There are reams of volcanoes on earth. About 1900 of them are considered to be active. On Mars there exist about 22 volcanoes. None of them are active. Besides the two Martian major volcanic regions Tharsis and Elysium there are also volcanoes at Syrtis Major, Hesperia Planum and Malea Planum, the so-called Highland Volcanoes (Fig. 1). Volcanoes on Earth are typically located along plate boundaries all over the planet (Fig. 2). In opposite to the terrestrial case, the Martian volcanism is not ongoing. Crater counts revealed that most of the volcanism had stared in the early Noachian, about 4 Ga ago [Werner, 2006]. The age of the latest volcanic activity on Mars is dated on late Amazonian, about 100 Ma ago [Head et al., 2001; Werner, 2006].
The volcanoes at the two topographically dominating and morphologically distinct major volcanic provinces are characterized by morphologies which strongly correlate to the basaltic volcanic landforms on Earth [Werner, 2006]. Especially the Tharsis Volcanoes share many characteristics with the Hawaiian basaltic shield volcanoes [Carr, 1973]. The analogue images (Fig. 3 & 4) show Mauna Loa the second largest volcano of Hawaii (Fig. 3) and Olympus Mons at the Tharsis region (Fig. 4), the highest and most prominent volcano on Mars and even in the whole solar system. The right images show both volcanoes in a plan view and the left images show perspective views of the calderas. As most of the terrestrial volcanoes including Mauna Loa, Olympus Mons is a shield volcano consisting of a basaltic edifice. It has an elevation of more than 21 km and a width of about 640 km [Bleacher et al., 2007]. The summit caldera has a depth of about 3 km and a diameter of 60 x 90 km. Crater counts of the caldera floors reveal an age of 100 to 200 Ma [Neukum et al., 2004].
Mauna Loa is the largest active volcano on Earth with a height of 4170 m above the sea level. Its summit caldera has a dimension of 3 x 5 km elongated northeast-southwest and a depth of 183 m. The caldera is estimated to have collapsed 600-750 years ago [www2]. Despite the apparent similarity on the images, the main difference between the Martian and the terrestrial volcanoes are the greater size and the length of lows of the Martian volcanoes, mainly due to higher eruption rates. Another difference is the stationary character of the source of Martian volcanoes (no plate tectonics) and the lower gravity [Werner, 2006].
Last update: 07/06/2010 13:42
