A Martian megatsunami – a giant killer wave that may have reached more than 80 stories – may have passed through the Red Planet after a cosmic impact similar to the one that likely ended the age of dinosaurs on Earth, according to a new study.
Although the surface of March is now cold and dry, there is ample evidence to suggest that water from an ocean covered the Red Planet billions of years ago. Previous search found signs that two meteor impacts could have triggered a pair of megatsunamis (opens in a new tab) about 3.4 billion years ago. The oldest tsunami inundated about 309,000 square miles (800,000 square kilometers), while the most recent drowned an area of about 386,000 square miles (1 million square kilometers).
A study 2019 found what could have been ground zero for the youngest megatsunami – Lomonosov Crater, a 75-mile-wide (120 km) 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 large, on a scale similar to 6 miles (10 km) wide. asteroid this struck near what is now the town of Chicxulub in Mexico 66 million years ago, triggering a mass extinction that killed 75% of Earth’s species, including all dinosaurs except birds.
Related: Stunning photos of Mars taken by the Curiosity rover show ancient climate change
Now the new study finds what may be the origin point of the ancient megatsunami – the 69-mile-wide (111 km) Pohl crater, which the International Astronomical Union named after the great master of science fiction Frederic Pohl in August.
Scientists focused on the NASA landing site Viking 1, the first spacecraft to successfully operate on the Martian surface. Viking 1 landed in 1976 at Chryse Planitia, a smooth circular plain in the northern equatorial region of Mars. The probe landed near the end of a giant channel, Maja Valles, carved out by an ancient catastrophic flood, the first time scientists have identified an alien landscape carved out by a river.
Unexpectedly, instead of discovering the kind of flood-related features that scientists expected from the site, such as streamlined islands worn down by flowing water, they found a boulder-strewn plain. Now researchers suggest that those boulders could be debris from a megatsunami, the giant wave carrying the pulverized rock away from the site of the cosmic impact.
“Seafloor would have been thrown through the air, feeding the wave of sediment and likely contributing to the development of a catastrophic debris flow front,” Space.com told Space.com
Scientists analyzed maps of the Martian surface, created by combining images from previous missions to the planet. This helped them identify Pohl, which is located about 900 km from Viking 1’s landing site, in a region of the northern Martian lowlands.
“The northern plains of Mars include a huge basin where about 3.4 billion years ago an ocean formed and then froze,” Rodriguez said. “The ocean is considered to have formed due to catastrophic flooding released from aquifers. So my initial approach to looking for an impact triggering a megatsunami was to look for a crater beneath the frozen ocean tailings and above. above the canals which poured out the floods forming the ocean. Pohl was the only crater found by scientists that met this criterion, he noted.
The researchers simulated cosmic impacts on this region to see what kind of impact Pohl might have created. Their findings suggest that the Viking 1 landing site is “part of a megatsunami deposit laid down around 3.4 billion years ago,” Rodriguez said.
Next, the scientists used simulations to figure out how a crater of similar dimensions to Pohl might have formed. If an asteroid encountered strong ground resistance, it would have had to be about 9 km (5.6 miles) away, with the impact releasing energy equivalent to 13 million megatons of TNT; if the asteroid encountered low ground resistance, it might have been only 3 km in diameter, releasing the energy of 500,000 megatons of TNT. (In comparison, the most powerful nuclear bomb ever tested, the Tsar Bomba of Russia, had the force of only 57 megatons of TNT.)
Both simulated impacts generated a megatsunami that reached up to 930 miles (1,500 km) from the impact site, more than enough to reach the landing site of Viking 1. The massive wave could have initially spread about 1,640 feet (500 meters) high and stand about 820 feet (250 m) high on land. These statistics would make the Pohl impact similar to the Chicxulub impact: previous work has suggested that the impact struck about 650 feet (200 m) below sea level, formed a crater about 60 miles (100 km) ) wide and triggered a tsunami about 650 feet (200 m) high on land.
Going forward, researchers want to further investigate how the ancient Martian ocean might have changed between the two megatsunamis to see what potential biological effects that change might have had, Rodriguez said.
“Immediately after its formation, the crater would have generated submarine hydrothermal systems lasting tens of thousands of years, providing energy- and nutrient-rich environments,” Rodriguez said in a statement. statement.
The research is described in a document (opens in a new tab) published Thursday (December 1) in the journal Scientific Reports.
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