The scale of a volcano can be difficult to comprehend, as they represent millions of years of accumulated material that shapes entire landscapes. Identifying the single “biggest” volcano is complicated because the title depends entirely on the specific method of measurement used. This often leads to confusion between the tallest mountains and the most massive structures. To definitively answer which volcano holds the global record, a standard of comparison must first be established.
Defining the Metrics of Size and Activity
Geologists employ various metrics to assess a volcano’s size, making the term “biggest” ambiguous. The most common way to measure overall magnitude is by total volume and mass, which quantifies the total amount of rock it contains. This volumetric measurement is considered the standard for claiming a volcano is the absolute largest on the planet. Other measurements include height above sea level and total height from the base to the summit, often measured from the ocean floor.
A volcano’s status as “active” is defined by specific criteria, not continuous eruption. Generally, a volcano is classified as active if it has erupted within the Holocene epoch (the last 10,000 years) and is likely to erupt again in the future. This classification separates currently erupting mountains from those that are dormant or extinct. Understanding these distinct metrics is necessary to interpret the record holder.
Identifying the Largest Active Volcano
When measured by total volume and mass, the undisputed largest active volcano in the world is Mauna Loa, located on the island of Hawaiʻi. This colossal shield volcano holds the record due to the sheer amount of material it contains, which extends far beneath the ocean surface. Mauna Loa’s estimated volume is at least 75,000 cubic kilometers (18,000 cubic miles). This measurement accounts for the entire structure from its base on the seafloor to its summit, confirming its status as the most massive active volcanic edifice on Earth.
Geological Profile and Eruptive History
Mauna Loa is classified as a shield volcano, recognizable by its broad, gently sloping profile. This shape results from its highly fluid, low-viscosity basaltic lava flows, which travel great distances before solidifying. The volcano is one of five that form the Island of Hawaiʻi, and its massive bulk makes up more than half of the island’s surface area. Its formation is tied to the movement of the Pacific Plate over a stationary mantle hotspot, a process distinct from volcanoes formed at tectonic plate boundaries.
While the summit of Mauna Loa reaches 4,169 meters (13,677 feet) above sea level, this figure only tells a fraction of its story. Its submarine flanks descend five kilometers to the ocean floor, which is depressed an estimated eight kilometers by the volcano’s massive weight. This gives it a total height from the ocean floor to its peak of roughly 17 kilometers (10.5 miles), a scale that dwarfs even the highest continental mountains. The volcano has erupted 33 times since its first reliably recorded event in 1843.
Its eruptions are typically effusive rather than explosive, meaning the lava flows out gently. The most recent eruption occurred in November 2022, after a 38-year period of quiescence. Activity began in the summit caldera and migrated to the Northeast Rift Zone. This recent activity reaffirms its standing as an active volcano. Monitoring by the Hawaiian Volcano Observatory tracks seismic activity and ground deformation, which are indicators of magma movement beneath the surface.
Notable Contenders and Record Holders
The question of the “biggest” volcano often introduces other contenders that hold distinct records. Ojos del Salado, located on the border of Chile and Argentina, holds the title of the world’s highest active volcano above sea level, with a summit reaching 6,893 meters (22,615 feet). Although taller than Mauna Loa when measured from sea level, its total volume is far less substantial. This difference highlights the distinction between height and overall mass.
Other immense volcanic features, such as the Tamu Massif in the Pacific Ocean, were once considered candidates for the largest single volcano by volume. However, the Tamu Massif is extinct, having formed about 145 million years ago. Recent research suggests it may be an oceanic plateau formed by seafloor spreading rather than a single shield volcano. Mount Sidley in Antarctica, while the continent’s tallest volcano, is considered dormant and lacks the ongoing activity required for the “largest active” title. Mauna Loa’s combination of immense volume and documented recent activity secures its position as the world’s largest active volcano.