Submarine Explosive Eruptions

White, James D. L.; Schipper, C. Ian; Kano, Kazuhiko

doi:10.1016/b978-0-12-385938-9.00031-6

Cited by 37 publications

(33 citation statements)

References 20 publications

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“…In some cases, weak explosive eruptions may occur at water depths from 1500 to 500 m, while more intense explosive eruptions can occur at depths <500 m (Cas, 1992;Fiske et al, 1998;White et al, 2015b), but only if the volatile content, strain rate affecting magma in the conduit and gas over-pressures are high enough. Otherwise, coherent lavas, including highly vesicular pumice lavas, can form, as occurred during the 2012 submarine Havre eruption (Carey et al, 2018;Ikegami et al, 2018;Manga et al, 2018).…”

Section: Confining (Hydrostatic) Pressure and The Physical State And mentioning

confidence: 99%

Why Deep-Water Eruptions Are So Different From Subaerial Eruptions

Raymond

Simmons

2018

Front. Earth Sci.

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Magmas erupted in deep-water environments (>500 m) are subject to physical constraints very different to those for subaerial eruptions, including hydrostatic pressure, bulk modulus, thermal conductivity, heat capacity and the density of water mass, which are generally orders of magnitude greater than for air. Generally, the exsolved volatile content of the erupting magma will be lower because magmas decompress to hydrostatic pressures orders of magnitude greater than atmospheric pressure. At water depths and pressures greater than those equivalent to the critical points of H 2 O and CO 2 , exsolved volatiles are supercritical fluids, not gas, and so have limited ability to expand, let alone explosively. Gas overpressures are lower in deep submarine magmas relative to subaerial counterparts, limiting explosive expansion of gas bubbles to shallower waters. Explosive intensity is further minimized by the higher bulk modulus of water, relative to air. Higher retention of volatiles makes subaqueously erupted magmas less viscous, and more prone to fire fountaining eruption style compared with compositionally equivalent subaerial counterparts. The high heat capacity and thermal conductivity of (ambient) water makes effusively (and/or explosively) erupted magmas more prone to rapid cooling and quench fragmentation, producing non-explosive hyaloclastite breccia. Gaseous subaqueous eruption columns and hot water plumes form above both explosive and non-explosive eruptions, and these can entrain pyroclasts and pumice autoclasts upward. The height of such plumes is limited by the water depth and will show different buoyancy, dynamics, and height and dispersal capacity compared with subaerial eruption columns. Water ingress and condensation erosion of gas bubbles will be major factors in controlling column dynamics. Autoclasts and pyroclasts with an initial bulk density less than water can rise buoyantly, irrespective of plume buoyancy, which they cannot do in the atmosphere. Dispersal and sedimentation of clasts in water is affected by the rate at which buoyant clasts become waterlogged and sink, and by wind, waves, and oceanic currents, which can produce very circuitous dispersal patterns in floating pumice rafts. Floating pumice can abrade by frictional interaction with neighbors in a floating raft, and generate in transit, post-eruptive ash fallout unrelated to explosive activity or quench fragmentation.

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Section: Confining (Hydrostatic) Pressure and The Physical State And mentioning

confidence: 99%

Why Deep-Water Eruptions Are So Different From Subaerial Eruptions

Raymond

Simmons

2018

Front. Earth Sci.

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“…Surtseyan volcanic eruption style refers to magma interacting with any standing water body (lakes, rivers, marine) [53]. The water depth in a Surtseyan eruption should be shallower than the water mass required to suppress the explosive expansion of fragmented pyroclasts to the shallow range where the explosive energy completely displaces the overlying water by generating a near-vent environment essentially the same as in subaerial conditions [47,[54][55][56][57][58][59][60][61].…”

Section: Introduction: Historic Perspective and Definitionsmentioning

confidence: 99%

Review of Explosive Hydrovolcanism

Németh

Kósik

2020

Geosciences

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Hydrovolcanism is a type of volcanism where magma and water interact either explosively or non-explosively. The less frequently used term, hydromagmatism, includes all the processes responsible for magma and water interaction in a magmatic system. Hydrovolcanism is commonly used as a synonym for phreatomagmatism. However, in recent years phreatomagmatism appears more in association with volcanic eruptions that occur in shallow subaqueous or terrestrial settings and commonly involves molten fuel-coolant interaction (MFCI) driven processes. Here a revised and reviewed classification scheme is suggested on the basis of the geo-environment in which the magma-water interaction takes place and the explosivity plus mode of energy transfer required to generate kinetic energy to produce pyroclasts. Over the past decade researchers have focused on the role hydrovolcanism/phreatomagmatism plays in the formation of maar craters, the evolution of diatremes and the signatures of magma—water interaction in the geological record. In the past five years, lithofacies-characterization is the most common approach to studying hydrovolcanism. By far mafic monogenetic volcanic fields generated the greatest number of research results. Significant knowledge gaps are identified, especially in developing tools to identify the textural signatures hydrovolcanism leave behind on eruptive products and exploring the role of hydrovolcanism in the growth of intermediate and silicic small volume volcanoes.

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“…Eruption into a deep subaqueous environment is complex. In addition to influences of magma composition and rheology (Walker and Croasdale, 1971;Dingwell and Webb, 1990), volatile content of the magma, and magma flux (Gonnermann and Manga, 2003;Namiki and Manga, 2008), submarine eruptions are significantly modulated by the physical properties of water, both indirectly (hydrostatic pressure, increased viscosity of water relative to air) and directly (rapid heat transfer, rapid volume expansion of vaporized seawater) (Head and Wilson, 2003;White et al, 2003White et al, , 2015Cas and Giordano, 2014). Hydrostatic pressure will suppress the magnitude of volatile exsolution and expansion, and is presumed to limit explosive expansion and related fragmentation (Fisher, 1984;Staudigel and Schmincke, 1984).…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Deposit Stratigraphy of Submarine-Erupted Silicic Ash, Havre Volcano, Kermadec Arc, New Zealand

2019

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Submarine eruptions dominate volcanism on Earth, but few are observed or even identified. Knowledge of how they operate is largely based on inference from ancient deposits, lagging by a decade or more our understanding of subaerial eruptions. In 2012, the largest wholly deep-subaqueous silicic eruption with any observational record occurred 700-1220 m below sea level at Havre volcano, Kermadec Arc, New Zealand. Pre-and post-eruption shipboard bathymetry surveys, acquisition by autonomous underwater vehicle of meter-scale-resolution bathymetry, and sampling by remote-operated vehicle revealed 14 seafloor lavas and three major seafloor clastic deposits. Here we analyze one of these clastic deposits, an Ash with Lapilli (AL) unit, which drapes the Havre caldera, and interpret the fragmentation and dispersal processes that produced it. Seafloor images of the unit reveal multiple subunits, all ash-dominated. Sampling destroyed layering in all but two samples, but by combining seafloor imagery with granulometry and componentry, we were able to determine the subunits' stratigraphy and spatial extents throughout the study area. Five subunits are distinguished; from the base these are Subunit 1, Subunit 2a, Subunit 3, Subunit 4 (comprising the coeval Subunit 4 west and Subunit 4 east), and Subunit 2b. The stratigraphic relationships of the four AL unit subunits to other seafloor products of the 2012 Havre eruption, coupled with the wealth of remote-operated vehicle observations and detailed AUV bathymetry, allow us to infer the overall order of events through the eruption. Ash formed by explosive fragmentation of a glassy vesicular magma and was dispersed by a buoyant thermal plume and dilute density currents from which Subunits 1 and 2 were deposited. Following a time break (days/weeks?), effusion of lava along the southern caldera rim led to additional ash generation; first by syn-extrusive ash venting, quenching, brecciation, and comminution (S3 and S4e) and then by gravitational collapse of a dome (S4w). Slow deposition of extremely fine ash sustained S2 deposition across the times of S3 and S4 emplacement, so that S2 ash was the last deposited. These thin ash deposits hold information critical for interpretation of the overall eruption, even though they are small in volume and bathymetrically unimpressive. Ash deposits formed during other submarine eruptions are similarly likely to offer new perspectives on associated lavas and coarse pumice beds, both modern and ancient, and on the Frontiers in Earth Science | www.frontiersin.org 1 January 2019 | Volume 7 | Article 1Murch et al.Ash With Lapilli Unit at Havre Volcano eruptions that formed them. Submarine ash is widely dispersed prior to deposition, and tuff is likely to be the first product of eruption identified in reconnaissance exploration; it is the start of the trail to vent hydrothermal systems and associated mineralized deposits of submarine volcanoes, as well as a sensitive indicator of submarine eruptive processes.

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Submarine Explosive Eruptions

Cited by 37 publications

References 20 publications

Why Deep-Water Eruptions Are So Different From Subaerial Eruptions

Why Deep-Water Eruptions Are So Different From Subaerial Eruptions

Review of Explosive Hydrovolcanism

Characteristics and Deposit Stratigraphy of Submarine-Erupted Silicic Ash, Havre Volcano, Kermadec Arc, New Zealand

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