Volcanoes could still be active on Mars

Mars, the red planet, is a dead planet. For billions of years nothing has happened, except the occasional dust storm. That's what astronomers believed. Until now.

Astronomers had long believed that much of the planet's volcanic activity occurred between 3 and 4 billion years ago.

Now, orbiters circling Mars have provided imagery and data of a previously unknown area of interest. This latest information shows evidence of volcanic activity that must have happened within the last 50,000 years[1]. That is extremely young, astronomically speaking.

A smooth, dark area stretches for more than 10 kilometres. It's surrounded by a 30 kilometres-long volcanic fissure in the Cerberus Fossae system of faults where the Martian crust has pulled apart. This intriguing feature is located in the Elysium Planitia region, a plain spread across the planet's equator and second largest volcanic region.

"This may be the youngest volcanic deposit yet documented on Mars," said lead-author David Horvath, a research scientist at the Planetary Science Institute, in a statement. "If we were to compress Mars' geologic history into a single day, this would have occurred in the very last second."

The researchers believe the evidence, including how the material was distributed on the surface, matches a pyroclastic eruption. This type of volcanic eruption occurs when magma explodes due to expanding gases.

"When we first noticed this deposit, we knew it was something special," said study co-author Jeff Andrews-Hanna, an associate professor at the University of Arizona Lunar and Planetary Laboratory, in a statement. The deposit was unlike anything else found in the region, or indeed on all of Mars, and superficially similar resembles featuresinterpreted as pyroclastic deposits on the Moon and Mercury."

Most of the evidence of previous volcanic activity is similar to lava flows that we might see on Earth. But this one is different.

"This feature overlies the surrounding lava flows and appears to be a relatively fresh and thin deposit of ash and rock, representing a different style of eruption than previously identified pyroclastic features," Horvath said. "This eruption could have spewed ash as high as 10 kilometres into Mars' atmosphere. It is possible that these sorts of deposits were more common but have since been eroded or buried."

[1] Horvath et al: Evidence for geologically recent explosive volcanism in Elysium Planitia, Mars in Icarus. See here.