Scientists from NASA and the Planetary Science Institute in Tucson, Ariz., have identified a possible supervolcano on Mars—the first discovery of its kind.
The volcano in question, a vast circular basin on the face of Mars, had been previously classified as an impact crater. Researchers believe the basin is what remains of an ancient supervolcano eruption. Their evaluation is based on images and topographic data from NASA's Mars Odyssey, Mars Global Surveyor and Mars Reconnaissance Orbiter spacecraft, as well as the European Space Agency's Mars Express orbiter.
Researchers laid out their case that the basin, recently named Eden Patera, is a volcanic caldera. Because a caldera is a depression, it can look like a crater formed by an impact, rather than a volcano. They also suggest a large body of magma loaded with dissolved gas (similar to the carbonation in soda) rose through thin crust to the surface quickly. This supervolcano would have blown its contents far and wide if the top came off suddenly. After the material is expelled from the eruption, the depression that is left can collapse even further, causing the ground around it to sink.
Volcanoes previously had not been identified in the Arabia Terra region of Mars, where Eden Patera is located. The battered, heavily eroded terrain is known for its impact craters. But as this particular basin was closely, the lack of the typical raised rim of an impact crater was apparent. A nearby blanket of ejecta, the melted rock that splashes outside the crater when an object hits was also not found. The absence of these key features led researchers to suspect volcanic activity.
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