In this beautiful VIS image, taken by the NASA - Mars Odyssey Orbiter on February, 5th, 2004, and during its 9.509th orbit around the Red Planet, we can see a small portion of the the Edge of the North/Western Flank of the Martian Volcano known as Tyrrhenus Mons.
Tyrrhenus Mons, formerly known as Tyrrhena Mons or even Tyrrhena Patera, is a large Volcano located in the Mare Tyrrhenum Quadrangle of Mars, and centered at 21,36° South Latitude and 253,47° West Longitude. The name "Tyrrhena Patera" now refers only to its Central Depression (such as the Volcanic Crater, or Caldera). Even this Volcanic Surface Feature of Mars was so named after a "Classical Albedo Feature".
Several Pit Chains (unfortunately, not visible here) are found at the Summit of Tyrrhenus Mons. They were formed by collapse of Rocks and Dust into underground voids (---> Caverns and Tunnels, maybe). Since these Pits formed both Chains and Concentric Fractures that are basically aligned, they are probably the visible consequence of an extension (---> caused by Stress) of the Surface.
Volcanic Processes made the Crust pull apart and several Voids were formed in the underground; then, the aforementioned Material fell into them, leaving holes on the Surface. Tyrrhenus Mons is one of the oldest Volcanoes of Mars and, as a consequence of its old age, Tyrrhenus Mons has many Radiating Gullies on its Slopes. When it was formed, Magma may have gone through Frozen Ground and then eruped. In time, it was easily eroded Ash, instead of Lava Flows.
Latitude (centered): 20,2209° South
Longitude (centered): 104,9560° East
This image (which is an Original Mars Odyssey Orbiter falsely colored and Map-Projected frame published on the NASA - Planetary Photojournal with the ID n. PIA 19749) has been additionally processed, magnified to aid the visibility of the details, contrast enhanced and sharpened, Gamma corrected and then re-colorized in Absolute Natural Colors (such as the colors that a normal human eye would actually perceive if someone were onboard the NASA - Mars Odyssey Orbiter and then looked down, towards the Surface of Mars), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.