No ashfall deposits have been found, and the erupted volume could be 2-3 times larger than listed if any ashfall deposits are found.
Paraná Province suggests an effusive origin from local sources. Even for the eruptions listed here, estimates of the volume erupted can be subject to considerable uncertainty. However erosion and plate tectonics have taken their toll, and many eruptions have not left enough evidence for geologists to establish their size. There have probably been many such eruptions during Earth's history beyond those shown in these lists. A separate list is given below for each type. Volcanic eruptions can generally be characterized as either explosive eruptions, sudden ejections of rock and ash, or effusive eruptions, relatively gentle outpourings of lava. 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. In a volcanic eruption, lava, volcanic bombs and ash, and various gases are expelled from a volcanic vent and fissure. The 1991 eruption of Mount Pinatubo, the largest eruption since 1912, is dwarfed by the eruptions in this list.
