A Martian megatsunami – agiant killer wave that may have reached more than 80 stories tall – may have raced across the Red Planet after a cosmic impact similar to the one that likely ended Earth’s age of dinosaurs. Although the surface of Mars is now cold and dry, a great deal of evidence suggests that an ocean’s worth of water covered the Red Planet billions of years ago. Previous research found signs that two meteor strikes might have triggered a pair of megatsunamis about 3.4 billion years ago. The older tsunami inundated about 800,000 square kilometres (309,000 square miles), while the more recent one drowned a region of about 1 million square kilometres (386,000 square miles).
A 2019 study found what may have been ground zero for the younger megatsunami – Lomonosov crater, a 120-kilometre (75-mile) wide hole in the ground in the icy plains of the Martian arctic. Its large size suggests that the cosmic impact that dug the hole itself was big, similar in scale to the one from a ten-kilometre (six-mile) wide asteroid that struck near what is now the town of Chicxulub in Mexico 66 million years ago, triggering a mass extinction that killed off 75 per cent of Earth’s species, including all dinosaurs except birds. A new study has found what may be the origin point of the older megatsunami – 111-kilometre (69-mile) wide Pohl crater, which the International Astronomical Union named after science-fiction grandmaster Frederik Pohl in August.