See also: volcanic explosivity index.


This entry concerns shield volcanoes, which are what most people think of when they think of eruptions: Mount Fuji, Mauna Loa, Mount Etna and so on. However, eruptions, including extremely massive eruptions, may produce other features, such as the Siberian Traps and the Deccan Traps.

Largest volcanoes

The largest known volcano on Earth is Tamu Massif, but its peak is about 2 kilometers below the surface of the northwest Pacific Ocean (about 1500 kilometers east of Japan, at about 158°E, 33°N). It covers around 120,000 square miles, roughly the size of the state of New Mexico. From base to peak is about 6 km, but the base being so wide, the slope is extremely shallow.

Although reseachers had been aware of Tamu Massif for decades, not until 2013 did core samples and seismic data provide enough evidence to conclude that Tamu Massif was a single volcano, with a single vent, and not a conglomeration of separate, neighboring volcanoes.┬╣

The largest visible volcano on Earth is Mauna Loa, which forms about half of the island of Hawaii. Its height, from the sea floor to its summit, is about 10 kilometers (6.3 miles) and its diameter is 120 km (75 miles). It covers about 2000 square miles, and is still growing.

photo of Olympus Mons overlaid with outline of the state of Arizona

Olympus Mons, Mars

The largest known volcano in the Solar System is Olympus Mons, on the planet Mars. It is 25 kilometers high with a base approximately 624 km (374 miles) in diameter. Its volume is about 100 times that of Mauna Loa.  For an explanation of why volcanoes on Mars can be so much bigger than those on Earth, see the NASA web page at: 



1. William W. Sager, Jinchang Zhang, Jun Korenaga, Takashi Sano, Anthony A. P. Koppers, Mike Widdowson and John J. Mahoney,
An immense shield volcano within the Shatsky Rise oceanic plateau, northwest Pacific Ocean.
Nature Geoscience (rev. online 6 Sept. 2013)

Largest eruptions

The largest known observed volcanic eruption in the Solar System occurred on Io, a moon of Jupiter, on 22 February 2001.  The eruption covered 1900 square kilometers.┬╣

Eruption When Volume of Rock and Ash Ejected,
cubic kilometers┬▓
Mount St. Helens (USA) May 1980 3
Pinatubo (Phillipines) 1991 7
Tarawera (NZ) ~1400? 7.5
Krakatoa (Indonesia) 1883 8
Rotoiti Breccia (NZ) 65,000 tears ago 50
Taupo Pumice (NZ) 1800 years ago 110
Mamaku Ignimbrite (NZ) 220,000 yrs ago 200

1. Franck Marchis, Imke de Pater, A. G. Davies, H. G. Roe, T. Fusco, D. Le Mignant, P. Descamps, B. A. Macintosh, and R. Prangé.
High-resolution Keck adaptive optics imaging of violent volcanic activity on Io.
Icarus, volume 10, number 1 (November 2002), pages 124-131.

2. Sources: Bruce Houghton and Bradley Scott, Geyserland, Geological Society of New Zealand Guidebook #13, 2002; 


For many years the University of North Dakota has maintained an excellent website on volcanoes: volcano.und.edu

Richard V. Fischer et al.
Volcanoes: Crucibles of Change.
Princeton University Press, 1998.

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