crust of Mars remains fixed over a stationary hotspot, and a volcano can continue to discharge lava until it reaches an enormous height.

Being a shield volcano, Olympus Mons has a very gently sloping profile. The average slope on the volcano's flanks is only 5%. Slopes are steepest near the middle part of the flanks and grow shallower toward the base, giving the flanks a concave upward profile. Its flanks are shallower and extend farther from the summit