Tharsis is a volcanic bulge on the equator, several thousand kilometers across and several kilometers high. Three giant shields, Ascraeus Mons, Pavonis Mons, and Arsia Mons, line up across it. They are the Tharsis Montes. Each is a shield in its own right, and each is smaller than Olympus Mons, which sits off the bulge to the northwest.
The rise is heavy enough to have warped the crust around it. The opening of Valles Marineris on the eastern flank is the clearest tectonic answer to that load. NASA's public facts treat this volcanic ground, and the canyon beside it, as part of the planet's basic description. [1]
A province, not one mountain
Lava plains bury older craters across a region the size of a continent. The three aligned montes likely grew above long-lived conduits. Pavonis sits near the equator. Ascraeus is the northern one, Arsia the southern. Their summit calderas are visible from orbit.
Olympus Mons is usually grouped with the Tharsis volcanic province even though it stands apart from the three. Geography of Mars treats the whole rise as one of the planet's first-order features.
What the load did
Adding that much rock shifted stress through the lithosphere. Fractures radiate and circle the rise. Valles Marineris is the largest opening, but it is not the only one. The geography of Mars is partly the geography of this one province.
Engineering screen
A summit this high is a poor match for a heavy lander, because the air column is short. Site dossiers does not store a surveyed summit elevation and does not score the province. The 22 km figure on Olympus Mons and on Pressure and the areoid is a round screen.
See also
What links here
References
- NASA Science. Mars: Facts. Tharsis volcanoes and Valles Marineris. https://science.nasa.gov/mars/facts/