Scientists Discover When Volcanoes Erupted on Mars

Scientists have long suspected that volcanoes erupted on Mars in the past, but only recently have they been able to determine when these eruptions occurred. An analysis of surface features on Mars has indicated that there was intense volcanic activity on the planet approximately 3.5 billion years ago, according to a study published in the journal Nature Astronomy.

On March 4, 2022, the InSight lander's seismometer recorded one of the strongest marsquakes in recent years, measuring 4.7 magnitude and designated as S1222a. The quake lasted six hours. This and other weaker tremors have shown scientists that there are still some minor tectonic processes occurring on the planet.

Unlike Earth, Mars does not exhibit volcanic or strong tectonic activity today. Furthermore, nearly half of Mars's surface is over 3.5 billion years old, and more than 70 percent is over 3 billion years old. This fact suggests that throughout this entire time period, the planet has not undergone significant mixing of its interior, a process that requires substantial tectonic activity, as seen on Earth.

Recent studies have allowed scientists to propose that this has not always been the case, but questions about Mars’s geological activity remained unexplored during the first billion years after its formation.

Researchers led by Joseph Michalski from the University of Hong Kong decided to investigate the morphology and mineralogy of Martian rocks in the region known as Eridania, a hypothetical ancient lake covering more than 1 million square kilometers in the planet’s southern hemisphere. The rocks in this area preserve some of the clearest evidence of the planet's ancient magnetic field and past volcanic activity.

They studied them using tools on three orbital missions—Mars Global Surveyor, Mars Odyssey, and Mars Reconnaissance Orbiter—and discovered 63 pieces of evidence indicating ancient volcanic activity, including lava domes, stratovolcanoes, pyroclastic shields, and caldera complexes. Moreover, there could be hundreds more in the Eridania region alone.

"One of the main differences on Mars is the presence of very large shield volcanoes that are comparable in size to those on the Moon," the study states. Scientists found that all of these are considered evidence of a vigorous phase of volcanic activity that occurred on Mars around 3.5 billion years ago.