Arsia Mons

Today's VIS image shows a cross section of the western side Arsia Mons, from the rim of the summit caldera at the top of the image, to the collapse features at the bottom of the image. A large volcanic crater known as a caldera is located at the summit of all of the Tharsis volcanoes. These calderas are produced by massive volcanic explosions and collapse. The three large aligned Tharsis volcanoes are Arsia Mons, Pavonis Mons and Ascreaus Mons (from south to north). There are collapse features on all three volcanoes, on the southwestern and northeastern flanks. This alignment may indicate a large fracture/vent system was responsible for the eruptions that formed all three volcanoes. The scalloped depressions and lines of craters are most likely created by collapse of the roof of lava tubes. Lava tubes originate during eruption event, when the margins of a flow harden around a still flowing lava stream. When an eruption ends these can become hollow tubes within the flow. With time, the roof of the tube may collapse into the empty space below. The tubes are linear, so the collapse of the roof creates a linear depression. In this region, the complexity of the collapse and faulting has created a unique surface. This region has collapse depressions with floors at a variety of elevations and depression sizes from small to large.

Arsia Mons is 450 km (270 miles) in diameter, almost 20 km (12 mi) high, and the summit caldera is 120 km (72 mi) wide. For comparison, the tallest volcano on Earth is Mauna Kea. From its base on the sea floor, Mauna Loa measures only 10.2 km (6.3 mi) high.