Olympus Mons is a Martian shield volcano of epic proportions that can be seen through telescopes on Earth. It stretches an incredible 25 Km (15.5 miles) above sea level into the thin Martian atmosphere, three times the height of Mt Everest, towering well above the brutal dust storms of the planet.
The volcano is surrounded by 6 km high scarp (perimeter) at its base where ancient lava flows drape over the edges. It spans a ginormous 624 Km (374 miles) in width! To put this into perspective, that is the width of the state of Arizona and wider than the entire chain of Hawaiian islands.
Yet Olympus Mons is not the only large volcano on the planet, it is part of an area of volcanoes known as the Tharsis region. Spanning 4000 km across this region contains 12 large volcanoes all ranging between 10 – 100 times larger than any volcano found on Planet Earth.
The reason these large volcanoes exist is believed to be due to high volcanic activity. Concentrated stationary regions of rising mantle plumes known as hot spots transfer heat away from the planets interior and deliver lava to the surface. On Earth these hot spots can create chains of volcanic islands due to the movement of the planets tectonic crust. As the plates pass over the hot spot new volcanoes are formed and existing ones become extinct, revealing a distribution of lava over vast areas.
This is what formed the volcanic island chains of Hawaii.
On Mars, this is not the case. It is believed that ancient hot spots rose up from the mantle of the planet, but the crust did not move across them, resulting in a build-up of lava over billions of years forming huge structures.
Surface areas of the western scarp of this volcano have been dated to as little as 2 million years old, which in geological terms can be considered very recent. This suggests that the volcano may still be active, although at a much reduced rate due to the planets cooling interior.
There is much to learn about this intriguing and dynamic planet, we are just beginning.
In the words of the great Carl Sagan, “Mars is a world of wonders.”
Ankit Shah's Blog 