Cycles of explosive and effusive eruptions at Kīlauea Volcano, Hawai‘i

Abstract

The subaerial eruptive activity at Kīlauea Volcano (Hawai'i) for the past 2500 yr can be divided into 3 dominantly effusive and 2 dominantly explosive periods, each lasting several centuries. The prevailing style of eruption for 60% of this time was explosive, manifested by repeated phreatic and phreatomagmatic activity in a deep summit caldera. During dominantly explosive periods, the magma supply rate to the shallow storage volume beneath the summit dropped to only a few percent of that during mainly effusive periods. The frequency and duration of explosive activity are contrary to the popular impression that Kīlauea is almost unceasingly effusive. Explosive activity apparently correlates with the presence of a caldera intersecting the water table. The decrease in magma supply rate may result in caldera collapse, because erupted or intruded magma is not replaced. Glasses with unusually high MgO, TiO 2 , and K 2 O compositions occur only in explosive tephra (and one related lava fl ow) and are consistent with disruption of the shallow reservoir complex during caldera formation. Kīlauea is a complex, modulated system in which melting rate, supply rate, conduit stability (in both mantle and crust), reservoir geometry, water table, and many other factors interact with one another. The hazards associated with explosive activity at Kīlauea's summit would have major impact on local society if a future dominantly explosive period were to last several centuries. The association of lowered magma supply, caldera formation, and explosive activity might characterize other basaltic volcanoes, but has not been recognized.

Tephra without Borders: Far-Reaching Clues into Past Explosive Eruptions

“…explosive eruptions was the prevailing style for 60% of eruptions in the last 2500 years (Swanson et al, 2014).…”

Magma decompression rates during explosive eruptions of Kīlauea volcano, Hawaii, recorded by melt embayments

“…Furthermore, at some volcanoes, such as Kīlauea, there is evidence for past explosive eruptions that have no historically observed equivalent in intensity (e.g. Swanson et al, 2012Swanson et al, , 2014May et al, 2015) and the conditions that accompany such intensely explosive eruptions remain largely unresolved. Since a number of important processes are directly dependent on the decompression rate, such as bubble nucleation, bubble growth, and fragmentation itself (Parfitt and Wilson, 1995;Mangan and Cashman, 1996;Mangan et al, 2014;Gonnermann, 2015), robust constraints on this parameter will enable a fuller understanding of the processes that determine the intensity of explosive eruptions driven by magmatic volatiles.…”

VOLCANS: an objective, structured and reproducible method for identifying sets of analogue volcanoes

“…In historical times, phreatomagmatic and phreatic explosive eruptions have occurred (McPhie et al 1990;Dvorak 1992;Mastin et al 2004). Over a longer timescale of the past 2500 yr, Swanson et al (2014) identified several shifts between periods dominated by either effusive or explosive volcanic activity, each of those periods lasting for several centuries. Although erupted magma volumes were significantly higher during effusive periods, the total duration of explosive periods was calculated as about 500 yr longer (Swanson et al 2014).…”