Ring of Fire
Here is a color view of the southern part of the Caloris basin. Extending along the southern rim are a number of pyroclastic deposits that have a distinctive reddish color. The inset locator map shows the entire Caloris basin; the red dots correspond to mapped pyroclastic deposits, which formed during explosive volcanic eruptions. On the Earth, volcanoes are often associated with boundaries where tectonic plates interact. The Pacific "Ring of Fire" is a famous example of volcanism found at plate boundaries. Mercury, by contrast, is a one-plate planet. Instead, mercurian volcanism is largely controlled by fracturing or tectonic features related to impact basins and craters. Caloris's southern rim is a partial "ring of fire."
Date acquired: January 9, 2013
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington