Olympus Mons: The Largest Volcano in Our Solar System

Mind-Boggling Dimensions

The statistics of Olympus Mons are almost incomprehensible:

If you were standing at the base of Olympus Mons, the volcano would extend so far in every direction that you couldn't see its edges - it would disappear beyond the horizon due to Mars's curvature.

Why Is Olympus Mons So Massive?

The key to understanding Olympus Mons's extreme size lies in what Mars lacks: plate tectonics.

On Earth, the crust is divided into moving plates. Volcanic hotspots (like the one beneath Hawaii) remain stationary while the plate above them moves. This creates chains of volcanoes, each active for only a relatively brief geological period before being carried away from the magma source.

Mars has no such plate movement. The Martian crust is a single, stationary shell. This means the volcanic hotspot beneath Olympus Mons has been feeding lava to the same location for billions of years, allowing the volcano to grow to staggering proportions.

Additionally, Mars's lower gravity (about 38% of Earth's) allows volcanic structures to grow higher before collapsing under their own weight.

A Shield Volcano Like Hawaii

Olympus Mons is classified as a shield volcano, named because of its broad, gently sloping shape resembling a warrior's shield lying on the ground.

Shield volcanoes form from eruptions of low-viscosity basaltic lava that flows easily over long distances. This creates wide, shallow slopes typically between 2° and 5°. Hawaii's Mauna Loa is Earth's largest shield volcano, but Olympus Mons dwarfs it by every measure.

Is Olympus Mons Still Active?

Scientists classify Olympus Mons as dormant rather than extinct. Analysis of lava flows on its flanks suggests the most recent eruption occurred approximately 25 million years ago - recently in geological terms.

This means future eruptions are theoretically possible, though Mars shows no current signs of volcanic activity. If Olympus Mons were to erupt again, the lava flows could extend hundreds of kilometers across the Martian surface.

The Dramatic Cliff Escarpment

One of Olympus Mons's most striking features is the massive cliff that surrounds its base. This escarpment rises 6 to 8 kilometers in many places - nearly as tall as Mount Everest itself.

Scientists believe this cliff formed through a combination of erosion and collapse events. The sheer vertical walls make Olympus Mons appear to sit on a raised platform, further emphasizing its dominance over the surrounding terrain.