Explosive eruptions of Kilauea Volcano, Hawaii

Decker, Robert W.
Christiansen, Robert L.
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National Academy Press
Although most Kilauea eruptions produce effusive basaltic lavas, about 1 percent of the prehistoric and historical eruptions have been explosive. Multiple steam explosions from Halemaumau Crater in 1924 followed subsidence of an active lava lake. A major hydromagmatic explosive eruption in 1790 deposited most of the Keanakakoi Formation-a blanket of pumice, vitric ash, and lithic tephra that is locally more than 10m thick around Kilauea's summit area. The Keanakakoi was deposited in multiple air•fall and pyroclastic-surge phases, probably accompanied by caldera subsidence. The Uwekahuna Ash, exposed near the base of the present caldera cliffs and on the southeast flank of Mauna Loa, was formed by a major sequence of explosive eruptions about 1500 yr before present (B.P.). Beneath the Vwekahuna Ash in a few localities are two to three similar pyroclastic deposits. The Pahala Ash, extensive on the south flank of Kilauea and on adjacent Mauna Loa, reflects many explosive eruptions from about 25,000 to 10,000 yr B.P. Although it is not clear whether parts of the much weathered and reworked Pahala are of lava-fountain or hydromagmatic origin, much of it appears to be hydromagmatic. Pyroclastic deposits are present in the Hilina Formation on the south flank of Kilauea near the coast; about six of these deposits are estimated to be 40,000 to 50,000 yr old, and others are both younger and older. None of the deposits older than 2000 yr is well dated, but if we assume generally uniform growth rates for Kilauea's shield during the past 100,000 yr, an average, but not periodic, recurrence of major explosive eruptions is about every 2000 yr; minor explosive eruptions may be more frequent. The occurrence of relatively rare but dangerous explosive eruptions probably relates to sudden disruptions of equilibrium between subsurface water and shallow magma bodies, triggered by major lowering of the magma column.
hazards, Kilauea, Kilauea Crater, Hawaii
Decker RW, Christiansen RL. 1984. Explosive eruptions of Kilauea Volcano, Hawaii. Washington D.C.: National Academy Press.
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