Exploring the Planets

Mars Volcanoes

Mars today has no active volcanoes. Much of the heat stored inside the planet when it formed has been lost, and the outer crust of Mars is too thick to allow molten rock from deep below to reach the surface.

But long ago, eruptions built enormous volcanoes and piles of thick ash. Volcanoes probably played a role in melting ice deposits, releasing floods of water onto the surface.

Skyscrapers of the Solar System

The crust of Mars is not broken up into moving plates as on Earth. So rising plumes of heated rock from deep below built gigantic volcanoes over many millions of years. Four of these giants formed on a bulge in the planet called the Tharsis Rise. Their peaks rise more than three times the height of Mount Everest, the tallest mountain on Earth.

Olympus Mons (left) is the largest volcano in the solar system. It stands 26 kilometers (15.5 miles) above the surrounding plains, and is 500 kilometers (300 miles) wide at its base.

Studies Courtesy of MOLA Science Team

Olympus Mons, Mars

Water-ice clouds, formed as moist air rises and cools, are almost a daily occurrence around Olympus and the four tallest other nearby volcanoes, Ascraeus Mons, Pavonis Mons, and Arsia Mons.

Mar Global Surveyor, MOC
NASA/JPL/Malin Space Science Systems image


Olympus Mons compared with the Hawaiian Islands. Despite its huge size, it displays very low relief when viewed from the side. If the Pacific crustal plate were not moving, the hotspot beneath the active volcanoes on the Big Island of Hawaii might have built an Olympus-sized volcano.

Comparison images courtesy of USGS and MODIS Land Rapid Response Team; oblique view courtesy of NASA/JPL/Malin Space Science Systems

Olympus Mons, Mars

The most recent lava flows that formed Olympus Mons spill over the steep scarp that surrounds its base. This scarp likely formed when parts of the volcano's flank collapsed and slid away.

Mar Global Surveyor, MOC
NASA/JPL/Malin Space Science Systems image

Lava Flow from Olympus Mons

A perspective view of part of the large scarp that surrounds the base of Olympus Mons.

Mars Express, High Resolution Stereo Camera
ESA image

Olympus Mons, Mars