Alba Mons - Location and Size

Location and Size

Alba Mons is centered at { {Coord|40.47|N|250.4|E|globe:Mars}} in the Arcadia quadrangle (MC-3). Much of the volcano's western flank is located in the adjacent Diacria quadrangle (MC-2). Flows from the volcano can be found as far north as 61°N and as far south as 26°N (in the northern Tharsis quadrangle). If one takes the outer margin of the flows as the volcano's base, then Alba Mons has north–south dimensions of about 2,000 km (1,200 mi) and a maximum width of 3,000 km (1,900 mi). It covers an area of at least 5.7 million km2 and has a volume of about 2.5 million km3. The volcano dominates the northern portion of the Tharsis bulge and is so large and geologically distinct that it can almost be treated as an entire volcanic province unto itself.

Although Alba Mons reaches a maximum elevation of 6.8 km (22,000 ft) above Mars’ datum, the elevation difference between its summit and surrounding terrain (relief) is much greater on the north side of the volcano (about 7.1 km (23,000 ft)) compared to the south side (about 2.6 km (8,500 ft)). The reason for this asymmetry is that Alba straddles the dichotomy boundary between the cratered uplands in the south and the lowlands to the north. The plains underlying the volcano slope northward toward the Vastitas Borealis, which has an average surface elevation of 4.5 km (15,000 ft) below datum (-4.500 km (14,760 ft)). The southern part of Alba Mons is built on a broad, north-south topographic ridge that corresponds to the fractured, Noachian-aged terrain of Ceraunius Fossae (pictured left).