The Kulanaokuaiki-3 tephra, 900 CE: Products of a remarkably energetic pyroclastic eruption at Kīlauea Volcano, Hawaiʻi, USA

Geological Society of America Bulletin
By: , and 

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Abstract

Eruptions of Kīlauea Volcano, Hawaiʻi, USA, can be more powerful than previously recognized. The Kulanaokuaiki-3 (K-3) eruption, ca. 900 CE, consisted of two episodes that dispersed lithic wall-rock clasts (Episode 1) and dominantly scoria (Episode 2; VEI-3) across >65 km2 southeast of the summit. Dense 12 cm blocks of Episode 1 fell 8–10 km from the summit vent, and 2–4 cm lithic lapilli reached the coastline, 17 km from the vent. The Episode 2 deposit is chemically zoned, indicating orderly eruption from a layered magma body analogous to the 1959 Kīlauea Iki lava lake. Olivine-hosted melt inclusions suggest a magma body within 1 km of the surface. Some Episode 1 lithic clasts have magmatic rinds chemically similar to the early Episode 2 scoria, suggesting a genetic link, although each had a distinct eruption mechanism. Southeastward tephra dispersal counter to NE trade winds implies dispersal by jet-stream winds. The dispersal of lithic clasts in Episode 1 cannot be explained by ballistic trajectories or by transport in a buoyant plume. Calculations instead indicate that a jet from a vent with a minimum diameter of 50 m, a velocity of at least 300 m/s, and a duration of ∼60 s could have lifted the lithic clasts into the jet stream. Isopach and isopleth maps for Episode 2 indicate a subplinian column height of 14–18 km and a duration of 2–3 h, assuming constant flux. The Episode 1 conduit probably intersected or otherwise lowered pressure within a compositionally zoned magma body, triggering eruption of the Episode 2 scoria.

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Publication type Article
Publication Subtype Journal Article
Title The Kulanaokuaiki-3 tephra, 900 CE: Products of a remarkably energetic pyroclastic eruption at Kīlauea Volcano, Hawaiʻi, USA
Series title Geological Society of America Bulletin
DOI 10.1130/B35063.1
Volume 131
Issue 9-10
Year Published 2019
Language English
Publisher Geological Society of America
Contributing office(s) Volcano Science Center
Description 18 p.
First page 1537
Last page 1554
Country United States
State Hawaii
Other Geospatial Kīlauea Volcano
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