Olympus Mons – The Largest Volcano in The Solar System
Olympus Mons (latin for Mount Olympus) is a very large shield volcano on the planet Mars. The volcano has a height of over 21 km (13.6 mi or 72,000 ft) as measured by the Mars Orbiter Laser Altimeter (MOLA). Olympus Mons is about two and a half times Mount Everest’s height above sea level. It is one of the largest volcanoes, the tallest planetary mountain, and the second tallest mountain currently discovered in the Solar System.
It is often cited as the largest volcano in the Solar System. However, by some metrics, other volcanoes are considerably larger. Alba Mons, northeast of Olympus Mons, has roughly 19 times the surface area, but is only about one third the height. Pele, the largest known volcano on Io, is also much larger, at roughly 4 times the surface area, but is considerably flatter.
Additionally, Tharsis Rise, a large volcanic structure on Mars of which Olympus Mons is a part, has been interpreted as an enormous spreading volcano. If this is confirmed, Tharsis would be by far the largest volcano in the Solar System. Olympus Mons is the youngest of the large volcanoes on Mars, having formed during Mars’s Hesperian Period. It had been known to astronomers since the late 19th century as the albedo feature Nix Olympica (Latin for “Olympic Snow”). Its mountainous nature was suspected well before space probes confirmed its identity as a mountain.
Olympus Mons is the result of many thousands of highly fluid, basaltic lava flows that poured from volcanic vents over a long period of time (the Hawaiian Islands exemplify similar shield volcanoes on a smaller scale – see Mauna Kea). Like the basalt volcanoes on Earth, Martian basaltic volcanoes are capable of erupting enormous quantities of ash. Due to the reduced gravity of Mars compared to Earth, there are lesser buoyant forces on the magma rising out of the crust. In addition, the magma chambers are thought to be much larger and deeper than the ones found on Earth.