Supervolcanoes 101 | National Geographic

Summary

Supervolcanoes, Earth's most powerful and complex volcanic phenomena, are marked by calderas and can undergo explosive eruptions, reaching magnitude eight on the Volcanic Explosivity Index. They experience a life cycle of pressure build-up, supereruption, and resurgence, with the latter stage often leading to the creation of natural beauty and life renewal. The Campi Flegrei in Italy and the Taupo in New Zealand exemplify this cycle, with the latter's last eruption expelling enough material for half a million Great Pyramids of Giza.

Takeaways

• 🌋 Supervolcanoes are the most powerful and complex type of volcano, capable of the most violent eruptions.
• 🌍 There are around 20 supervolcanoes worldwide, often characterized by large depressions called calderas.
• 🔥 They erupt at a magnitude of eight on the Volcanic Explosivity Index, which is the highest and most violent classification.
• 🔥🔧 The life cycle of a supervolcano includes three major stages: magma accumulation, supereruption, and resurgence.
• 🌡️ The first stage involves a hotspot, a pocket of trapped magma under the Earth's crust, which builds pressure and can cause the ground to rise.
• 📈 The Campi Flegrei in Italy has demonstrated significant ground uplift due to magma accumulation in recent decades.
• 💥 A supereruption occurs when the pressure in the magma reservoir reaches a critical point, ejecting vast amounts of tephra into the atmosphere.
• 🌋💨 The most recent supereruption was at Taupo in New Zealand, which ejected about 1,100 cubic kilometers of tephra.
• 🕰️ After a supereruption, a supervolcano enters the resurgence stage, where the magma reservoir collapses, forming a caldera.
• 🏞️ The Yellowstone Caldera is an example of a supervolcano in the resurgence stage, with a lake and geothermal features formed post-eruption.
• 🌿 Supervolcanoes, despite their destructive power, can lead to the creation of new ecosystems and natural beauty after their eruptions.

Q & A

What are supervolcanoes?

Supervolcanoes are the most violent and complex class of volcanoes, characterized by large depressions in the ground called calderas, located above multiple openings in the Earth's crust.

How many supervolcanoes are there on Earth?

There are around 20 supervolcanoes scattered across the planet.

What is the Volcanic Explosivity Index and how does it classify supervolcano eruptions?

The Volcanic Explosivity Index is a scale that measures the explosivity of volcanic eruptions. Supervolcanoes are classified at a magnitude of eight, which is the highest and most violent classification on the index.

What are the three major stages in the life cycle of a supervolcano?

The three major stages in the life cycle of a supervolcano are the surge of trapped magma, a supereruption, and a resurgence.

What is a hotspot in the context of supervolcanoes?

A hotspot is a pocket of magma trapped under the Earth's crust that is fed by a pipeline deep into Earth's molten interior. It grows and builds pressure underground.

How does the ground react when a hotspot forms under it?

When a hotspot forms under the ground, it causes the crust above to be pushed upward due to the buildup of pressure from the trapped magma.

What is the Campi Flegrei supervolcano and what has it done in recent times?

The Campi Flegrei is a supervolcano on the west coast of Italy that has pushed the ground up several times over the past few decades, with one instance causing the ground to swell up to six and a half feet within two years.

What happens during a supereruption?

During a supereruption, the buildup of pressure in a magma reservoir reaches a critical mass and explodes, sending over 1,000 cubic kilometers of tephra, or ash and rocky material, into the sky.

When was the most recent supereruption and which supervolcano was responsible?

The most recent supereruption occurred approximately 26,000 years ago at the supervolcano Taupo in New Zealand.

What is the Taupo supervolcano's supereruption estimated to have ejected?

The Taupo supervolcano ejected about 1,100 cubic kilometers of tephra into the air during its supereruption, which is enough material to constitute nearly half a million Great Pyramids of Giza.

What is the resurgence stage of a supervolcano and what happens during this stage?

The resurgence stage is when a supervolcano's magma reservoir collapses after a supereruption, forming a caldera. Freshwater collects in the caldera to form a lake, plants and wildlife return, and geothermal features emerge.

What is the Yellowstone Caldera and what stage is it currently in?

The Yellowstone Caldera is a supervolcano in the United States that is currently in the resurgence stage after a supereruption occurred about 640,000 years ago.

How do supervolcanoes contribute to natural beauty after their cataclysmic events?

Supervolcanoes create unparalleled natural beauty by forming unique geological features, lakes, and supporting the return of plant and wildlife life after their destructive eruptions.