The Types of Volcanic Eruptions; A Volcanologist's Guide

Summary

This video explores the 14 types of volcanic eruptions, explaining their characteristics and the types of volcanoes that typically produce them. From submarine eruptions, marked by gentle lava flows and steam, to explosive events like Plinian and Pelean eruptions, the video covers a range of volcanic phenomena. It also highlights more specific eruptions, such as Icelandic, Hawaiian, Strombolian, and Vulcanian, as well as the lesser-known phreatic and phreatomagmatic eruptions. The video aims to help viewers understand the diverse volcanic hazards and how to recognize different types of eruptions.

Takeaways

• 😀 There are typically 40 to 55 volcanoes actively erupting on Earth at any given time.
• 😀 The type of eruption is crucial for understanding the hazards posed by the volcano.
• 😀 Submarine eruptions occur deep underwater and are characterized by gentle lava flow and steam columns.
• 😀 Sub-glacial eruptions happen beneath ice sheets and often cause large floods known as jokulhaups.
• 😀 Surtseyan eruptions are explosive, occurring at shallow depths underwater, producing black ash-rich explosions.
• 😀 Icelandic eruptions are peaceful, involving long fissures where lava gently spills from the ground.
• 😀 Hawaiian eruptions involve lava fountains, typically occurring at shield volcanoes or flank vents.
• 😀 Strombolian eruptions are marked by bursts of volcanic gas and small explosions, forming cinder cones.
• 😀 Vulcanian eruptions are explosive events at stratovolcanoes, often resulting in pyroclastic flows and ash clouds.
• 😀 Phreatic eruptions involve the explosion of steam due to groundwater heating by underlying magma, with no lava ejected.
• 😀 Plinian eruptions are highly explosive, with sustained ash plumes that reach the stratosphere, sometimes causing pyroclastic flows.
• 😀 An ultraplinian eruption is an extremely violent eruption that ejects more than 10 cubic kilometers of material.
• 😀 Pelean eruptions are powerful lateral explosions, creating pyroclastic flows that travel farther than most other eruptions.

Q & A

What is the most common type of volcanic eruption and where does it occur?

The most common type of volcanic eruption is the submarine eruption, which occurs beneath the ocean's surface. These eruptions are characterized by gentle lava effusion and the release of steam, ash, and volcanic gases.

What makes subglacial eruptions different from other types of eruptions?

Subglacial eruptions occur beneath thick ice sheets, and often the eruption column doesn't break the surface of the ice. These eruptions are also known for triggering massive floods of glacial water, called jökulhlaups.

What is a surtseyan eruption, and under what conditions does it occur?

A surtseyan eruption happens when a submarine eruption occurs at depths of less than 50 meters. The magma explosively interacts with the surrounding water, creating short, black ash-rich explosions and a central white plume.

How do Icelandic eruptions differ from other eruption types?

Icelandic eruptions are characterized by long fissures or cracks in the ground through which magma gently erupts, forming rivers of molten rock. These eruptions typically involve low-silica basaltic magma and occur at divergent plate boundaries or rift zones.

What defines a Hawaiian eruption?

A Hawaiian eruption is characterized by lava fountains that emit lava and occasional small fragments of ash from the summit or flanks of a shield volcano. These eruptions are generally non-explosive and involve basaltic magma.

What happens during a strombolian eruption?

In a strombolian eruption, bursts of volcanic gas and small explosions propel lava fragments high into the air, often up to several hundred meters. This eruption type is loud and typically results in the formation of cinder cones.

What is a vulcanian eruption and how does it occur?

A vulcanian eruption occurs when pressure builds up beneath a stratovolcano, causing an explosive release of ash and gas. These eruptions are characterized by thick ash clouds and often produce pyroclastic flows. They can also occur when the side of a lava dome becomes unstable.

What is a phreatic eruption, and does it involve lava?

A phreatic eruption occurs when magma heats surrounding groundwater, causing it to flash to steam and create an explosive release of pressure. This type of eruption does not involve lava; instead, it results in the expulsion of steam, water, and sometimes small fragments of rock.

How does a plinian eruption differ from a sub-plinian eruption?

A plinian eruption involves a sustained eruption column that reaches high altitudes, often extending into the stratosphere. If the eruption column is less than 20 kilometers high, it is considered a sub-plinian eruption. The key difference is the height and scale of the eruption.

What defines an ultraplinian eruption, and how rare is it?

An ultraplinian eruption is an extremely powerful eruption that ejects more than 10 cubic kilometers of material. These eruptions are very rare but highly explosive, producing massive amounts of ash and pyroclastic material.