The Magnificent structure that is Olympus Mons
Being the largest volcano in the Solar System at 27KM above the mean surface level, Olympus Mons is among the most interesting of Martian features, and has therefore raised many questions about how it came to be. The giant shield volcano is located on the Tharsis Rise; a swelling 4000KM across with a maximum elevation of 10KM. Olympus Mons’ huge 550KM diameter is symbolic of its effusive volcanic eruptions most likely helped by larger eruption rates and lower gravity.
Its size is incomparable in the Solar System, being over 2.5 times the total elevation of Mauna Kea on Hawaii, which is one of the largest terrestrial volcanoes. A highly important factor in its size is the lack of Martian plate tectonics. On Earth, volcanic chains are formed when a tectonic plate floats over a stationary hot spot deep in the mantle, generating magma under the crust. This automatically restricts the size of a terrestrial volcano as the tectonic plate drags away the initial formation, creating another volcano in its wake. The Martian surface is unmoving however, meaning that the size of Olympus Mons could be due to its position on the surface over a stationary hot spot.
At the summit of the volcano there are 6 calderas which are symbolic of the volcanoes active nature. These calderas can be chronologically dated as they overlap, but what is truly outstanding is their size; the overall caldera complex is 85KM long, 60KM wide, and reaches up to 3KM deep. Given that a caldera is formed from the collapse of overburden rock into the newly empty magma chamber below, this can give us an indication into the size of the magma chambers, and consequently the volume of lava expelled from them.
The shield nature of Olympus Mons is due to the viscosity of the lava being very low, so it flows easier over the contours on the Martian surface; thus being able to travel further than if the lava were of a higher viscosity. The highly fluid lava has been flowing far from volcanic vents creating a very shallow slope volcano.
Olympus Mons is mostly surrounded by an escarpment that sets it above the surrounding terrain by a maximum height of 6KM. Imagery taken by the Mars Express orbiter in 2004 of the lava flows visible on the scarp of the volcano reveals that the volcanic rock can be dated between 115 and 2 million years, meaning that this volcano has been active for 113 million years a largely significant amount of time. In addition to its lengthy period of activity, it may not yet be over; 2 million years is not that long ago in a geological respect, indicating that this volcano may still be active wouldn’t that be an amazing sight to see on Mars?
Further exploration and research into the geological history of the Red Planet’ may give important information about Mars’ evolution, and what we could expect from it in the future. It was clearly once a very active planet (symbolic from many other volcanoes in addition to Olympus Mons), and its last activity was in the not-so-distant geological past, so can it be active again?
Mars isn’t presently famous for it’s highly dynamic surface, but a little more research into this giant feature could reveal that some action may be nearing either way, I don’t think anyone will get bored of studying the largest volcanic body known to mankind, and something tells me that the scientific community may not be able to rest until someone has experienced its enormous dimensions in reality…
