Caldera facts for kids

For other uses, see Caldera (disambiguation).

A caldera is a huge, bowl-shaped hollow in the ground. It forms after a powerful volcanic eruption empties the magma chamber below. When the magma is gone, the ground above can no longer support itself. It then collapses inwards, creating a large depression. These depressions can be many kilometers wide. Even though they look like giant craters, calderas are actually a type of sinkhole. They form when the ground sinks, not from an explosion. Forming a caldera is a rare event. Only a few have happened in the last 100 years. Recent examples include Kīlauea in Hawaii in 2018 and Hunga Tonga–Hunga Haʻapai in 2022.

Mount Mazama's eruption timeline, an example of caldera formation

Understanding Calderas: Giant Volcanic Bowls

What Does "Caldera" Mean?

The word caldera comes from the Spanish word for "cooking pot." This is because many calderas look like huge cooking pots or bowls. A German geologist named Leopold von Buch first used the term in geology. He saw these amazing landforms in the Canary Islands in 1815.

How Calderas Form: A Volcanic Collapse

Calderas form when a magma chamber under a volcano empties out. This can happen during a huge, explosive volcanic eruption. It can also occur during slower, flowing eruptions. When a lot of magma leaves the chamber, the ground above loses its support. A circular crack, called a "ring fault," forms around the edge of the magma chamber. This crack can even become a path for more magma to rise. As the chamber empties, the central part of the volcano starts to sink. This sinking can happen all at once in a giant event. Or, it can happen slowly over several eruptions. The collapsed area can be hundreds of square kilometers wide.

Animation of an analogue experiment showing the origin of a mock volcanic caldera in box filled with flour

Types of Calderas: Explosive vs. Gentle

Not all calderas form in the same way. Scientists group them into different types based on how they erupt.

Explosive Calderas: Powerful Eruptions

Some calderas form from incredibly powerful, explosive eruptions. These happen when the magma is thick and sticky, like peanut butter. This type of magma also holds a lot of gas. When it rises to the surface, the gas escapes quickly, causing a huge explosion. This explosion sends a mix of hot gas and volcanic ash high into the sky. Sometimes, this column of ash collapses. It then rushes down the volcano's sides as fast-moving pyroclastic flows. These flows can cover huge areas. For example, the Yellowstone Caldera erupted about 650,000 years ago. It released enough material to cover a large part of North America in ash. After the eruption, the center of the caldera might even rise again. This forms a "resurgent dome" inside the caldera. These massive eruptions can change the environment around the world. They can cause a "volcanic winter," making temperatures drop globally.

Famous Explosive Calderas: Toba and Valles

The Valles Caldera in New Mexico is a great example of an explosive caldera. It formed about 1.25 million years ago. Scientists have studied it a lot to understand how these features form. The Lake Toba caldera in Indonesia formed about 74,000 years ago. Its eruption was the largest known explosive event in the last 25 million years. It released a massive amount of material. This eruption caused a significant drop in global temperatures.

Valle Caldera, New Mexico

Landsat image of Lake Toba, on the island of Sumatra, Indonesia (100 km/62 mi long and 30 km/19 mi wide, one of the world's largest calderas). A resurgent dome formed the island of Samosir.

Topographic map of Cagar Alam Rawa Danau Caldera in Indonesia

Non-Explosive Calderas: Slow Subsidence

Not all calderas form with huge explosions. Some, like those on Kīlauea and Mauna Loa in Hawaii, form differently. These volcanoes have runny, thin magma, like warm syrup. This magma flows out in large lava streams. When the magma chamber empties this way, the ground above slowly sinks. These are called subsidence calderas. They form more gradually than explosive calderas. For example, the caldera on Fernandina Island in the Galápagos Islands collapsed in 1968. Parts of its floor dropped 350 meters.

Satellite photograph of the summit caldera on Fernandina Island in the Galápagos archipelago

Oblique aerial photo of Nemrut Caldera, Van Lake, Eastern Turkey

Sollipulli Caldera, located in central Chile near the border with Argentina, filled with ice. The volcano is in the southern Andes Mountains within Chile's Parque Nacional Villarica.

Calderas Beyond Earth: Volcanoes in Space

Volcanoes and calderas are not just found on Earth! Scientists have discovered them on other planets and moons in our Solar System. These include Venus, Mars, the Moon, and Io, one of Jupiter's moons.

Lunar Calderas: Craters on the Moon

The Moon has many craters, mostly from meteorite impacts. But some caldera-like structures exist. The Compton-Belkovich Volcanic Complex on the far side of the Moon is thought to be a caldera.

Martian Calderas: Giant Volcanoes on Mars

Mars has huge shield volcanoes, similar to those on Earth. They all have one or more collapse calderas at their summits. Olympus Mons is the tallest volcano in the Solar System. It is more than three times the height of Mount Everest. Its summit has six nested calderas.

Venusian Calderas: Hot World, Huge Volcanoes

Venus has enormous lava flows covering most of its surface. Many of its mountains are large shield volcanoes. More than 80 of these volcanoes have summit calderas. These calderas average about 60 kilometers across.

Io's Calderas: Jupiter's Volcanic Moon

Io is a moon of Jupiter that is constantly volcanically active. This is due to the strong pull of Jupiter's gravity. Spacecraft like Voyager 1 and Voyager 2 have seen many erupting volcanoes on Io. Io has many calderas, some tens of kilometers wide.

Where to Find Calderas: Earth's Volcanic Wonders

Calderas are found all over the world. Here are a few examples from different continents:

Africa

Ngorongoro Crater (Tanzania)
Mount Fogo (Cape Verde)
Erta Ale (Ethiopia)

Antarctica

Deception Island

Asia

Mount Tambora (Sumbawa, Indonesia)
Krakatoa (Sunda Strait, Indonesia)
Lake Toba (Sumatra, Indonesia)
Mount Aso (Kumamoto Prefecture, Japan)
Mount Halla (Jeju-do, South Korea)
Mount Pinatubo (Luzon, Philippines)

Europe

Santorini (Greece)
Laacher See (Germany)
Phlegraean Fields (Italy)
Askja (Iceland)
Glen Coe (Scotland, UK)

Images for kids

3D computer image of Santorini, Greece
Aerial view of the Laacher See, Germany
View of the Phlegraean Fields near Naples, Italy
Caldeira do Faial on the Caldeira Volcano, Faial Island, Azores
Coatepeque Caldera, El Salvador crater lake
Crater Lake, Oregon, formed around 5,680 BC
Aniakchak-caldera, Alaska
NASA false-colour topographical relief image of Nabro (top) and Mallahle volcanic calderas (centre left)
Satellite image of Deception Island by Sentinel-2 (March 2023)
Caldera of Mount Tambora
Mount Pinatubo, Philippines
Caldera of the island Yankicha/Ushishir, Kuril Islands
Mokuʻāweoweo, Mauna Loa's summit caldera, covered in snow
Satellite photo of Lake Taupō
Aerial photograph of Sollipulli caldera, looking east