This image taken by Galileo on 16 October 2001 near Io's equator shows the contrast in volcanism styles found on Io. The central feature is a large patera, or volcanic depression, almost 100 kilometers (60 miles) long, that may have formed after eruptions of lava emptied its subsurface magma chamber and left an empty space into which the crust collapsed in an irregular fashion. Evidence of lava flows associated with this patera, however, is difficult to find. The flows have either been buried, or perhaps were never erupted and simply drained back deep into the crust.

On the right of the image is a small shield volcano, similar to the volcanoes of Hawaii. It is rare for lavas on Io to be thick enough to build shields around vents, they usually run out in thin, long flows instead. This shield also abuts some very pale lava flows that emerged from a small vent to the west. These flows could be made of sulfur, like the flows we've seen at Emakong Patera. The vent is also surrounded by dark, diffuse material, that may be the result of lava erupted in an explosive, gas-rich, "pyroclastic" eruption, similar to the Mount Saint Helens 1980 eruption. Every new region we explore on Io, we see the results of more extraordinary volcanic eruptions.

North is to the top of the image and the illumination is from the right. The image has a resolution of 330 m/pixel and is 340 kilometers across.

Image produced by: Zibi Turtle, Planetary Image Research Lab. (PIRL), Lunar and Planetary Lab. (LPL), University of Arizona

The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/images/io/ioimages.html.

NASA's Planetary Photojournal PIA-03532

May 28, 2002