Why did volcanoes on Mars form where they did?

Answer 1

Early in its life Mars wasn't all too different from Earth. Most volcanoes on Earth form through tectonic activity (movement of crustal plates over the mantle), especially subduction. When an oceanic and continental plate collide, it sends the denser oceanic plate down toward the mantle, causing pressure that melts the rock into magma, eventually resulting in a volcano on the surface. Presumably the same or similar kinds of processes led to the development of the volcanoes on Mars. When we see volcanoes on Mars, its safe to assume they may have formed where they did because of the movement of Mars' continental and oceanic plates while the planet still had an active core.

Answer 2

Volcanoes on Mars formed where they did due to the planet's unique geological features, such as hot spots or weak spots in the crust. The Tharsis region, for example, is home to some of the largest volcanoes in the solar system, likely due to upwelling magma from deep within the planet. Other regions, like Elysium Mons, may have formed over a mantle plume similar to those on Earth.