An article published in the journal “Earth and Planetary Science Letters” describes a research about Arsia Mons, a volcano on the planet Mars. A team led by Jacob Richardson of NASA’s Goddard Space Flight Center examined high-resolution images taken by the MRO (Mars Reconnaissance Orbiter) space probe to determine that Arsia Mons was at its peak of activity about 150 million years ago and that its last activity probably ended about 50 million years ago.
Arsia Mons is located just south of the planet Mars’ equator and is part of the Tharsis Montes group together with Pavonis Mons and Ascraeus Mons. It’s a shield volcano, so named for its shape due to a very fluid lava that gets deposited farther than in other types of volcanoes that have a much denser lava. Arsia Mons’ caldera has a diameter of about 110 kilometers (68 miles) and the entire volcano has a diameter of about 435 kilometers (270 miles) and a height of about 20 kilometers (12 miles), making it the second Martian volcano in size after Olympus Mons.
Arsia Mons’ shield formed over billions of years but the details of its story are not yet clear. In its caldera 29 volcanic vents have been identified and in the course of this research Jacob Richardson’s team mapped the boundaries of lava flows for each of them to determine various characteristics. Each volcanic vent produced lava flows even tens of kilometers long and their age is probably one of the youngest on Mars since there are only relatively small craters in those lava flows.
The various information gathered was used to determine the volcano’s timeline using a new computer model specifically developed by the researchers. The number of craters is commonly used as a dating method because the more there are the oldest is the territory, in this case the lava flows. The researchers also applied other dating methods, for example based on stratigraphic information.
According to the results, the oldest lava flows date back about 200 million years ago while the most recent took place between 10 and 90 million years ago with a peak of probability around 50 million years ago. The peak of activity was found around 150 million years ago and at the time the volcanic vents in Arsia Mons’ caldera produced a total between 1 and 8 cubic kilometers of magma every million years which increased gradually the size of the volcano.
At the time of peak activity, Arsia Mons periodically created a new volcanic vent every 1 to 3 million years while on Earth in similar regions the volcanoes create a new volcanic vent every 10,000 years or so. Basically, there are similarities between the Arsia Mons’ history and that of Earth’s volcanoes but there are also many differences.
Understanding the life cycle of Martian volcanoes helps to better understand the history of Mars and the internal structure of the planet that originated that volcanic activity. Volcanoes such as Arsia Mons appear to have had an activity over a longer time span than Earth’s volcanoes and this new research helped to reconstruct that history.