Volcanoes are not all built the same way. Some form enormous mountains with gentle slopes, while others grow into steep cones, unstable lava domes, broad fissure systems or vast collapse depressions.
This guide explains the main types of volcanoes, how volcanic landforms are classified, what controls their shape and eruption style, and why some volcanoes behave very differently from others. It also connects to detailed guides about calderas, supervolcanoes, mud volcanoes, submarine volcanoes and seamounts.
How Are Volcanoes Classified?
Volcanoes are commonly classified by their shape, size, eruptive products, magma composition and the processes that created them. The visible landform is important, but it does not tell the whole story.
A single volcanic system may change over time. A broad lava-producing volcano can later develop a summit caldera, while a stratovolcano may grow lava domes, flank cones and multiple vents. Some regions contain overlapping volcanoes built during different eruptive periods.
Volcanologists examine several characteristics when identifying a volcano type:
- The shape and slope of the volcanic landform
- The number and arrangement of vents
- The composition and viscosity of the magma
- The proportion of lava flows, ash and other fragmented material
- The frequency and explosivity of eruptions
- The tectonic setting
- The presence of a crater, caldera, dome or fissure system
- The volcano’s long-term eruptive history
The categories below are useful, but nature does not always fit neatly into one label. Many volcanoes combine features of several types.
For the processes controlling magma composition, viscosity and eruption behavior, see Volcano Science Explained.
Shield Volcanoes
Shield volcanoes are broad volcanic mountains with gentle slopes. Their shape resembles a warrior’s shield lying on the ground, which is how they received their name.
They are built mainly by repeated eruptions of hot, fluid, low-viscosity lava. Because the lava can travel considerable distances before cooling, it spreads outward in thin layers and gradually creates an enormous volcanic structure.
How shield volcanoes form
Shield volcanoes usually develop through many eruptions from summit vents, flank vents and long fissures. Lava may flow through open channels or insulated lava tubes, allowing it to travel far from the eruption site.
Over time, thousands of overlapping lava flows build a wide mountain with slopes that are much gentler than those of a typical stratovolcano.
Typical magma and eruption style
Shield volcanoes are commonly associated with basaltic magma. Basaltic lava is generally hotter and less viscous than silica-rich magma, allowing gases to escape more easily.
Eruptions are therefore often effusive and may produce:
- Lava fountains
- Long lava flows
- Lava lakes
- Spatter cones
- Fissure eruptions
- Lava tubes
Shield volcanoes can still produce dangerous explosions, especially when magma interacts with groundwater, seawater or accumulated gas.
Hazards from shield volcanoes
The main hazard is often lava rather than widespread pyroclastic activity. Lava flows can bury roads, buildings, farmland and entire communities. Volcanic gases, earthquakes, ground cracking and crater collapse may also create serious risks.
Because some lava flows advance slowly, people may have time to evacuate. Infrastructure and property, however, may be impossible to protect.
Examples of shield volcanoes
- Mauna Loa in Hawaii
- Kīlauea in Hawaii
- Mauna Kea in Hawaii
- Skjaldbreiður in Iceland
- Fernandina in the Galápagos Islands
- Piton de la Fournaise on Réunion
Explore hotspot volcanism and the world’s largest shield volcanoes in Hawaiian Volcanoes & Hotspot Volcanism.
Stratovolcanoes
Stratovolcanoes are tall, steep-sided volcanoes built from alternating layers of lava, ash, pumice and other volcanic debris. They are also called composite volcanoes.
These are the classic cone-shaped volcanoes commonly shown in photographs, films and textbooks. Many of the world’s most famous and dangerous volcanoes are stratovolcanoes.
How stratovolcanoes form
Stratovolcanoes develop through repeated eruptions from a central vent or group of vents. Some eruptions release lava, while others produce explosive ash columns, pyroclastic flows or widespread tephra deposits.
The alternating accumulation of lava and fragmented material creates the layered structure reflected in the name “stratovolcano.”
Magma and eruption behavior
Stratovolcanoes commonly erupt andesitic, dacitic or rhyolitic magma, although basalt may also occur. These magmas can be more viscous than the fluid basalt typical of shield volcanoes.
Viscous magma can slow the escape of volcanic gases. Pressure may then build within the magma or behind material blocking the vent, increasing the potential for explosive eruptions.
Stratovolcano eruptions can produce:
- Ash columns
- Pumice falls
- Pyroclastic flows and surges
- Lava flows
- Lava domes
- Lahars
- Debris avalanches
- Lateral blasts
Why stratovolcanoes are dangerous
Stratovolcanoes can combine numerous hazards within the same eruption. Steep slopes promote landslides and fast-moving pyroclastic flows, while summit snow and ice can melt and produce lahars.
Some stratovolcanoes remain quiet for centuries, allowing large populations to grow around them before renewed activity begins.
A major flank collapse can suddenly remove pressure from the volcanic system and trigger a lateral explosion, as occurred during the 1980 eruption of Mount St. Helens.
Examples of stratovolcanoes
- Mount Fuji in Japan
- Mount St. Helens in the United States
- Mount Rainier in the United States
- Mount Vesuvius in Italy
- Mount Pinatubo in the Philippines
- Mount Merapi in Indonesia
- Popocatépetl in Mexico
- Mount Etna in Italy
Learn about the dangers associated with composite volcanoes in Volcanic Hazards Explained.
Cinder Cones
Cinder cones are small, steep-sided volcanoes built mainly from loose fragments of lava that fall around a vent. These fragments may include scoria, cinders, bombs and lapilli.
They are among the simplest and most common volcanic landforms.
How cinder cones form
Cinder cones commonly form during eruptions in which gas-rich magma is thrown into the air as incandescent fragments. The material cools and falls around the vent, gradually building a cone with a bowl-shaped summit crater.
The cone’s slope is controlled by the angle at which the loose material remains stable. As a result, many cinder cones have relatively similar steep profiles.
Size and lifespan
Most cinder cones are much smaller than shield volcanoes or stratovolcanoes. They may rise a few tens to several hundred meters above the surrounding landscape.
Some form during a single eruptive episode lasting weeks, months or years. Once the eruption ends, the original vent may never erupt again.
Eruption behavior
Cinder cones are often associated with Strombolian eruptions, in which gas bubbles burst near the surface and throw lava fragments into the air.
Lava may also escape from the base of the cone after accumulating within the crater. This can produce lava flows extending far beyond the cone itself.
Examples of cinder cones
- Parícutin in Mexico
- Sunset Crater in Arizona
- Cerro Negro in Nicaragua
- Capulin Volcano in New Mexico
- Puʻu ʻŌʻō on Kīlauea
Parícutin is especially famous because it emerged in a Mexican cornfield in 1943 and grew rapidly during a nine-year eruption.
Lava Domes
Lava domes are steep, rounded or irregular mounds formed when highly viscous lava accumulates near a volcanic vent.
Instead of flowing easily across the landscape, the lava moves slowly and piles up over the eruption site.
How lava domes grow
A lava dome may grow by the slow extrusion of thick lava from a vent. New material can push outward from inside the dome or spread across its surface in overlapping lobes.
Domes can form within summit craters, along volcano flanks or inside larger calderas.
Why lava domes are unstable
Lava domes often contain hot, fractured and gas-rich material. Their steep sides can become unstable as the dome grows.
If part of the dome collapses, the falling hot rock may break apart and generate pyroclastic flows. These dense, fast-moving currents can travel rapidly down valleys and across surrounding terrain.
Gas pressure can also build beneath a dome or vent blockage, producing powerful explosions.
Typical lava-dome hazards
- Dome collapse
- Pyroclastic flows
- Explosive decompression
- Block-and-ash flows
- Rockfalls
- Ash emissions
- Lahars caused by loose volcanic debris
Examples of lava domes
- Soufrière Hills on Montserrat
- Mount Unzen in Japan
- Mount Pelée in Martinique
- Chaitén in Chile
- Novarupta in Alaska
- The Lassen volcanic dome complex in California
Lava domes may grow and collapse repeatedly during long eruptive episodes, creating hazards that persist for months or years.
Fissure Eruptions
Fissure eruptions occur along elongated cracks rather than from a single central vent. These fractures may extend for hundreds of meters or many kilometers.
Lava can erupt simultaneously or sequentially from numerous points along the fissure, sometimes creating spectacular lines of lava fountains known as a curtain of fire.
How fissure eruptions form
Fissure eruptions commonly occur when magma rises through a dike—a sheet-like intrusion that forces the crust apart. If the dike reaches the surface, lava may erupt along the resulting fracture.
They are especially common in:
- Continental rift zones
- Mid-ocean ridges
- Volcanic hotspots
- The flanks of large shield volcanoes
- Regions undergoing crustal extension
Flood-basalt eruptions
Some enormous prehistoric fissure eruptions released vast volumes of basaltic lava across large regions. Repeated flows accumulated into thick volcanic provinces known as flood basalts or large igneous provinces.
Examples include the Deccan Traps in India, the Siberian Traps in Russia and the Columbia River Basalt Group in North America.
These events were far larger and longer-lasting than ordinary historical fissure eruptions. Their gas emissions and environmental effects may have contributed to major episodes of climate disruption and biological crisis.
Historic fissure eruptions
The 1783–1784 Laki eruption in Iceland released lava from a long fissure system and emitted enormous quantities of sulfur-rich gases. The eruption caused severe environmental and human impacts in Iceland and contributed to atmospheric effects across the Northern Hemisphere.
More recent fissure eruptions have occurred near Kīlauea in Hawaii and on Iceland’s Reykjanes Peninsula.
Fissure-eruption hazards
- Extensive lava flows
- Volcanic gas pollution
- Ground cracking
- Damage to roads and utilities
- Wildfires
- Evacuations across broad areas
Fissures may open outside the central summit area, making eruption location an important part of volcano monitoring and hazard planning.
Complex and Compound Volcanoes
Some volcanic systems cannot be classified as one simple cone or landform. They consist of overlapping vents, domes, cones, craters and collapse structures created during different phases of activity.
These are commonly described as complex volcanoes, compound volcanoes or volcanic complexes.
A volcanic complex may contain:
- Several stratovolcanoes
- Lava domes
- Cinder cones
- Explosion craters
- Calderas
- Fissure systems
- Hydrothermal areas
The center of activity may migrate as new magma pathways develop. One vent may become inactive while another begins erupting nearby.
Examples include the Three Sisters volcanic complex in Oregon, the Tongariro volcanic complex in New Zealand and several large volcanic systems in the Andes and Indonesia.
Calderas Explained
A caldera is a large volcanic depression formed mainly when the ground collapses after a substantial volume of magma is withdrawn from an underground reservoir.
Calderas are much larger than ordinary volcanic craters. They may span several kilometers or, in exceptional cases, tens of kilometers.
Caldera collapse can occur during or after a major explosive eruption, but not every caldera forms through a super-eruption. Some develop during repeated smaller eruptions, magma withdrawal or collapse within basaltic shield volcanoes.
Caldera systems may contain:
- Resurgent domes
- Crater lakes
- Lava domes
- Fumaroles and hot springs
- Numerous vents
- Earthquake swarms
- Areas of uplift and subsidence
Famous examples include Yellowstone, Toba, Campi Flegrei, Taupō, Santorini, Long Valley and Crater Lake.
The dedicated guide explores caldera formation, collapse mechanics, post-caldera activity, unrest and the difference between a crater and a caldera.
Supervolcanoes Explained
The term supervolcano is used for a volcanic system that has produced, or may be capable of producing, an eruption of exceptional size.
It does not describe a specific cone shape. Most systems associated with super-eruptions are broad calderas or volcanic fields rather than towering mountains.
A super-eruption is commonly associated with a Volcanic Explosivity Index of 8 and the eruption of at least roughly 1,000 cubic kilometers of material. Such eruptions are extremely rare.
Potential effects can include:
- Regional devastation from pyroclastic flows
- Widespread ashfall
- Major disruption to agriculture and infrastructure
- Aviation hazards
- Temporary climatic effects from sulfur aerosols
- Long-term transformation of the volcanic landscape
Well-known large caldera systems include Yellowstone, Toba, Taupō and the volcanic field associated with the ancient La Garita eruption.
The child pillar separates scientific evidence from exaggerated claims and explains magma reservoirs, super-eruption frequency, monitoring and realistic hazards.
Mud Volcanoes Explained
Mud volcanoes are cone-shaped or crater-like features that erupt mud, water, gases and sediment rather than molten rock.
They are not true magmatic volcanoes, but they are commonly grouped with unusual volcanic phenomena because of their eruptive behavior and volcano-like landforms.
Mud volcanoes form when pressurized fluids and gases rise through weak sedimentary layers. Methane, carbon dioxide and other gases can push water, clay and rock fragments toward the surface.
They occur in several geological settings, including:
- Petroleum-rich sedimentary basins
- Subduction zones
- Compressional mountain belts
- Fault zones
- Offshore continental margins
Most mud volcanoes are small, but some erupt violently, ignite escaping gas or release enormous volumes of mud that inundate surrounding areas.
Major mud-volcano regions occur in Azerbaijan, Indonesia, Pakistan, Trinidad, Romania, Italy and beneath parts of the ocean floor.
Submarine Volcanoes & Seamounts Explained
Most volcanic activity on Earth occurs beneath the ocean. Submarine volcanoes form along mid-ocean ridges, island arcs, hotspots and underwater rift zones.
Many remain permanently submerged, while others grow high enough to become volcanic islands.
What is a seamount?
A seamount is a large underwater mountain rising from the ocean floor but not reaching the sea surface. Many seamounts are extinct or dormant volcanoes, although some remain active.
Flat-topped seamounts known as guyots were once volcanic islands or shallow-water volcanoes that were eroded before sinking below sea level.
How underwater eruptions differ
Water pressure suppresses gas expansion at great depth, so many deep submarine eruptions produce lava flows rather than large atmospheric explosions.
In shallow water, however, interaction between magma and seawater can become highly explosive. Such eruptions may produce:
- Steam explosions
- Fine volcanic ash
- Pumice rafts
- Base surges
- Volcanic islands
- Submarine landslides
- Tsunamis
Hydrothermal vents associated with submarine volcanism release heated, mineral-rich fluids and support unusual ecosystems that do not depend directly on sunlight.
Examples of major submarine volcanic systems include Hunga Tonga–Hunga Haʻapai, Axial Seamount, Kick-’em-Jenny and the numerous volcanoes of the Mariana and Tonga–Kermadec arcs.
Comparison of the Main Volcano Types
| Volcano type | Typical shape | Common magma or material | Typical activity | Main hazards |
|---|---|---|---|---|
| Shield volcano | Broad with gentle slopes | Mostly basaltic lava | Lava flows, fountains and fissure activity | Lava, gases, earthquakes and ground cracking |
| Stratovolcano | Tall, steep and layered cone | Basaltic to rhyolitic magma | Effusive and explosive eruptions | Pyroclastic flows, ashfall, lahars and collapse |
| Cinder cone | Small, steep cone with summit crater | Scoria, bombs and lapilli | Short-lived Strombolian eruptions | Ballistic fragments, ash and lava flows |
| Lava dome | Steep mound or irregular plug | Viscous dacitic or rhyolitic lava | Slow extrusion and dome growth | Dome collapse, explosions and pyroclastic flows |
| Fissure system | Elongated cracks and lava fields | Commonly basaltic magma | Curtains of fire and extensive lava flows | Lava, gases and widespread ground disruption |
| Caldera | Large collapse depression | Variable magma composition | Collapse, explosive eruptions and later unrest | Ashfall, pyroclastic flows, gases and deformation |
| Mud volcano | Small cone, mound or crater | Mud, water, sediment and gas | Mud extrusion and gas release | Mudflows, gas emissions and occasional explosions |
| Submarine volcano | Underwater cone, ridge or seamount | Mostly basaltic, but variable | Submarine lava flows or explosive shallow eruptions | Tsunamis, pumice, ash, landslides and gas |
These are general patterns rather than rigid rules. Individual volcanoes may produce several eruption styles or evolve from one landform into a more complex volcanic system.
What Controls the Shape of a Volcano?
A volcano’s form reflects the interaction of magma, gases, eruption rate, topography and time.
The most important controls include:
Magma viscosity
Fluid lava can spread across large areas and build broad slopes. Viscous lava tends to remain close to the vent and may form steep domes or short, thick flows.
Eruption explosivity
Explosive eruptions fragment magma into ash, pumice, scoria and other tephra. The accumulation of this material can build steep cones or widespread deposits.
Eruption frequency
Repeated eruptions from one central vent may build a large cone, while migrating vents can create a volcanic field or complex.
Vent geometry
A central vent favors cone development, whereas long fractures produce fissure eruptions and broad lava fields.
Erosion and collapse
Landslides, crater collapse, caldera formation, glaciers and rivers can dramatically reshape an existing volcano.
Tectonic setting
Subduction zones, rifts, mid-ocean ridges and hotspots produce different magma compositions and volcanic structures.
Frequently Asked Questions About Volcano Types
What are the main types of volcanoes?
The main volcano types include shield volcanoes, stratovolcanoes, cinder cones, lava domes and fissure systems. Large volcanic structures also include calderas, submarine volcanoes and complex volcanic fields.
What is the most common type of volcano?
Cinder cones are among the most numerous volcano landforms on land, while submarine volcanoes along mid-ocean ridges account for a large share of Earth’s total volcanic activity.
What is the largest type of volcano?
Shield volcanoes can grow into the largest individual volcanic mountains by area and volume. Mauna Loa in Hawaii is one of the largest active volcanoes on Earth.
Which type of volcano is the most explosive?
Stratovolcanoes, lava-dome systems and large caldera systems can produce highly explosive eruptions because they may contain viscous, gas-rich magma. Eruption behavior varies, however, and no volcano type is explosive at all times.
What is the difference between a shield volcano and a stratovolcano?
A shield volcano is broad and gently sloping, usually built by fluid lava flows. A stratovolcano is steeper and composed of layers of lava and fragmented volcanic material, often with a greater potential for explosive eruptions.
What is the difference between a cinder cone and a stratovolcano?
A cinder cone is generally small and built mainly from loose volcanic fragments around one vent. A stratovolcano is much larger, longer-lived and built from repeated layers of lava, ash and other eruptive deposits.
Is a caldera a type of volcano?
A caldera is primarily a large volcanic collapse structure rather than a simple cone type. A caldera may contain numerous vents, domes, craters and later volcanoes within the depression.
Is every caldera a supervolcano?
No. Calderas form across a wide range of eruption sizes and volcanic settings. Only a small number are associated with eruptions large enough to be described as super-eruptions.
Are mud volcanoes real volcanoes?
Mud volcanoes resemble volcanoes and can erupt forcefully, but they do not normally involve molten rock. They release mud, sediment, water and gases from pressurized underground formations.
Can an underwater volcano become an island?
Yes. Repeated submarine eruptions can build a volcanic cone upward until it reaches the sea surface. The new island may survive, expand or be rapidly eroded by waves.
Can one volcano belong to more than one type?
Yes. A volcanic system may combine a stratovolcano, lava domes, cinder cones, fissures and a caldera. Volcanoes also evolve, collapse and develop new vents throughout their geological history.
