World’s longest volcanic eruption
Tomorrow marks the 28th anniversary of the eruption of Kīlauea Volcano, the world’s longest continuous eruption. The volcano is located in Hawaii Volcanoes National Park and is the most recent of the volcanos that formed the Hawaiian archipelago. The east rift zone erupted on Jan. 3, 1983, and has continued uninterrupted ever since. A second, simultaneous eruption began at Kīlauea’s summit on March 19, 2008. The Hawaiian Volcano Observatory (the “HVO”), with other organizations, plans lectures, tours and other activities to mark the occasion throughout January.
The HVO is part of the Volcano Hazards Program of the U.S. Geological Survey (the “USGS”), which conducts research on Hawaiian volcanoes and works with local responders in emergency situations.
Kīlauea is one of five shield volcanoes that make up the island of Hawaii. It began erupting 600,000 to 300,000 years ago and has been active ever since. According to the HVO, “Kīlauea is made mostly of lava flows, locally interbedded with deposits of explosive eruptions.” It’s had three sources of eruption: the summit and two rift zones. Currently at the summit there is a caldera, which has existed for several thousand years at least. The summit is the single location where the most frequent eruptions take place. Along the rift zones, however, more eruptions take place, but they are not localized.
The current eruption, called the Pu`u `Ō `ō-Kupaianaha eruption of Kīlauea, marks the 55th eruptive episode and ranks as the most voluminous outpouring of lava on the volcano’s east rift zone in the past five centuries. The image below, by the USGS, is a photograph overlain with a thermal image taken on October 28, 2010. The lava flows in underground tubes to the ocean. Occasionally, as in the marked areas in the photo, there are active breakouts. The tube system is usually buried sufficiently to prevent thermal detection. There is a signature, however, in this photo near the ocean. According to the USGS: “The large area of purple and red colors in the foreground shows the flows emplaced in July and August of this year. These recent flows are inactive but still warm.”
The cut-away below hosted by the HVO shows the underground vein supplying the lava for the eruption of Pu`u `O`o on the east rift zone about 20 km from the caldera as well as the tube system to the ocean.
When there is an eruption at Pu`u `O`o, magma either flows to the surface there or flows through the tube system to the sea.
The episode 54 fissure marked on the cutaway refers to an eruption on January 30, 1997, Napau Crater about 4 km uprift from Pu`u `O`o. The rift zone widened about 1.8 m in Napau as magma forced a pathway to the surface.