Volcanoes are diverse! They range from the majestic Mount Rainier, to colossal shield volcanoes like Mauna Loa (Hawai’i Volcanoes National Park), and to volcanic fields that can cover hundreds of square miles such as at Craters of the Moon National Monument.
Some volcanoes are picturesque, others less so. They vary in size from small cinder cones that stand only a few hundred feet tall to the most massive mountains on Earth. Some have textbook-perfect conical shapes, and others are more irregular in form.
Some volcanoes erupt only once in eruptions that last for intervals as short as a few days or less, while others may have periods of activity that span expanses of time as great as a few million years.
Each type of volcano has a characteristic size and form, eruption type(s) and style, eruption period/longevity, rock type(s), and sets of volcanic features. There is an interplay between compositions of magma that are erupted and the physical features of a volcano.
Magma chemistry determines its physical characteristics, which in turn, control eruption dynamics and how easily lava can flow. Gas content and the rate of eruption also impact explosivity.
Some types of volcanoes tend to erupt only once (and are called monogenetic), and others erupt multiple times over their lifespan (and are called polygenetic).
Each volcano is somewhat unique, but most volcanoes can be classified into one of several types. The most well-known types of volcanoes are cinder cones, composite volcanoes (stratovolcanoes), shield volcanoes, and Lava domes.
Types of Volcanoes
Viscosity is important in volcanology. An eruption of highly viscous (very sticky) magma tends to produce steep-sided volcanoes with slopes that are about 30–35°. That’s because the viscous volcanic material doesn’t flow that far from where it is erupted, so it builds up in layers forming a cone-shaped volcano known as a stratovolcano.
Shield volcanoes, on the other hand, have gentle slopes that are less than 10° and erupt more fluid lavas called basalt. When a shield volcano erupts, the basalt can flow great distances away from the vent to produce broad, gentle slopes.
#1. Cinder Cone Volcano.
Cinder cones are the most common type of volcano in the world. They may look like an idealized depiction of a volcano as they are steep, conical hills that usually have a prominent crater at the top.
Cinder cones are more technically known as scoria cones. Scoria are irregularly shaped, highly vesicular (bubble-shaped cavities) fragments of lava that erupt into the air and are typically solid when they land.
Cinder is a more colloquial term that is widely used in the United States for pieces of scoria that are roughly nut- to fist-size. Cinder cones are often surrounded by dark lava flows erupting from near their base.
Magma Composition
Most cinder cones are basaltic to basaltic andesite in composition, but they may be andesitic (intermediate).
Examples
- Wizard Island in Crater Lake National Park is a cinder cone that formed after the caldera-forming eruption.
- Craters of the Moon National Monument contains 25 cinder cones.
- Cinder Cone in Lassen Volcanic National Park erupted about 1650 CE.
#2. Composite Volcano (stratovolcanoes).
Composite volcanoes can be the most picturesque of all volcanoes. A classic composite volcano is conical with a concave shape that is steeper near the top. These mountains commonly have snow-covered peaks standing high above the surrounding mountainous terrain.
Composite cones are large volcanoes (many thousands of feet or meters tall) generally composed of lava flows, pyroclastic deposits, and mudflow (lahar) deposits, as well as lava domes. Composite volcanoes are active over long periods (tens to hundreds of thousands of years), and erupt periodically.
Composite volcanoes are also called stratovolcanoes. Some geologists avoid the use of the term “stratovolcano” because these volcanoes typically are not stratified and do not consist of orderly layers of lava flows and pyroclastic deposits.
Magma Composition
Composite volcanoes usually erupt a range of compositions from basalt to rhyolite, but intermediate (andesitic) and dacitic magmas are most common.
Mount Rainier has less compositional diversity than many composite cones as it consists of mostly andesitic lava flows and lahar deposits.
Example:
- Redoubt Volcano and Iliamna Volcano are active composite volcanoes in Lake Clark National Park.
- Katmai National Park contains several composite volcanoes, eight of which are active. The most recent eruptions in Katmai were from Trident Volcano between 1953 and 1974.
- Vent Mountain and Half Cone are composite volcanoes that formed within Aniakchak Caldera in Aniakchak National Monument following the caldera-forming eruption that occurred 3,700 years ago.
#3. Shield Volcano.
Although shield volcanoes are the largest volcanoes on Earth, they do not form soaring mountains with conical peaks like composite volcanoes. Instead, they are broad volcanoes with gentle slopes and are shaped somewhat like a warrior’s shield lying flat on the Earth. Shield volcanoes have a convex shape as they are flatter near the summit.
Shield volcanoes are truly massive with volumes that dwarf other types of volcanoes, even large composite volcanoes.
Shield volcanoes are usually constructed almost entirely of basaltic and andesitic lava flows which were very fluid when erupted. They are built by repeated eruptions intermittently over vast periods (up to a million years or longer).
Magma Composition
Shield volcanoes are usually basalt but can be constructed of mostly andesitic lava flows. Mauna Loa and Kīlauea erupt almost exclusively in basaltic lavas—shield volcanoes in Wrangell-St. Elias National Park is made up of andesitic lava flows.
Examples:
- Lava Beds National Monument (California) is on the northern flank of Medicine Lake Volcano, a large shield volcano.
- The Espenberg volcanic field in Bering Land Bridge National Monument (Alaska) contains five small shield volcanoes that formed during the Pleistocene.
- Wrangell-St. Elias National Park in Alaska contains eight andesitic shield volcanoes, including Mount Wrangell which is the youngest. Mount Wrangell is considered active since it is reported to have experienced a short explosive eruption in 1930.
- Kaloko-Honokōhau National Historic Park is located on the flank of Hualālai, one of the five shield volcanoes that make up the island of Hawai‘i.
#4. Lava Dome.
Lava domes or Volcanic domes are rounded, steep-sided mounds built by very viscous magma, usually either dacite or rhyolite. Such magmas are typically too viscous (resistant to flow) to move far from the vent before cooling and crystallizing. Domes may consist of one or more individual lava flows. Volcanic domes are also referred to as lava domes.
Lava Domes form from the slow extrusion of highly viscous silicic lava. These lavas are too thick to spread out into a lava flow. Most domes are small and many do not have a crater.
Some dome-forming eruptions start with highly explosive eruptions that wane into dome-building ones as the gas content in the magma decreases. Other dome-building eruptions begin effusively until the growing dome explodes or collapses to produce pyroclastic flows.
Volcanic domes can form volcanic edifices in their own right such as Lassen Peak in Lassen Volcanic National Park. Domes also occur in clusters. Domes are also frequently extruded in the summit craters of composite volcanoes such as at Redoubt Volcanoes in Lake Clark National Park. Domes may also grow within calderas as part of a post-caldera eruptive phase.
Magma Composition
Domes are usually made up of silicic lavas (dacite, rhyodacite, or rhyolite) since high viscosity is necessary to form domes.
Example:
- Lassen Volcanic National Park contains multiple lava domes. Lassen Peak is the world’s largest dome with a peak elevation of 10,457 feet (3,187 m).
- Novarupta Dome in Katmai National Park was placed at the end of the Valley of Ten Thousand Smokes eruption in 1912.
- In Valles Caldera National Preserve, at least seven lava dome complexes formed along the ring fracture of the Valles Caldera during post-caldera volcanic activity.
Types of Volcanoes Based on Eruption Frequency
#1. Active Volcanoes.
Active volcanoes erupt regularly examples of active volcanoes are Kīlauea in Hawaii, Mount Etna in Italy, and Mount Stromboli also in Italy which has been erupting almost constantly for the last 2000 years.
Example: Mauna Loa
Rising gradually to more than 4 km (2.5 mi) above sea level, Hawaii’s Mauna Loa is the largest active volcano on our planet. Its submarine flanks descend to the sea floor an additional 5 km (3 mi), and the sea floor, in turn, is depressed by Mauna Loa’s great mass another 8 km (5 mi).
#2. Dormant Volcanoes.
Dormant volcanoes are volcanoes that have not erupted in a long time but are expected to erupt again in the future. Examples of dormant volcanoes are Mount Kilimanjaro, in Tanzania, Africa, and Mount Fuji in Japan.
Example: Haleakala
The largest dormant volcano in the world, Haleakala, makes up a large part of Maui. Mount Haleakala is also called the East Maui Volcano. Haleakala is considered a dormant volcano because it has not erupted in a long time, but it could erupt again in the future. Haleakala is a huge shield volcano.
#3. Extinct Volcanoes.
Extinct volcanoes are those which have not erupted in human history. Examples of extinct volcanoes are Mount Thielsen in Oregon in the US and Mount Slemish in Co. Antrim.
Example: Tamu Massif
Tamu Massif is an extinct volcano in the Pacific Ocean, around 1,000 miles east of Japan. It covers an area of 120,000 square miles—roughly the size of New Mexico. It is part of the Shatsky Rise underwater mountain range, which formed about 145 million years ago during a series of volcanic eruptions.