Magma production and growth of the lava dome of the Soufriere Hills Volcano, Montserrat, West Indies: November 1995 to December 1997

Sparks, R. S. J.; Young, S. R.; Barclay, Jenni; Calder, Eliza S.; Cole, Paul; Darroux, B.; Davies, M. A.; Druitt, Timothy H.; Harford, C. L.; Herd, Richard A.; James, Michael; Lejeune, Anne‐Marie; Loughlin, S. C.; Norton, G. E.; Skerrit, G.; Stasiuk, M. V.; Stevens, N. S.; Toothill, J. A.; Wadge, G.; Watts, Rob

doi:10.1029/98gl00639

Cited by 152 publications

(107 citation statements)

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“…For refilling the conduit after Explosions 3 and 4, the data suggest average conduit recharge fluxes of 5.6-7.3 m 3 s −1 , and 3.0-5.6 m 3 s −1 , respectively. These values are roughly consistent with the enhanced explosion potential noted for fluxes exceeding ∼5 m 3 s −1 [Sparks et al, 1998]. The 2003 explosions appear to be close to the end-member case of zero volatile mass transfer, where magma rising in a conduit acquires a porosity and overpressure structure that evolves to critical conditions to trigger an explosion [Melnik and Sparks, 2002;de' Michieli Vituri et al, 2008].…”

Section: Strain Analysis and Other Resultssupporting

confidence: 67%

Unique strainmeter observations of Vulcanian explosions, Soufrière Hills Volcano, Montserrat, July 2003

Voight

Hidayat

Sacks

et al. 2010

Geophysical Research Letters

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[1] Five Vulcanian explosions were triggered by collapse of the Soufrière Hills Volcano lava dome in 2003. We report strainmeter data for three explosions, characterized by four stages: a short transition between the onset of disturbance and a pronounced change in strain; a quasi-linear ramp accounting for the majority of strain change; a more gradual continued decline of strain to a minimum value; and a strain recovery phase lasting hours. Remarkable ∼800 s barometric gravity waves propagated at ∼30 m s −1 . Eruption volumes estimated from plume height and strain data are 0.32-0.42 × 10 6 , 0.26-0.49 × 10 6 , and 0.81-0.84 × 10 6 m 3 , for Explosions 3-5 respectively, consistent with quasi-cylindrical conduit drawdown <2 km. The duration of vigorous explosion is given by the strain signature, indicating mass fluxes of order 10 7 kg s −1 . Conduit pressures released reflect static weight of porous gas-charged magma, and exsolution-generated overpressures of order 10 MPa.

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Section: Strain Analysis and Other Resultssupporting

confidence: 67%

Unique strainmeter observations of Vulcanian explosions, Soufrière Hills Volcano, Montserrat, July 2003

Voight

Hidayat

Sacks

et al. 2010

Geophysical Research Letters

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“…Even so, to test whether cooling (conductive heat transfer) played a dominant role for increasing magma viscosity, enabling the generation the syn-emplacement strain localization and banded fracturing in the Sandfell laccolith, we modeled the cooling of a magma body with similar dimensions to the Sandfell laccolith under plausible time scales of intrusion emplacement. As the feeder of the Sandfell laccolith is not exposed, we constrain time scales of intrusion by using average extrusion rates of observed intrusive and extrusive dome building eruptions (1-10 m 3 /s, Newhall and Melson, 1983;Sparks et al, 1998) and estimated effusion rates of Icelandic dike-fed rhyolitic eruptions (1-10 m 3 /s, Höskuldsson and Sparks, 1997;Tuffen and Castro, 2009). Notably, the Cordón Caulle laccolith that was related to an ongoing eruption had a mean intrusion rate of ∼300 m 3 /s (Castro et al, 2016).…”

Section: Syn-emplacement Fracturingmentioning

confidence: 99%

Syn-Emplacement Fracturing in the Sandfell Laccolith, Eastern Iceland—Implications for Rhyolite Intrusion Growth and Volcanic Hazards

et al. 2018

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Felsic magma commonly pools within shallow mushroom-shaped magmatic intrusions, so-called laccoliths or cryptodomes, which can cause both explosive eruptions and collapse of the volcanic edifice. Deformation during laccolith emplacement is primarily considered to occur in the host rock. However, shallowly emplaced laccoliths (cryptodomes) show extensive internal deformation. While deformation of magma in volcanic conduits is an important process for regulating eruptive behavior, the effects of magma deformation on intrusion emplacement remain largely unexplored. In this study, we investigate the emplacement of the 0.57 km 3 rhyolitic Sandfell laccolith, Iceland, which formed at a depth of 500 m in a single intrusive event. By combining field measurements, 3D modeling, anisotropy of magnetic susceptibility (AMS), microstructural analysis, and FEM modeling we examine deformation in the magma to constrain its influence on intrusion emplacement. Concentric flow bands and S-C fabrics reveal contact-parallel magma flow during the initial stages of laccolith inflation. The magma flow fabric is overprinted by strain-localization bands (SLBs) and more than one third of the volume of the Sandfell laccolith displays concentric intensely fractured layers. A dominantly oblate magmatic fabric in the fractured areas and conjugate geometry of SLBs, and fractures in the fracture layers demonstrate that the magma was deformed by intrusive stresses. This implies that a large volume of magma became viscously stalled and was unable to flow during intrusion. Fine-grained groundmass and vesicle-poor rock adjacent to the fracture layers point to that the interaction between the SLBs and the flow bands at sub-solidus state caused the brittle-failure and triggered decompression degassing and crystallization, which led to rapid viscosity increase in the magma. The extent of syn-emplacement fracturing in the Sandfell laccolith further shows that strain-induced degassing limited the amount of eruptible magma by essentially solidifying the rim of the magma body. Our observations indicate that syn-emplacement changes in rheology, and the associated fracturing of intruding magma not only occur in volcanic conduits, but also play a major role in the emplacement of viscous magma intrusions in the upper kilometer of the crust.

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“…Page | 17 monitored in unprecedented detail, with timing, volume and flow dynamic data all recorded for individual pyroclastic flows Barclay et al, 1998;Sparks et al, 1998Sparks et al, , 2000Young et al, 1998;Cole et al, 1998;Menlik and Sparks, 1999;Voight et al 1999;Couch et al, 2001Couch et al, , 2003Zellmer et al, 2003;Herd et al, 2005). In addition, the combined study of subaerial flow conditions into the ocean with in-situ deposit morphology derived from marine sediment cores during the current eruption has provided valuable insights into submarine pyroclastic flow emplacement dynamics (Trofimovs et al, 2006(Trofimovs et al, , 2008(Trofimovs et al, , 2013Le Friant et al, 2009.…”

Section: Montserrat: the Natural Laboratorymentioning

confidence: 99%

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

Cassidy

Watt

Palmer

et al. 2014

Earth-Science Reviews

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Detailed knowledge of the past history of an active volcano is crucial for the prediction of the timing, frequency and style of future eruptions, and for the identification of potentially at-risk areas. Subaerial volcanic stratigraphies are often incomplete, due to a lack of exposure, or burial and erosion from subsequent eruptions. However, many volcanic eruptions produce widelydispersed explosive products that are frequently deposited as tephra layers in the sea. Cores of marine sediment therefore have the potential to provide more complete volcanic stratigraphies, at least for explosive eruptions. Nevertheless, problems such as bioturbation and dispersal by currents affect the preservation and subsequent detection of marine tephra deposits.Consequently, cryptotephras, in which tephra grains are not sufficiently concentrated to form layers that are visible to the naked eye, may be the only record of many explosive eruptions.Additionally, thin, reworked deposits of volcanic clasts transported by floods and landslides, or during pyroclastic density currents may be incorrectly interpreted as tephra fallout layers, leading to the construction of inaccurate records of volcanism. This work uses samples from the volcanic island of Montserrat as a case study to test different techniques for generating volcanic eruption records from marine sediment cores, with a particular relevance to cores sampled in relatively proximal settings (i.e. tens of kilometres from the volcanic source) where volcaniclastic material may form a pervasive component of the sedimentary sequence. Visible volcaniclastic deposits identified by sedimentological logging were used to test the effectiveness of potential alternative volcaniclastic-deposit detection techniques, including point counting of grain types (component analysis), glass or mineral chemistry, colour spectrophotometry, grain size measurements, XRF core scanning, magnetic susceptibility and X-radiography. This study demonstrates that a set of time-efficient, non-destructive and high-spatial-resolution analyses (e.g. XRF core-scanning and magnetic susceptibility) can be used effectively to detect potential cryptotephra horizons in marine sediment cores. Once these horizons have been sampled, microscope image analysis of volcaniclastic grains can be used successfully to discriminate between tephra fallout deposits and other volcaniclastic deposits, by using specific criteria Page | 3 related to clast morphology and sorting. Standard practice should be employed when analysing marine sediment cores to accurately identify both visible tephra and cryptotephra deposits, and to distinguish fallout deposits from other volcaniclastic deposits.

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Magma production and growth of the lava dome of the Soufriere Hills Volcano, Montserrat, West Indies: November 1995 to December 1997

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Cited by 152 publications

References 10 publications

Unique strainmeter observations of Vulcanian explosions, Soufrière Hills Volcano, Montserrat, July 2003

Unique strainmeter observations of Vulcanian explosions, Soufrière Hills Volcano, Montserrat, July 2003

Syn-Emplacement Fracturing in the Sandfell Laccolith, Eastern Iceland—Implications for Rhyolite Intrusion Growth and Volcanic Hazards

Construction of volcanic records from marine sediment cores: A review and case study (Montserrat, West Indies)

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