This helps explain why concentrations of mountains are seen on Io that are separated from concentrations of volcanoes. The researchers propose that similar events may have occurred on Europa, another satellite of Jupiter, and the early Earth. Images taken by NASA's Galileo spacecraft with different angles of sunlight help scientists interpret the three-dimensional shape of structures on Jupiter's moons. This pair shows a mountain named Tohil Mons on the innermost of Jupiter's four large moons, Io. The top image was taken at low resolution and a low Sun angle during Galileo's third orbit, in 1996.
Labels indicate the peak of the mountain and two volcanic depressions, called paterae.
This image was released Monday by JPL, not the authors of the research discussed in this story. Io's surface is dotted with active volcanoes spewing plumes of sulfurous gas and emitting vast streams of scorching lava. These are compressive stress, due to the general movement or sinking of the crust closer to Io's center, and thermal stress, which is generated when regions of cool crust suddenly become heated. The combination of compressive and thermal stresses breaks up the crust and produces irregular, or chaotic, distributions of mountain peaks. Slight changes in the rate of lava flow from Io's mantle and the heating of cooler crust below the surface create the mountain-forming faults, McKinnon said.