Arsia Mons

The Arsia Mons is a shield volcano in the Tharsis region of Mars and one of the three Tharsis Montes, which were first observed in 1971 by the space probe Mariner 9. With a base diameter of 350 km and 14 km altitude, it is the volume after the second-largest known volcano. The air pressure at the top is below 107 Pascal. As the entire chain of Tharsis Montes, as well as the Arsia Mons is extinct for 100 million years. The unusual size of these shield volcanoes probably goes back to the fact that there are no plate tectonics on Mars; the crust so do not passes over the hotspot. Instead of a chain of volcanoes thus suffers a massive shield volcano. Cause of the strong volcanic activity in the past, it may have been an impact event - possibly the same one that the vast basin Hellas Planitia formed on the opposite side of the planet.

The wide caldera that originated in the collapse of the emptied magma chamber has a diameter of 110 km and annually offers space for cyclonic dust storms that are caused by warm air rising in the southern Martian hemisphere before the winter on the flanks of the mountain and dust particle carries with it. The above the Caldera towering spiral cloud can reach heights of 15-30 km - a phenomenon that is not observed in the other volcanoes of the Tharsis region.

The flanks of the Arsia Mons are particularly marked along a north to south by the volcanic cone withdrawing weakness zone of large-scale collapse structures. Current up to 2 km deep Grikes probably originated as extensive lava flows initially only on the surface aushärteten, while the molten rock in the underlying cavity continued to flow. Later, the so- formed cavities collapsed together. 2007 discovered the Spacecraft 2001 Mars Odyssey and Mars Reconnaissance Orbiter further geological structures - the so-called Seven Sisters on the slopes of the volcano. These dark spots with 100-250 m in diameter are interpreted as cave entrances. Whether it is just about vertical chimneys or additions to stretched cavities, but for the time being must remain speculation. Hopes that primitive ecosystems could have developed in the caves are probably classified as unrealistic because of the extreme altitude climate.