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Why did Olympus Mons grow so much larger than volcanoes on Earth?
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Mars
An especially serene view of Mars (Tharsis side), a composite of images taken by the Mars Global Surveyor spacecraft in April 1999. The northern polar cap and encircling dark dune field of Vastitas Borealis are visible at the top of the globe. White water-ice clouds surround the most prominent volcanic peaks, including Olympus Mons near the western limb, Alba Patera to its northeast, and the line of Tharsis volcanoes to the southeast. East of the Tharsis rise can be seen the enormous near-equatorial gash that marks the canyon system Valles Marineris.
The tremendous size of Olympus Mons compared to volcanoes on Earth is primarily attributed to two factors: the stability of the Martian crust and a significantly longer period of accumulation, which may span more than a billion years.1
Unlike Earth, where plate tectonics constantly shift the crustâcausing volcanic chains to move away from their magma sources and limiting the size of individual volcanoesâMars lacks such a system. This tectonic stability allows a single volcanic vent to remain positioned over a stationary magma plume for an immense duration, enabling the volcano to grow to a massive scale through repeated eruptions of fluid basaltic lava.213