean existed on Mars approximately 3.4 billion years ago,” said Alexis Palmero Rodriguez from the Planetary Science Institute in Tuscon, Arizona.

“Our discovery offers a simple solution to this problem: widespread tsunami deposits distributed within a wide range of elevations likely characterise the shorelines of early Martian oceans.”

Dr Rodriguez and colleagues’ tsunami findings are due to appear on Thursday in the Nature journal Scientific Reports. Their work centres on two connected regions of Mars, known as Chryse Planitia and Arabia Terra.

The team interprets the sediments observed by satellite to betray the action of two ancient mega-tsunamis.

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