In a volcanic eruption, lava, volcanic bombs, ash, and various gases are expelled from a volcanic vent and fissure. While many eruptions only pose dangers to the immediately surrounding area, Earth's largest eruptions can have a major regional or even global impact, with some affecting the climate and contributing to mass extinctions.^[1][2] Volcanic eruptions can generally be characterized as either explosive eruptions, sudden ejections of rock and ash, or effusive eruptions, relatively gentle outpourings of lava.^[3] A separate list is given below for each type.

There have probably been many such eruptions during Earth's history beyond those shown in these lists. However erosion and plate tectonics have taken their toll, and many eruptions have not left enough evidence for geologists to establish their size. Even for the eruptions listed here, estimates of the volume erupted can be subject to considerable uncertainty.^[4]

Explosive eruptions

This list is incomplete; you can help by adding missing items. (September 2015)

In explosive eruptions, the eruption of magma is driven by the rapid release of pressure, often involving the explosion of gas previously dissolved within the material. The most famous and destructive historical eruptions are mainly of this type. An eruptive phase can consist of a single eruption, or a sequence of several eruptions spread over several days, weeks or months. Explosive eruptions usually involve thick, highly viscous, silicic or felsic magma, high in volatiles like water vapor and carbon dioxide. Pyroclastic materials are the primary product, typically in the form of tuff. Eruptions the size of that at Lake Toba 74,000 years ago, at least 2,800 cubic kilometres (670 cu mi), or the Yellowstone eruption 620,000 years ago, around 1,000 cubic kilometres (240 cu mi), occur worldwide every 50,000 to 100,000 years.^{[1][n 1]}

Effusive eruptions

This list is incomplete; you can help by adding missing items. (September 2015)

Effusive eruptions involve a relatively gentle, steady outpouring of lava rather than large explosions. They can continue for years or decades, producing extensive fluid mafic lava flows.^[43] For example, Kīlauea on Hawaiʻi continuously erupted from 1983 to 2018, producing 2.7 km³ (1 cu mi) of lava covering more than 100 km² (40 sq mi).^[44] Despite their ostensibly benign appearance, effusive eruptions can be as dangerous as explosive ones: one of the largest effusive eruptions in history occurred in Iceland during the 1783–1784 eruption of Laki, which produced about 15 km³ (4 cu mi) of lava and killed one fifth of Iceland's population.^[43] The ensuing disruptions to the climate may also have killed millions elsewhere.^[45] Still larger were the Icelandic eruptions of Katla (the Eldgjá eruption) circa 934, with 18 km³ (4 cu mi) of erupted lava, and the Þjórsárhraun eruption of Bárðarbunga circa 6700 BC, with 25 km³ (6 cu mi) lava erupted, the latter being the largest effusive eruption in the last 10,000 years.^[46] The lava fields of these eruptions measure 565 km² (Laki), 700 km² (Eldgjá) and 950 km² (Þjórsárhraun).