AGU: Birth Of A Hawaiian Fissure Eruption

A fountaining eruption of Hawaii’s Kilauea volcano, which occurred May 5, 2018. Courtesy/AGU

AGU News:

Ready for a new kind of holiday yule log? Then this mesmerizing video of an erupting volcano is for you.

This spectacular footage captures a fountaining eruption of Hawaii’s Kilauea volcano May 5, 2018. The eruption went through several phases:

  • First, there were pulsing bursts of escaping volcanic gas;
  • Next, closely spaced weak explosions of particles torn from magma in the volcanic vent; and
  • Last, weak incandescent fountaining of particles and gas.

Researchers analyzed the footage in a new study in AGU’s Journal of Geophysical Research: Solid Earth. Play the footage for family and friends during the holidays for a fun, science-themed gathering. Watch a long version of this video here:

Abstract 

Most basaltic explosive eruptions intensify abruptly, allowing little time to document processes at the start of eruption. One opportunity came with the initiation of activity from fissure 8 (F8) during the 2018 eruption on the lower East Rift Zone of Kīlauea, Hawaii. F8 erupted in four episodes.

We recorded 28 minutes of high‐definition video during a 51‐minute period, capturing the onset of the second episode May 5.

From the videos we were able to analyze the following in‐flight parameters: frequency and duration of explosions; ejecta heights; pyroclast exit velocities; in‐flight total mass and estimated mass eruption rates; and the in‐flight total grain size distributions.

Videos record a transition from initial pulsating outgassing, via spaced, but increasingly rapid, discrete explosions, to quasi‐sustained, unsteady fountaining. This transition accompanied waxing intensity (mass flux) of the F8 eruption. We infer that all activity was driven by a combination of the ascent of a coupled mixture of small bubbles and melt, and the buoyant rise of decoupled gas slugs and/or pockets.

The balance between these two types of concurrent flow determined the exact form of the eruptive activity at any point in time, and changes to their relative contributions drove the transition we observed at early F8. Qualitative observations of other Hawaiian fountains at Kīlauea suggest that this physical model may apply more generally.

This study demonstrates the value of in‐flight parameters derived from high resolution videos, which offer a rapid and highly time‐sensitive alternative to measurements based on sampling of deposits post‐eruption.

Plain Language Summary

We recorded the ‘birth’ of a ‘fountaining’ eruption of Kīlauea volcano May 5, 2018, using a high resolution camera. The eruption passed from (1) pulsing escape of bursts of volcanic gas to (2) numerous close‐spaced weak explosions ejecting particles torn from the magma (molten rock) in the vent, to (3) weak incandescent fountaining of particles and gas.

Initially the behavior was dominated by meter‐sized gas bubbles escaping freely through slow‐rising magma beneath the vent. Rise of the magma and its mechanically coupled smaller bubbles played an increasing role with time and drove the switch to continuous fountaining.

Observations of many earlier Kīlauea eruptions suggest that this model may apply generally to the initiation of this spectacular form of volcanic eruption.

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