Tharsis

Tharsis is a vast volcanic plateau centered near Mars’s western equator. It spans a large portion of the planet’s western hemisphere and stands as one of the most prominent topographic provinces on Mars. The region is defined by a massive load of volcanic material that has shaped the planet’s crust and gravity field over billions of years.

The area contains several of the planet’s largest volcanoes, including Olympus Mons, the tallest known volcano in the Solar System, and the three shield volcanoes known as the Tharsis Montes—Ascraeus Mons, Pavonis Mons, and Arsia Mons. The province also hosts numerous lava flows, calderas, and expansive volcanic plains, forming a broad and interconnected volcanic system.

Geologically, Tharsis records long-lived mantle volcanism that built up a substantial crustal load. This load contributed to tectonic uplift and stressed the surrounding crust, helping to create a network of large faults and fissures that culminates in the Valles Marineris canyon system along the region’s margins. The timing of the construction is debated, but volcanic activity in the Noachian to Hesperian periods—roughly more than 3.5 billion years ago—persisted for hundreds of millions of years.

Exploration data from orbiting missions, including Mars Global Surveyor and Mars Reconnaissance Orbiter, along with laser altimetry from the Mars Orbiter Laser Altimeter, have mapped Tharsis’s topography and deformation. These observations support ongoing studies of Mars’s volcanic history, crustal dynamics, and potential past climatic effects related to large volcanic episodes.

Tharsis remains a central reference point in the study of planetary volcanism and crustal evolution on Mars.