Types of Volcanoes Based on Structure

mountain

land formation without vent

volcano

land formation with vent

primary part

→ Magma chamber
→ Conduit/vent
→ Crater
→ Base
→ Blank

secondary part

→ Sills
→ Dikes
→ Parasic cone
→ Caldera

magma chamber

Magma accumulates underground in an open space or an area of a highly fractured substrate

central vent

Conduits may take the form of this which is shaped like a vertical pipe

flank vent

smaller conduits issuing from a central vent

fissure

elongated crack

dikes

rock sheets that can form from magma when they seep into cracks in rocks.

sills

beds of rocks that form as a result of rock formation between layers of older materials

crater

The end of a pipe-like conduit at the top of the mound

summit eruptions

eruptions issuing from the crater

parasitic cones

Eruptions issuing from flank vents can produce these around a mound.

caldera

a large circular depression with steep walls and is at least 1km wide.

Taal Lake is an example of a collapsed caldera

lava dome

mounds are roughly circular. These domes form when viscous lava cannot flow too far due to the viscosity and cools into a mound.

shield volcanoes

broad gently-sloping mounds shaped like a soldier’s shield.

composite volcanoes

also known as stratovolcanoes, are tall, steep, conical mountains.

pyroclastic cones

are small, steep mounds composed of tephra or volcanic fragments formed by explosive eruptions.

volcanoes according to activity

→ Active
→ Inactive
→ Potentially active/dormat

Mt. Kilauea

located in Hawaii and is the most active volcano in the world

active volcano

→ have eruptive histories; there has been a recorded eruption in historical times.
→ Alternatively, dateable erupted materials confirm that they erupted within the last 10,000 years.
→ There are currently 23 active volcanoes being monitored by PHIVOLCS. (Philippine institute of volcanology and seismology)

mayon volcano

→ The famous “perfect cone” signifies Mayon’s structure as a stratovolcano, dominating the plains of Albay
→ Last eruption was in 2018/2023
→ More than 52 historical eruption

taal volcano

→ A geologically complex region, Taal Lake represents a collapsed caldera covering 267 km2
→ Volcano Island is the main activity region, surrounded by several parasitic pyroclastic cones.
→ Last eruption 1977/ December 3 2024 and more than 33 historical eruptions

mt. kanlaon

→last eruption was in 2016/ June 3, 2024/ December 9, 2024,
→ More than 30 eruptions;
→ The highest mountain in the Visayas is a complex stratovolcano with several flank vents around the spectacular summit crater

mt. bulusan

→ Last eruption was in 2017/ June 12, 2022, 18 eruptions;
→ Mayon’s often overlooked neighbor, Bulusan is part of the Irosin Caldera, a complex volcanic field spanning most of Sorsogon.

inactive volcanoes

→have no eruptive histories, are heavily weathered, and will never erupt again.
→ PHIVOLCS lists 281 inactive volcanoes, with several being unnamed peaks.

mount arayat

→ This volcano is located in Pampanga, on the island of Luzon. Mount Arayat’s hiking trails are well-known, and there is a rich history of folklore and superstition surrounding the mountain.

seven lakes of laguna

→ Also known as the Seven Lakes of San Pablo.

→ These lakes are the following: Lake Bunot, Lake Palakpakin, Lake Muhikap, Lake Sampaloc, Lake Yambo, Lake Pandin, and Lake Calibato.

All of these are inactive crater lakes found in San Pablo, Laguna.

potentially active volcanoes

similar with dormant volcanoes, have no eruptive histories and no recent dateable materials, but are morphologically recent and in some instances present signs of activity or remnant heat.
→ PHIVOLCS lists 26 potentially active volcanoes.

mount apo

→ the country’s highest peak, which still showcases sulfuric steam and in fact hosts a geothermal plant.
→ is a stratovolcano and is considered a national park.

cuernos de negros

→ also known as Mount Talinis. Dominating southeast Negros Island, this range exhibits areas of geothermal alteration and steaming, and will soon host a geothermal plant.
→ Mount Talinis is a popular tourist spot due to the Balinsasayao Twin Lakes National Park.

mount isarog

located in Camarines Sur. It is a stratovolcano famous for its rich and unique biodiversity.

magmatic eruptions

thermal expansion of the dissolved gases in lava. As magma rises, the lithostatic pressure is reduced, allowing gases to expand.
→ viscosity of the melt and other factors such as blockages in the conduit determine the explosivity of the eruption

plinian

result from the extreme buildup of gases in the magma chamber and conduit

Peléan

very similar to Vulcanian eruptions, except that they are of greater magnitude. These eruptions are characterized by nuée ardente or “glowing avalanches,” which result from the collapse of the eruption column into an incandescent pyroclastic flow.

vulcanian

result from more viscous lava, which slows down bubble formation and clogs up conduits. The pressure then builds up until the volcano explodes, releasing large volumes of pyroclastic debris

icelandic

sustained fissure eruptions, producing curtains of basaltic lava. Prolonged eruptions produce Large Igneous Provinces (LIPs).

strombolian

result of the bursting of clumps of gas bubbles at the surface

hawaiian

produce low-viscosity basaltic lava flows and fountains. It evolves from Icelandic eruptions. Over time, Hawaiian eruptions produce shield volcanoes.

surtseyan

occurs in a shallow body of water, and are usually characterized by strong explosions as a result of magma coming in contact with water.

phreatomagmatic

→ These eruptions are driven by the violent thermal contraction of magma when it interacts with water, resulting in an explosion.
→ The best example is a Surtseyan eruption, caused by shallow-water lava interaction at sea or with an aquifer. It is the equivalent of a “wet” Strombolian eruption.

phreatic

→ These are purely steam-driven, caused by the expansion of water into steam when heated by a nearby magma chamber or volcanic source.
→ The water flash boils and explodes, fracturing surrounding rock and even tearing off debris.