Using computer simulations, a team of researchers has created a model of the mountains of Io, Jupiter's innermost moon. These unique mountains are different than those seen on Earth, featuring isolated peaks that seem to come out of nowhere. Given the fresh coating of lava - approximately five inches a decade - that Io experiences, computer simulations are the best way to get a look at the moon's buried tectonic processes.
"The planetary community has thought for a while that Io's mountains might be a function of the fact that it is continuously erupting lava over the entire sphere," said William McKinnon of Washington University in St. Louis and senior author of the study. "All that lava spewed on the surfaces pushes downward and, as it descends, there's a space problem because Io is a sphere, so you end up with compressive forces that increase with depth."
In order to test this hypothesis, McKinnon used computer simulations.
"People have been squeezing planetary interiors forever to see what happens, but we're applying the squeeze differently, because on Io compression increases with depth; the surface is not in compression," he said. "We thought we could mimic this by beveling in the edges of a box, squeezing it as you might an accordion."
The simulations conducted by the Washington University researchers reveal how strains turn into faults deep in the lithosphere and make their way to the rock onto Io's surface and could explain why recent eruptions typically take place near mountains.
"It's a neat demonstration of how things might actually work," McKinnon said. "The compressive forces deep in the crust are incredibly high. When these faults breach the surface, those forces are released, and the entire stress environment around the fault changes, providing a pathway for magma to erupt."
Although the strange processes behind Io's mountain formations are unlike anything anywhere else in the solar system, McKinnon believes that it is possible that Earth was once like Io.
"The same kind of thing could have happened on Earth, when it was very young and entirely covered by a shallow ocean," he said. "Because there was still lots of volcanism, mountains like those on Io might have burst through the ocean. They might have been the first emergent land on Earth."
The findings were published in the May 16 issue of Nature Geoscience.
