Megatsunami swept across Mars after a massive asteroid hit the Red Planet
A Martian megatsunami — a giant deadly wave that may be more than 80 stories high — may have swept across the Red Planet after a cosmic impact similar to the one that likely ended the Earth’s age of dinosaurs, a new study finds.
Although the surface of Mars is now cold and dry, much evidence suggests that the Red Planet was covered with an ocean of water billions of years ago. Previous research found signs that two meteor impacts may have resulted a few megatsunamis (opens in new tab) about 3.4 billion years ago. The older tsunami inundated about 309,000 square miles (800,000 square kilometers), while the more recent one drowned an area of about 386,000 square miles (1 million square kilometers).
A Study from 2019 found what could be ground zero for the younger megatsunami – Lomonosov Crater, a 75-mile-wide (120 km) hole in the ground in the icy plains of the Arctic region of Mars. The large size suggests that the cosmic impact that dug the hole itself was large, comparable in scale to that of a 6-mile-wide (10 km) asteroid That struck near what is now the town of Chicxulub in Mexico 66 million years ago, leading to a mass extinction that killed 75% of Earth’s species, including all dinosaurs except birds.
Related: Stunning Mars photos from the Curiosity rover show ancient climate shifts
Now the new study finds what could be the origin point of the older megatsunami — 69-mile-wide (111 km) Pohl crater, which formed the International Astronomical Union named after science fiction master Frederick Pohl in August.
The scientists focused on NASA’s landing site viking 1, the first spacecraft to successfully operate on the surface of Mars. Viking 1 landed in Chryse Planitia in 1976, a smooth circular plain in the northern equatorial region of Mars. The probe touched down near the terminus of a giant channel, Maja Valles, carved by an ancient catastrophic flood, the first time scientists have identified an alien landscape carved by a river.
Unexpectedly, instead of discovering the kind of flood-related features scientists had expected of the site, such as streamlined islands worn smooth by running water, they found a boulder-strewn plain. Now the researchers suggest that these boulders may be debris from a megatsunami, the giant wave that carries pulverized rock away from the site of the cosmic impact.
“The seafloor would have been thrown up into the air, feeding the gulf with sediments and likely contributing to the development of a catastrophic debris flow front,” lead author Alexis Rodriguez, a planetary scientist at the Planetary Science Institute in Arizona, told Space.com
The scientists analyzed maps of the surface of Mars, created by combining images from previous missions to the planet. This helped them identify Pohl, which is about 560 miles (900 km) from Viking 1’s landing site, in a region of the northern Martian lowlands.
“The northern plains of Mars comprise a huge basin where an ocean formed about 3.4 billion years ago and then froze,” Rodriguez said. “The ocean is believed to have formed as a result of catastrophic flooding released from aquifers. So my first approach to looking for a megatsunami-causing impact was to look for a crater under the ocean’s frozen residue and above the channels which drained the ocean-forming floods.” Pohl was the only crater the scientists found that met this criterion, he noted.
The researchers simulated cosmic effects on this region to see what type of impact Pohl might have caused. Their findings suggest that Viking 1’s landing site “is part of a megatsunami deposit placed about 3.4 billion years ago,” Rodriguez said.
Then the scientists used simulations to understand how a crater similar in size to Pohl could have formed. If an asteroid experienced strong ground resistance, it would have had to be about 9 km, with the impact releasing energy equivalent to 13 million megatons of TNT; if the asteroid met weak ground resistance, it would have been only 3 km across, releasing the energy of 500,000 megatons of TNT. (By comparison, the most powerful atomic bomb ever tested, Russia’s Tsar Bomba, had the power of just 57 megatons of TNT.)
Both simulated impacts generated a megatsunami that reached as far as 1,500 km from the impact site, more than enough to reach Viking 1’s landing site. The massive wave would have initially stretched about 1,640 feet (500 meters) high and about 820 feet (250 m) high on land. Those stats would make the Pohl impact comparable to that of Chicxulub: 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 produced a tsunami about 650 feet (650 feet). 200 m) high on land.
In the future, the researchers want to further investigate how Mars’ ancient ocean might have changed between the two megatsunami 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 that last for tens of thousands of years and provide energy and nutrient-rich environments,” Rodriguez said in a statement. pronunciation.
The research is described in a newspaper (opens in new tab) published Thursday (Dec. 1) in the journal Scientific Reports.
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