The Birth of a Hawaiian Fissure Eruption

Abstract

Introduction 1.1. Basaltic Explosive Eruptions Weak (or "mild") basaltic explosive eruptions are highly dynamic, showing shifts in style and particularly intensity on timescales of minutes to hours (e.g.,

Inflated pyroclasts in proximal fallout deposits reveal abrupt transitions in eruption behaviour

“…Inflated pyroclasts may form instead of scoria if the lava fountain temporarily pauses or stops and the eruptive activity transitions to low-energy bubble bursts 63 (similar to bubble bursting at a lava lake or very weak Strombolian activity). Such eruptive behaviour transitions are not unprecedented and similar abrupt (but regular) changes in eruptive activity have been witnessed during the 2021 eruption of Fagradalsfjall, Iceland and during the 2018 eruption of Kīlauea, Hawaii 21 . The cause of such transitions remains uncertain, but it is likely due to reorganisation of gas in the shallow volcanic plumbing system.…”

“…Explosive activity at mafic volcanoes, especially in its milder forms (i.e., lava fountaining, spattering events and discrete bubble bursts) can be highly variable in its surface expression 18 – 20 . Eruption intensities and styles of activity can also fluctuate over short timescales and distances 21 , 22 —this presents challenges to hazard management 23 and hinders systematic observation of eruptive phenomena. Fluctuations in intensity and style can occur between eruptive episodes, within a single episode, and simultaneously at different spatial locations 21 .…”

“…Eruption intensities and styles of activity can also fluctuate over short timescales and distances 21 , 22 —this presents challenges to hazard management 23 and hinders systematic observation of eruptive phenomena. Fluctuations in intensity and style can occur between eruptive episodes, within a single episode, and simultaneously at different spatial locations 21 . Furthermore, the physical processes governing explosive eruption of low viscosity magmas are fundamentally different to those operating in the now relatively well-studied silicic systems 24 – 27 .…”

Conduit formation and crustal microxenolith entrainment in a basaltic fissure eruption: Observations from Thríhnúkagígur Volcano, Iceland

“…Vesicles are observed in both the interior and quenched margin of the dike but are more common in the interior. A large gas pocket "froze" in the center of the main dike, capturing the annular flow consistent with Hawaiian to Strombolian style eruptions (Figure 6A; Houghton et al [2021]).…”

Crowd-sourcing observations of volcanic eruptions during the 2021 Fagradalsfjall and Cumbre Vieja events

“…2 ). Such qualitative observations, particularly when coupled with quantitative observations of fountain steadiness, periodicity, and height, provide new evidence to inform conceptual models of the role of decoupled gas and magma flux in controlling the dynamics of lava effusion and fountaining 10 , 11 .…”