Types of Volcanoes

Stratovolcanoes (also called composite volcanoes) are tall, conical mountains built by alternating layers of lava flows, volcanic ash, and tephra. They are the most iconic and often the most dangerous type of volcano, responsible for some of history's most devastating eruptions. Famous examples include Mount Fuji, Vesuvius, and Mount St. Helens.

Shield volcanoes have broad, gently sloping profiles built almost entirely from fluid basaltic lava flows. They are among the largest volcanoes on Earth by volume. Unlike stratovolcanoes, shield volcanoes rarely produce explosive eruptions — instead, lava flows steadily from vents and fissures, building up the characteristic dome shape over time.

Calderas are large volcanic depressions formed when a volcano collapses after a massive eruption empties the magma chamber below. They can span tens of kilometers in diameter and often fill with water to form crater lakes. Some of the world's most powerful eruptions have come from caldera-forming events, including Yellowstone, Krakatau, and Santorini.

Volcanic fields consist of clusters of small volcanic vents — typically cinder cones, maars, and lava flows — spread across a wide area rather than concentrated in a single large edifice. They form when magma reaches the surface through many small openings in the crust. Fields can cover hundreds of square kilometers and remain active for millions of years.

Lava domes are rounded, steep-sided mounds formed when viscous lava erupts slowly and piles up around the vent rather than flowing far downslope. The thick, pasty magma often plugs the vent, building pressure that can lead to sudden explosive eruptions and pyroclastic flows. Lava domes are commonly found within the craters of larger stratovolcanoes.

Complex volcanoes are volcanic centers that do not fit neatly into a single category. They often feature multiple vents, overlapping structures, and varied eruption styles. A complex volcano may include elements of stratovolcanoes, calderas, lava domes, and fissure vents all within the same volcanic system, reflecting a long and varied eruptive history.

Fissure vents are linear cracks in the Earth's surface from which lava erupts. Rather than building a cone, they produce curtains of fire and extensive lava flows that can cover vast areas. Iceland's volcanic landscape is dominated by fissure eruptions, including the 2023 Sundhnuks eruptions on the Reykjanes Peninsula and the historic 1783 Laki eruption.

Pyroclastic cones (including cinder cones and scoria cones) are the simplest type of volcano — small, steep-sided hills built from fragments of solidified lava ejected from a single vent. They rarely exceed 300 meters in height and often form during brief eruptions lasting weeks to months. Many volcanic fields contain dozens or hundreds of pyroclastic cones.

Maars are broad, shallow craters formed by explosive eruptions caused when rising magma encounters groundwater. The resulting steam explosions blast out a wide crater surrounded by a low rim of ejected debris. Maars are often filled with water to form circular lakes and are among the most common volcanic landforms on Earth.

Tuff cones are volcanic cones built from consolidated volcanic ash (tite) that accumulates around a vent during hydrovolcanic eruptions. They are steeper and more consolidated than cinder cones, formed when magma interacts with water near the surface. Diamond Head in Hawaii is one of the world's best-known tuff cones.

Lava cones are small volcanic edifices built almost entirely from lava flows rather than pyroclastic material. They have smoother slopes than cinder cones and are typically composed of more fluid basaltic lava. Lava cones are relatively uncommon compared to other volcanic landforms.

Crater-type volcanoes feature prominent explosion craters that dominate the volcanic landform. These craters are formed by explosive eruptions that excavate rock and debris, leaving behind a bowl-shaped depression. Rows of aligned craters often mark underlying tectonic faults.

Some volcanoes have uncertain or unclassified morphologies. These may be poorly studied, heavily eroded, or transitional between recognized types. As volcanic research advances, many of these volcanoes may be reclassified into established categories.