Mars may show evidence of supervolcanos

New Scientist : An area of Mars called Arabia Terra may be the site of a pair of supervolcanos . Jacob Bleacher of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and Joseph Michalski of the Planetary Science Institute in Tucson, Arizona, have proposed that two sets of irregular depressions are the craters of the volcanos. On Earth, supervolcanos can release more than 1000 km ³ of lava and ash in a single eruption. The last known such eruption was the Yellowstone caldera 642 000 years ago that covered half of the continental US in ash. Bleacher and Michalski examined orbital images of Arabia Terra to try to explain its curious features. The crater-like areas could have been impact craters but they lack the usual halos of ejected material. And the area lacks volcanic peaks but has a layer of high-sulfur-content material that could not have been deposited from volcanos farther away. The researchers determined that if the craters were formed by supervolcanos, that would explain the lack of other volcanos and the high-sulfur-content layer. By their estimates the two eruptions each created between 4600 km3 and 7200 km ³ of ash.