Types of volcanic eruptions eruptions are associated with volatile-rich dacitic to rhyolitic lavas, and occur most typically at stratovolcanoes. Eruptions can last anywhere from hours to days, with longer eruptions being associated with more felsic volcanoes. Although they are associated with felsic magma, Plinian eruptions can just as well occur at basaltic volcanoes, given that the magma chamber differentiates and has a structure rich in silicon dioxide. Plinian eruptions are similar to both Vulcanian and Strombolian eruptions, except that rather than creating discrete explosive events, Plinian eruptions form sustained eruptive columns. They are also similar to Hawaiian lava fountains in that both eruptive types
Felsic although sometimes used as a synonym, refers to a high-silica-content (greater than 63% SiO by weight) volcanic rock, such as rhyolite. The term was used more broadly in older geologic literature. It is considered archaic now, as the terms "acidic" and "basic rock" were based on an incorrect idea, dating from the 19th century, that "silicic acid" was the chief form of silicon occurring in rocks. The term "felsic" combines the words "feldspar" and "silica". The similarity of the term "felsic" to the German words "Fels", meaning "rock", and "felsig", meaning "rocky", is purely accidental, as "feldspar" is a borrowing