Geology glossary

During a Hawaiian eruption, very fluid, basaltic lava is erupted from the vent as lava fountains and forms lava flows. The fountains are driven by the expanding gasses that were contained in the magma and leave the vent as a jet. Such eruptions are common for hot-spot volcanoes such as Kilauea on Hawai'i.

The lava fountains can reach heights of several hundreds meters, sometimes even more than 1 km. They can last for hours or even days and often occur from fissure vents to form so-called curtains of fire.

The lava spatter that falls back from the fountain can form lava flows if it is still fluid enough, or build up welded spatter ramparts and cinder cones around the vent. Along with the lava fountains, a portion of already degassed magma leaves the vent directly as lava flows, and lava effusion without fountaining can continue after the fountaining phase for a long time (at Pu'u 'O'o, lava effusion essentially has been continuing for more than 30 years now).

Because the lava during Hawaiian eruptions is very fluid, it can form rivers of lava of several kilometers length.



Hawaiian eruptions have their names from Kilauea and Mauna Loa volcanoes on the Big Island of Hawaii, which have produced spectacular lava fountains, but they also occur on other volcanoes, most notably on Piton de la Fournaise volcano on La Réunion island (Indian Ocean, France) and on Etna and Vesuvius volcanoes, both in Italy.

Some of the most spectacular Hawaiian eruptions on Hawaii were the the 1959 eruption of the Kilauea Iki Crater at the summit of Kilauea, and the 1969-1974 Mauna Ulu eruption and 1983-1986 Pu'u 'O'o eruptions both on the eastern rift zone of Kilauea.