Geology topics

Jacopo Taddeucci

Publications and source records attributed to Jacopo Taddeucci.

4 recordsLinked to original sources

USGS2021

Patterns of bubble bursting and weak explosive activity in an active lava lake—Halema‘uma‘u, Kīlauea, 2015

The rise of the Halemaʻumaʻu lava lake in 2013–2018 to depths commonly 40 meters or less below the rim of the vent was an excellent opportunity to study outgassing and the link to associated eruptive activity. We use videography to investigate the rise and bursting of bubbles through the free surface of the lake in 2015. We focus on low-energy explosive activity (spattering) in which the ascent and bursting of meter-sized, mechanically decoupled bubbles trigger the ejection of fluidal bombs to tens of meters above the free surface. A decay in initial pyroclast velocity with time follows the same functional form as that observed for ejecta at Stromboli (Italy), suggesting a similar bubble-burst mechanism. We also find that the upward velocity of the bubble crust as it bursts is around 2.5 times higher than the velocity of the bubble as it rises through the lake surface, indicating that the bubbles are over-pressurized. Prior to bursting, bubbles emerge at velocities of 4 to 14 meters per second, suggesting rise from depths of at least tens of meters but unaffected by the deeper circulation of the lava lake. We identify three styles of bubble bursting: (1) isolated, widely spaced, single bursts, (2) recurring clusters of discrete bubbles, and (3) prolonged episodes of overlapping bubble bursts along elongate narrow sources typically parallel to the margins of the lava lake. We call these styles of bursting isolated events, clusters, and prolonged episodes, respectively. The frequency of bubble bursting and the mass fluxes of gas and pyroclasts increase from styles 1 to 3. The intensity (mass eruption rate) for single bubble bursts ranges from 280 to 3,500 kilograms per second. The total erupted mass of pyroclasts for a single burst is <4,000 kilograms (kg) and for a single well-constrained prolonged episode is about 10 7 kg. These numbers place the observed spattering at the lowest end of basaltic explosivity in terms of erupted mass (that is, magnitude). Most ejecta fell back into the crater; only strands of Pele’s hair rose to heights where they could be advected downwind from the vent. Collectively, the explosive activity accompanying the three styles of bubble bursting spans from impulsive, transient eruptive behaviors to sustained discharge; this shift represents progressively higher frequency and intensity of bubble bursting.

Hawaii↗

USGS2021

The birth of a Hawaiian fissure eruption

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 min of high‐definition video during a 51‐min period, capturing the onset of the second episode on 5 May. 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. The videos record a transition from initial pulsating outgassing, via spaced, but increasingly rapid, discrete explosions, to quasisustained, 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 posteruption.

Island of Hawai'i↗

USGS2017

Integrating puffing and explosions in a general scheme for Strombolian-style activity

Strombolian eruptions are among the most common subaerial styles of explosive volcanism worldwide. Distinctive features of each volcano lead to a correspondingly wide range of variations of magnitude and erupted products, but most papers focus on a single type of event at a single volcano. Here, in order to emphasize the common features underlying this diversity of styles, we scrutinize a database from 35 different erupting vents, including 21 thermal infrared videos from Stromboli (Italy), Etna (Italy), Yasur (Vanuatu), and Batu Tara (Indonesia), from puffing, through rapid explosions to normal explosions, with variable ejection parameters and relative abundance of gas, ash, and bombs. Using field observations and high-speed thermal infrared videos processed by a new algorithm, we identify the distinguishing characteristics of each type of activity and how they may relate and interact. In particular, we record that ash-poor normal explosions may be preceded and followed by the onset or the increase of the puffing activity, while ash-rich explosions are emergent, i.e., with inflation of the free surface followed directly by emission of increasingly large gas pockets. Overall, we see that all Strombolian activities form a continuum arising from a common mechanism and are modulated by the combination of two well-established controls: (1) the length of the bursting gas pocket with respect to the vent diameter and (2) the presence and thickness of a high-viscosity layer in the uppermost part of the volcanic conduit.

Journal of Geophysical Research B: Solid Earth↗

USGS2016

Stronger or longer: Discriminating between Hawaiian and Strombolian eruption styles

The weakest explosive volcanic eruptions globally, Strombolian explosions and Hawaiian fountaining, are also the most common. Yet, despite over a hundred years of observations, no classifications have offered a convincing, quantitative way of demarcating these two styles. New observations show that the two styles are distinct in their eruptive timescale, with the duration of Hawaiian fountaining exceeding Strombolian explosions by about 300 to 10,000 seconds. This reflects the underlying process of whether shallow-exsolved gas remains trapped in the erupting magma or whether it is decoupled from it. We propose here a classification scheme based on the duration of events (brief explosions versus prolonged fountains) with a cutoff at 300 seconds that separates transient Strombolian explosions from sustained Hawaiian fountains.

Geology↗