What is a Strombolian eruption?

A Strombolian eruption is a relatively mild type of volcanic eruption characterized by sporadic blasts and the ejection of incandescent scoria, lapilli, and volcanic bombs. Named after the Italian volcano Stromboli, these eruptions typically feature a Volcanic Explosivity Index of 1 or 2 and can last for decades or even centuries. The explosive activity is driven by gas bubbles, or slugs, rising through the magma column and bursting near the surface, forming part of the broader category of magmatic eruptions.

What we know

• Strombolian eruptions are categorized under magmatic eruptions, which involve the decompression of gas within magma to propel it forward. [1, 3]
• Strombolian eruptions are characterized by relatively mild blasts typically having a Volcanic Explosivity Index of 1 or 2, ranking above Hawaiian and submarine eruptions but below Vulcanian and Surtseyan types. [2, 3]
• The eruptions consist of ejecting incandescent scoria, lapilli, and volcanic bombs to altitudes ranging from tens to a few hundreds of metres. [2]
• Gas coalesces into large bubbles called gas slugs that rise through the magma column and burst near the top due to decreasing pressure. [2]
• Strombolian eruptive activity can be very long-lasting because the conduit system is not strongly affected by the explosions, allowing the system to reset repeatedly. [2]

Still open

• Gas slugs can form as deep as 3 kilometers underground, making them difficult to predict.

Where to go next

• the bigger pictureWhat is the Volcanic Explosivity Index?
• a case in pointHow does Parícutin volcano demonstrate Strombolian activity?
• how it workedHow do gas slugs form deep inside magma columns?
• compared withHow does a Vulcanian eruption differ from a Strombolian one?
• how we knowWhy did the Romans call Stromboli the Lighthouse of the Mediterranean?
• an unexpected connectionHow can a volcano erupt continuously for nearly a decade like Parícutin?Monogenetic cones like Parícutin can erupt in the Strombolian style continuously for many years because their conduit systems remain stable and repeatedly reset.

Sources

• [1]Strombolian eruption (Wikidata Q611880) · CC0 1.0
• [2]Strombolian eruption · CC BY-SA 4.0
• [3]Volcanic eruption · CC BY-SA 4.0
• [4]2021 Cumbre Vieja volcanic eruption · CC BY-SA 4.0
• [5]Vulcanian eruption · CC BY-SA 4.0