Scientists think an asteroid might have caused Mars’ ancient tsunamis
A team of astronomers now thinks that the asteroid impact that produced the Lomonosov crater on Mars’ surface was also the reason for the 3 billion-year-old massive tsunamis registered in the planet. These ancient tidal waves are known for sweeping the entire surface of the Red Planet, and scientists have been looking for its origins for quite some time.
In the recent decades, many investigation teams have developed hypotheses concerning the possible causes of the old tsunamis during the time Mars had areas full of water. However, this latest study published in the Journal of Geophysical Research—Planets and presented in the 48th Lunar and Planetary Science Conference, is the first one to link a particular crater to a particular tsunami.
Scientists think an asteroid might have caused Mars’ ancient tsunamis. Image credit: Reuters / NASA / JPL-Caltech / Handout / Popular Science
One of the controversial topics of each investigation in the past has been the extension of those watered Mars’ areas. The fact that the planet possessed water at some point in its history is commonly accepted, but where and how much water there was are questions that remain unanswered.
In the latest study, the team of researchers was able to identify a group of lobate deposits that are usually linked with Mars’ water movements. These deposits apparently could have flowed into the Southern region of the planet from the Northern region, which provides evidence to affirm that in that last region could have been an ocean many millions of years ago.
According to the lead author of the study, François Costard, the fact that the team had found those deposits that tsunamis often produce is key to the study and its allegations. Also, the fact that the location of these deposits was the dichotomy between the northern and southern hemisphere only supports the hypothesis of the existence of a northern sea located in Mars, Costard said to BBC this Sunday.
Asteroids, tsunamis and lobate deposits
The lobate deposits observed were one of the most significant findings when making the study, Dr. Clifford, from the Lunar and Planetary Institute in Houston, explained to the press. Clifford says that these deposits propagate through the uphills coming from the northern region, which gives evidence to the whole team when it comes to numerical modeling and therefore “provides a very persuasive case for an ocean at this time.”
“There’s…[a] set of landforms that we see along the coastline called thumbprint terrain,” Stephen Clifford, study co-author, told the BBC. “The reflection of the tsunami waves from the coast and their interaction with a second set of tsunami waves, predicted by the numerical modeling, would have resulted in sediment deposition that’s very similar to what we actually observe on Mars.”
The fact that the planet possessed water at some point in its history is commonly accepted, but where and how much water there was are questions that remain unanswered. Image credit: ESO / M. Kornmesser / N. Risinger (skysurvey.org), Creative Commons / Harvard University, SITN
Given those pieces of geological evidence, they alleged in the study that the known massive tsunamis that happened more than 3 billion years ago were caused by the impact of an asteroid. There were not many asteroids that hit Mars’ northern region at that time, which means that the impact that generated the 75-mile-long Lomonosov crater seems to be guilty.
“It was a really large-scale, high-speed tsunami. At the very beginning, a crater of 70 kilometers [43.5 miles] in diameter was created by the impact. This expelled a huge volume of water, with wave propagation at 60 meters per second [134 miles per hour]. The initial wave was about 300 meters [984 feet] in height. After just a few hours, that tsunami wave reached the paleo-shoreline located at a few hundred kilometers from the impact crater,” Dr. Costard said when presenting the study.
According to the study, the impact of the asteroid was so high that it created two distinct tsunami waves. This produced several deposits in the adjacent zones with almost 100 miles of separation, caused by waves more than 300 feet tall.
Study critics: Tsunamis and lobate deposits not related
Even when the investigation team has no doubts about the relation between the tsunamis and the lobate deposits, many experts have challenged this allegation in the past. In recent studies, the existence of these deposits has other phenomena as an explanation, like glacier movements or mud flows. However, since it is extremely difficult to determine what happened on Mars’ surface 3 billion years ago, there is no exact answer to that issue.
According to Dr. Clifford, it’s tough to think of a different explanation to the lobate deposits that is not the massive ancient tsunamis, essentially because of their location (the dichotomy boundary between the northern and southern hemisphere).
Clifford says that the key point regarding the tsunamis is the fact that it could lead to the assumption of a northern plain ocean that had vast amounts of water, and if this substantial amount of water actually was on Mars’ surface, it could change the planet’s whole inventory and even portray itself as a host for life at some point.