Dynamics of an open basaltic magma system: The 2008 activity of the Halema‘uma‘u Overlook vent, Kīlauea Caldera

Eychenne, Julia; Houghton, B. F.; Swanson, Donald A.; Carey, Rebecca J.; Swavely, Lauren

doi:10.1016/j.epsl.2014.10.045

Cited by 18 publications

(8 citation statements)

References 37 publications

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“…As a result, monitoring of textures and petrochemical properties of lava fragments and pyroclasts is now routinely carried out on a daily basis at active volcanoes such as Kīlauea, Etna, and Stromboli (e.g. Taddeucci et al, 2002;Thornber et al, 2003;Polacci et al, 2006;Swanson et al, 2009;Colò et al, 2010;Houghton et al, 2011Houghton et al, , 2013Houghton et al, , 2016Carey et al, 2012Carey et al, , 2013Lautze et al, 2012;Andronico et al, 2013aAndronico et al, , b, 2014Corsaro and Miraglia, 2014;Di Muro et al, 2014;Gurioli et al, 2014;Eychenne et al, 2015;Leduc et al, 2015;Kahl et al, 2015). In the past, time series of petrographic and geochemical data have been measured for Piton de la Fournaise (PdF) basalts and particularly for effusive products.…”

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confidence: 99%

Integrating field, textural, and geochemical monitoring to track eruption triggers and dynamics: a case study from Piton de la Fournaise

et al. 2018

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Abstract. The 2014 eruption at Piton de la Fournaise (PdF), La Réunion, which occurred after 41 months of quiescence, began with surprisingly little precursory activity and was one of the smallest so far observed at PdF in terms of duration (less than 2 days) and volume (less than 0.4  ×  106 m3). The pyroclastic material was composed of golden basaltic pumice along with fluidal, spiny iridescent and spiny opaque basaltic scoria. Density analyses performed on 200 lapilli reveal that while the spiny opaque clasts are the densest (1600 kg m−3) and most crystalline (55 vol. %), the golden pumices are the least dense (400 kg m−3) and crystalline (8 vol. %). The connectivity data indicate that the fluidal and golden (Hawaiian-like) clasts have more isolated vesicles (up to 40 vol. %) than the spiny (Strombolian-like) clasts (0–5 vol. %). These textural variations are linked to primary pre-eruptive magma storage conditions. The golden and fluidal fragments track the hotter portion of the melt, in contrast to the spiny fragments and lava that mirror the cooler portion of the shallow reservoir. Exponential decay of the magma ascent and output rates through time revealed depressurization of the source during which a stratified storage system was progressively tapped. Increasing syn-eruptive degassing and melt–gas decoupling led to a decrease in the explosive intensity from early fountaining to Strombolian activity. The geochemical results confirm the absence of new input of hot magma into the 2014 reservoir and confirm the emission of a single shallow, differentiated magma source, possibly related to residual magma from the November 2009 eruption. Fast volatile exsolution and crystal–melt separation (second boiling) were triggered by deep pre-eruptive magma transfer and stress field change. Our study highlights the possibility that shallow magma pockets can be quickly reactivated by deep processes without mass or energy (heat) transfer and produce hazardous eruptions with only short-term elusive precursors.

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confidence: 99%

Integrating field, textural, and geochemical monitoring to track eruption triggers and dynamics: a case study from Piton de la Fournaise

et al. 2018

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“…Vesicles in magma (particularly basaltic) are generally small and rare at depths greater than several hundred metres below the surface at the time of dike emplacement (Galindo and Gudmundsson 2012;Gudmundsson 2016). Also, measurements in Hawaii suggest that most of the exsolution of gas in basaltic magmas occurs in the uppermost few hundred metres of the feeder/conduit (Greenland et al 1988;Eychenne et al 2015;Ferguson et al 2016;Moussallam et al 2016). Thus, the expected reduction in magma density due to gas expansion is unlikely to be of great significance, if at all, except very close to the surface.…”

Section: Magmatic Overpressure and Depth Of Magma Sourcementioning

confidence: 99%

Depths of magma chambers at three volcanic provinces in the Karlıova region of Eastern Turkey

et al. 2018

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The size of a volcanic eruption, and thus the associated potential hazards, depends partly on the depth, geometry, and size of the source magma chamber. To estimate magma chamber depths and sizes, we apply a newly developed analytical method, based on the aspect ratio (length/thickness) of dikes, to three volcanoes in the Karlıova region of Eastern Turkey, namely Turnadağ, Varto, and Özenç. The results indicate that the depths of the source chambers are between 2 and 4 km at Turnadağ, 2 to 5 km at Varto, both of which are located in transtensional tectonic regimes, but from 22 to 27 km at Özenç, which is located in a convergent tectonic regime. A similar reservoir depth at Özenç is indicated by seismic tomography, and this data also suggests that the reservoir is laterally continuous for more than 40 km. The large volume of ignimbrites (>40 km 3) associated with Varto, a collapse caldera, indicates that caldera subsidence may have maintained the excess magmatic pressure (through tectonic forcing) in the chamber over a longer time than during normal pyroclastic eruptions. The dike aspect ratios further indicate magmatic overpressures of 13-21 MPa for Varto, 13-17 MPa for Turnadağ, and 26-31 MPa for Özenç. The combined results from seismic tomography, analytical models and magma compositions indicate that both Turnadağ and Varto volcanoes, which are typical stratovolcanoes composed of mostly intermediate, and more rarely, acidic magmas, were fed by two very shallow and comparatively small magma chambers (2-5 km depth). Whereas less evolved magmas were erupted from Özenç, which hosts predominantly basaltic and intermediate lavas and dikes that were fed by a deep reservoir at 22-27 km depth. Our tomographic models show that none of the volcanoes are located directly over the centre of a deep magma reservoir. Our data also indicates that the magma in the reservoir has migrated between 34 and 40 km in a right lateral motion (to the east) below Varto and Turnadağ, respectively, and 23 km in a left lateral motion (to the west) at Özenç over the past 3 Ma. This lateral propagation of magma can be explained by tectonic escape of the Anatolian block to the west through the Northern Anatolian Fault and the Varto Fault Zone over the last 6 Ma.

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“…This convection and associated gas loss through the surface, once cross-sectionally averaged, would increase density, bulk modulus, and sound speed in the upper part of the conduit relative to the magmastatic model ( § 2.4). Indeed, inferred values of density in the Kilauea lava lake from continuous gravity (Carbone et al 2013) and direct measurement of near-surface samples (Eychenne et al 2015) are in the range 400-1000 kg m − 3.…”

Section: Discussionmentioning

confidence: 99%

“…For example, the most recent phase of eruptive activity at Kilauea Volcano, Hawaii, is characterized by intermittent degassing bursts through a vent in Halema'uma'u crater (Wilson et al 2008), which are accompanied by ∼30 s oscillations (termed very long period or VLP oscillations) recorded on nearby broadband seismometers . Many degassing bursts are triggered by rockfalls (Carey et al 2012;Dawson & Chouet 2014;Eychenne et al 2015), which impulsively excite oscillations that ring down over several minutes. Similar VLP oscillations observed at Mount Erebus, Antarctica, had periods ∼10-20 s and also lasted for a few minutes (Aster et al 2003).…”

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Excitation and resonance of acoustic-gravity waves in a column of stratified, bubbly magma

Karlstrom

Dunham

2016

J. Fluid Mech.

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Oscillations of magma in volcanic conduits are thought to be the source of certain seismic and infrasonic signals observed near active volcanoes. However, the multiphase and stratified nature of magma within the conduit complicates the calculation of resonant modes that is required to interpret observations. Here we present a linearized mathematical framework to describe small-amplitude oscillations and waves in a stably stratified column of two-phase magma (liquid melt and gas bubbles) with a traction-free upper surface (a lava lake). We explore the role of time-dependent mass exchange between the phases, depth-varying fluid properties and gravity on the modes of oscillation of inviscid magma within an axisymmetric, vertical conduit. Non-equilibrium phase exchange, which we refer to as bubble growth and resorption (BGR), is parameterized by introduction of a kinetic time scale quantifying mass exchange between the liquid and gas phases that evolves the mixture towards a state of thermodynamic equilibrium. Using a provably stable finite difference method, we solve the eigenvalue problem for the resonance frequencies, decay rates, and spatial structure of the conduit eigenmodes. The numerical method is then extended to time-domain simulations of waves excited by internal volumetric sources in the conduit or forces applied to the surface of the lava lake. We connect time-dependent wave propagation simulations to the modal analysis by identifying the primary modes that are excited by representative excitation processes. Waves propagating through bubbly magma are dispersive, and their behaviour is determined by three dimensionless parameters. One quantifies the importance of buoyancy and gravitational restoring forces relative to compressibility, the second quantifies differences between fluid properties (e.g. mixture compressibility) under equilibrium and non-equilibrium conditions, and the third compares the wave period to the BGR time scale. Pronounced depth variations in background fluid properties, such as the transition from liquid melt with dissolved volatiles at the high pressures at depth to bubbly magma above the gas exsolution depth, segment the conduit into distinct regions. The longest-period modes, which are expressed with the largest amplitudes for typical excitation processes, are most sensitive to the length of the bubbly region and properties of the bubbly magma within it. While the boundary condition at the bottom of the conduit determines whether the fundamental mode is affected by the total conduit length, modes localized above the exsolution depth are remarkably insensitive to the overall conduit length. Our analysis suggests that parameters affecting eruption style, such as total volatile content and kinetic time scales of BGR, along with excitation source characteristics, are imprinted on long-period seismic and infrasonic signals at active volcanoes.

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Dynamics of an open basaltic magma system: The 2008 activity of the Halema‘uma‘u Overlook vent, Kīlauea Caldera

Cited by 18 publications

References 37 publications

Integrating field, textural, and geochemical monitoring to track eruption triggers and dynamics: a case study from Piton de la Fournaise

Integrating field, textural, and geochemical monitoring to track eruption triggers and dynamics: a case study from Piton de la Fournaise

Depths of magma chambers at three volcanic provinces in the Karlıova region of Eastern Turkey

Excitation and resonance of acoustic-gravity waves in a column of stratified, bubbly magma

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