Megatsunami on Mars Generated 3.4 Billion Years Ago at Pohl Crater

View of the Chryse Planitia region showing the locations of the Viking 1 and Pathfinder landing sites and the Maja Valles channel. The newly discovered Pohl Crater is shown by the red triangle. The blue region is the reconstruction of the shallow sea in the northern martian lowlands, and the brown areas show the extent of the megatsunamisโ€™ largest lobes, as determined by computer-based simulations. Credit: Rodriguez et al., 2022.

Scientists have discovered evidence of a megatsunami generated by an asteroid impact on Mars early in its history. This discovery dates back to the Viking 1 Lander (V1L), the first spacecraft to land successfully on Mars in 1976. The probe landed in the Chryse Planitia region near the terminus of a giant channel, Maja Valles, which was found to have been carved by catastrophic floods roughly 3.4 billion years ago based on remote sensing data. However, the probe discovered a boulder-strewn surface that lacked any landforms associated with flowing water.

A team of scientists led by Alexis Rodriguez at the Planetary Science Institute proposes an alternative explanation based on the discovery of a new crater located 900 kilometers northeast of the V1L landing site. Pohl Crater, which was identified using data from the Mars Reconnaissance Orbiter (MRO) Context Camera (CTX), measures 68 miles in diameter and is located in the northern martian lowlands. This area has been proposed to have been a shallow sea billions of years ago. The team hypothesizes that an asteroid struck this sea with such force that it caused a massive wave to ripple across the surface, generating a catastrophic tsunami. Computer-based simulations show that the resulting wave would have been up to 800 feet tall. It would have surged inland for hundreds of miles and altered the martian landscape, leaving behind boulder-strewn terrains similar to the V1L landing site. By analyzing the geological features at the landing site and simulating the physics of the impact, they were able to reconstruct the extent of tsunami deposits. They found that the deposits would reach the Maja Valles.

This study has the potential to revise the interpretations from the V1L mission. For example, the landing site may consist of dredged-up ocean sediment containing evidence of life, posing important implications in the investigation of martian habitability. READ MORE