Maat Mons is displayed in this three-dimensional perspective view of the surface of Venus, with the vertical scale multiplied by 22.5. Based on Magellan probe radar images
Maat Mons is a massive shield volcano. It is the second-highest mountain, and the highest volcano, on the planet Venus. It rises 8 kilometres (5.0 mi) above the mean planetary radius at , and nearly 5 km above the surrounding plains. It is named after the Egyptian goddess of truth and justice, Ma'at.
A chain of small craters 3–5 km in diameter extends some 40 km along the southeast flank of the volcano, but rather than indicating a large fissure eruption, they seem to also be formed by collapse: full resolution imagery from the Magellan probe reveals no evidence of lava flows from these craters.
At least two large scale structural collapse events seem to have occurred in the past on Maat Mons.
Intriguingly for planetary geologists, atmospheric studies carried out by the Pioneer Venus probes in the early 1980s revealed a considerable variation in the concentrations of sulfur dioxide (SO2) and methane (CH4) in Venus' middle and upper atmosphere. One possible explanation for this was the injection of volcanic gases into the atmosphere by plinian eruptions at Maat Mons.
Although many lines of evidence suggest that Venus is likely to be volcanically active, present-day eruptions at Maat Mons have not been confirmed.
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- Robinson, Cordula A.; Thornhill, Gill D.; Parfitt, Elisabeth A. (1995). "Large-scale volcanic activity at Maat Mons: Can this explain fluctuations in atmospheric chemistry observed by Pioneer Venus?". Journal of Geophysical Research 100 (E6): 11755–11763. Bibcode:1995JGR...10011755R. doi:10.1029/95JE00147.