Volcano Eruptions Types

Volcano Eruptions Types

Volcanologist use six different terms to describe an explosive event from a volcano, Fissure, Hawaiian, Strombolian, Vulcanian, Plinian (Vesuvian) and Hydrovolcanic (Surtseyan) eruptions. These eruptions are categorized by the height that the ash or volcanic material travels upward and how powerful the explosion was when the volcano erupted. The least powerful of them all is the Hawaiian eruption which is mainly produced by shield volcanoes that have low gas levels within the lava. Without the high gas levels the explosiveness of the event is relatively quiet with the lava flowing quickly through lava channels and tunnels from the crater to lower points around the base. Occasionally the eruptions do produce pyroclastic discharges but they are not violent in nature.

Fissure eruptions are similar to Hawaiian eruptions in that they produce low explosive events and lava flows that travel along the sides of the volcano.

Strombolian eruptions are a little more violent and produce more frequent eruption discharges than do Hawaiian eruptions. It was named for a scoria volcano located on the island of Stromboli off the coast of Italy which erupts on a daily bases. With the build of gas in the lava these eruptions are very short in duration and may throw rocks and lava high into the air, sometimes more than 10 km, which cools very rapidly and does not produce flows of lava like the Hawaiian eruption.

Vulcanian eruptions are produced when the pressure inside the volcano builds up but cannot be released because of the high viscosity of the lava with it. When the pressure is finally enough to break through the lava the eruption occurs with violent force which is generally short lived throwing clouds of ash upwards of 10 km into the atmosphere. These eruptions produce large pyroclastic chunks that are not distributed far from the crater because of their weight.

Plinian