The widest volcano in the solar system — flat as a shield, vast as a nation.
Alba Mons sprawls roughly 1,600 km across the northern edge of the Tharsis rise, dwarfing every other volcano in footprint. Yet it stands only about 6.5 km tall, so its flanks slope by mere fractions of a degree.
Claim your plot here →Alba Mons is a volcanic giant unlike any other. While Olympus Mons is famous for height, Alba wins on sheer spread — its lava flows and fracture systems reach some 1,600 km end to end, an area larger than that of any terrestrial volcano. Its extreme flatness likely reflects very fluid, low-viscosity lava and possibly eruptions influenced by ground ice.
The mountain is ringed by concentric fractures and graben, including the Alba Fossae and Tantalus Fossae, carved as the crust flexed under the load and stress of the Tharsis bulge. Long, branching lava channels lace its flanks, recording repeated effusive eruptions over hundreds of millions of years during the Hesperian period.
Olympus is far taller, but Alba covers a much larger area — a low dome the size of the western United States.
No volcano on Earth comes close in footprint; Alba's spread would blanket a large European country.