After a six-year effort, researchers have released the first geologic map of the solar system's most volcanically active object, Jupiter's moon Io.

The colorful and highly detailed map, published Monday by the U.S. Geological Survey, shows off Io's hellish features. It identifies 425 volcanoes as well as lava flow fields, squat mountains, deposits left by volcanic plumes, and plains rich with sulfur dioxide.

"This map enabled us to recognize the variety of volcanic and tectonic features on the surface of Io to a greater degree than ever before," wrote planetary scientist David Williams of Arizona State University, who led the team producing the map, in an e-mail to Wired.

With this information, researchers can not only develop and test models about Io's interior, but also better understand the formation of volcanoes and mountains on it surface.

Io owes its geologic activity to interactions with its neighbors. Gravitational forces from Jupiter and its sister moons, Europa and Ganymede, stretch and flex Io's thin crust. This generates roughly 25 times the volcanic activity found on Earth.

The new map combined images from NASA's two Voyager flybys of the 1970s as well as images from the Galileo orbiter, which circled Jupiter from 1995 to 2003. Because the moon's surface changes constantly from new eruptions, however, researchers will need to rely on telescopes from Earth to note any bright outbursts associated with volcanic eruptions.

Io is a very alien world. The incessant reworking of the moon's face means that it lacks a feature common on most other bodies in the solar system: craters. Impacts of large meteorites, for example, are soon wiped clean by lava flows and other volcanic processes.

Also lacking on Io are Earth-like volcanic mountains, such as Mt. St. Helens or Mt. Fuji. Instead, Io boasts large lava flow fields and lava lakes confined in volcanic craters.

The reason for Io's missing mountains is that the moon is deficient in silica-rich volcanic materials that produce steep cinder cones, Williams says. Io’s lavas are instead very rich in magnesium, very hot, very fluid and are much more likely to form shallow lava flow fields.

"Studying Io's lavas are like looking into a mirror of the ancient Earth; that is, seeing the way volcanoes on Earth formed billions of years ago," Williams wrote.

Images: USGS