This Absolute Natural Colors image of Jupiter's "restless" Volcanic moon Io shows the Topography of a Region that includes the Zal Patera and a Mountain, or Plateau, that borders it to the West. This view was created by combining two different frames taken by the NASA - Galileo spacecraft on November 25, 1999 and on February 22, 2000.
As we mentioned hereabove (as well as in yesterday's APOD), a Mountain that is approx. 120 Km (such as about 75 miles) wide rises to the West of the Patera, which appears to us as a Dark Volcanic Depression. By measuring the shadow cast by this Relief, the Galileo Scientists were able to determine that the Eastern Margin of this Plateau is about 1,5 Km (approx. 5000 feet) high.

To the West and North/West, the Mountain's Margins are "Scalloped", and such a fact is a strong evidence that a process called "Sapping" might still be in-process and causing their massive erosion. Sapping occurs when a Fluid Material (i.e.: Lava or Water) escapes from the base of a Cliff, causing the material above it to collapse. Along the North/Western Margin, the rough material visible at the base of the Cliff could well be debris left over from the Sapping Process.

Last, but not least, some Dark Lava Flows can be seen coming from a Fissure positioned to the East of the Mountain.
The Galileo Scientists are in the process of generating Topographic Maps from these images, and such Maps may help them to reveal the Heights and Slopes of the different Landforms located in this Region (however, it will be a VERY hard task to also determine the strength as well as the physical and mineralogical properties of Io's Surface Materials).

The aforementioned Maps may also be useful in understanding the processes of Uplift and Erosion which, almost continuously, keep occurring on Io.
The picture is centered at 42,3° North Latitude and 76,9° West Longitude. North is towards the top of the picture. The frames used to create this image were at ranges of approx. 26.000 and 33.500 Km (such as about 16.200 and 20.900 miles) from Io. The resolution of this image is about 335 meters per Picture Element (---> Pixel).

This frame has been colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Galileo Spacecraft and then looked down, towards the Zal Patera Region, located on the Jovian moon Io), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.