Surtsey is a volcanic island that formed in a submarine eruption. This means that the volcano erupted underwater, and the lava interacted with the seawater.

Here's a breakdown of the types of eruptions Surtsey has experienced:

* Hydrovolcanic eruptions: These eruptions are characterized by explosive interactions between magma and water. The rapid heating of water creates steam and causes violent explosions. Surtsey's initial eruption was strongly hydrovolcanic, resulting in large amounts of ash and steam.

* Strombolian eruptions: These are relatively mild eruptions with fountains of lava and tephra (rock fragments) ejected from the vent. Surtsey has experienced Strombolian eruptions throughout its history.

* Effusive eruptions: These eruptions involve the slow and steady flow of lava from the vent, building up the island's landmass. Surtsey has also experienced effusive eruptions, primarily after its initial formation.

It's important to note: Surtsey's eruptions have been relatively infrequent since its formation in 1963. While there have been minor eruptive events, the island is currently considered dormant.