Depending on the type of soil in the area of the explosion, its strength could range from 0.5 to 13 million megatons. Astronomers named the resulting huge crater after the famous science fiction master Frederick Paul.
According to modern concepts, the northern hemisphere of the Red Planet was once covered by an ocean that occupied one-third of its surface. Today this area, the former seabed, lies four to five kilometers below the surrounding plains. Nearby, there are traces of serious wave action, similar to the traces of a powerful tsunami, but it looks too strong for an event of volcanic origin - as well as traces of all-planet tsunami, available in the Earth's layers of age 66 million years. The authors of a new paper in Scientific Reports determined the causes of this megatsunami, and estimated the power of the event.
Numerous traces of an ancient and particularly strong tsunami on Mars 3.4 billion years ago have long drawn the attention of scientists. Because of its large scale, it was logical to assume that it was caused by the fall of a large asteroid. But it remained unclear exactly where it fell. And without finding the crater, it is impossible to estimate the force of the explosion that caused it.
The researchers have conducted a thorough analysis of the images of the surface of the fourth planet and found a crater with a diameter of about 110 kilometers on the plain of Chris. They named it after the famous science fiction writer Frederick Paul (1919-2013).
At the time of the ancient Martian ocean this area was about 120 meters below sea level - that is, in common parlance, part of the continental shelf. This is the place where it is easiest for an asteroid explosion to generate powerful, far-reaching waves. A similar thing happened on Earth 66 million years ago, when a large asteroid fell off the coast of modern Mexico, also on the shelf.
According to calculations based on the parameters of the crater found, it could have been caused by an explosion of at least half a million megatons - ten thousand times more powerful than the King Bomb, the most massive explosion ever produced by humans. And this was the power if the asteroid hit soft rocks. But if the rocks at the point of impact were denser, the explosion could be much more powerful - up to 13 million megatons, or about a quarter of a million Tsar Bombs.
According to the conservative low explosion scenario, the height of the tsunami wave that struck the coastal regions of Mars at this point would have been up to 250 meters. The waves then entered areas 1,500 kilometers away from the seashore. Researchers compare this event to the mega tsunami after the fall of the Chicxulubu asteroid 66 million years ago. Back then, the impact is believed to have hit the seafloor, 200 meters below the surface of the ocean. The diameter of the crater immediately after the explosion was over 100 kilometers, and the height of the megatsunami reached 200 meters. It is true that waves with such a height only struck the Americas; Africa then reached only about eight meters high.
The power of the explosion 66 million years ago was greater than the one that formed Paula Crater. However, the impact occurred in a deeper layer of water and a different seafloor geology, so the tsunami was smaller here.
This impact was far from being the most powerful in the history of the Red Planet. In its southern hemisphere, there is the so-called Hellas Plain, 2,300 kilometers in diameter, whose bottom is nine kilometers below the surrounding area. In addition to this very large impact crater (there is nothing similar on other bodies of the solar system), Mars has even more impressive traces of impacts.
For example, a number of researchers believe that its northern polar basin was formed by the impact of a body 1,900 kilometers in diameter. It occupies 40% of the planet, i.e. about fifty million square kilometers. If its impact status can be confirmed, it will become the undisputed champion of the Solar System among the asteroid impact traces.
