Insights into processes and deposits of hazardous vulcanian explosions at Soufrière Hills Volcano during 2008 and 2009 (Montserrat, West Indies)

Komorowski, Jean‐Christophe; Legendre, Yoann; Christopher, T.; Bernstein, Marc; Stewart, R. C.; Joseph, E. P.; Fournier, N.; Chardot, Lauriane; Finizola, Anthony; Wadge, G.; Syers, Racquel; Williams, Carlisle; Bass, V.

doi:10.1029/2010gl042558

Cited by 43 publications

(47 citation statements)

References 20 publications

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“…We observed hydrous silicate minerals on erosional scarps of the dome complex, which would be consistent with water dissolving silica from dome rock and then cooling as it percolates out to the surface. The precipitation of siliceous sinter, in sufficient quantities, may have implications for dome stability and/or dome permeability (Boudon et al 1998;Komorowski et al 1997;Komorowski et al 2010). Based on our work, however, we cannot determine whether sinter at Santiaguito is sufficiently pervasive to have such effects.…”

Section: Discussioncontrasting

confidence: 45%

An assessment of hydrothermal alteration in the Santiaguito lava dome complex, Guatemala: implications for dome collapse hazards

et al. 2013

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A combination of field mapping, geochemistry, and remote sensing methods has been employed to determine the extent of hydrothermal alteration and assess the potential for failure at the Santiaguito lava dome complex, Guatemala. The 90-year-old complex of four lava domes has only experienced relatively small and infrequent dome collapses in the past, which were associated with lava extrusion. However, existing evidence of an active hydrothermal system coupled with intense seasonal precipitation also presents ideal conditions for instability related to weakened clay-rich edifice rocks. Mapping of the Santiaguito dome complex identified structural features related to dome growth dynamics, potential areas of weakness related to erosion, and locations of fumarole fields. X-ray diffraction and backscattered electron images taken with scanning electron microscopy of dacite and ash samples collected from around fumaroles revealed only minor clay films, and little evidence of alteration. Mineral mapping using ASTER and Hyperion satellite images, however, suggest low-temperature (<150°C) silicic alteration on erosional surfaces of the domes, but not the type of pervasive acid-sulfate alteration implicated in collapses of other altered edifices. To evaluate the possibility of internal alteration, we re-examined existing aqueous geochemical data from dome-fed hot springs. The data indicate significant water-rock interaction, but the Na-Mg-K geoindicator suggests only a short water residence time, and δ 18 O/δD ratios show only minor shifts from the meteoric water line with little precipitation of secondary (alteration) minerals. Based on available data, hydrothermal alteration on the dome complex appears to be restricted to surficial deposits of hydrous silica, but the study has highlighted, importantly, that the 1902 eruption crater headwall of Santa María does show more advanced argillic alteration. We also cannot rule out the possibility of advanced alteration within the dome complex interior that is not accessible to the methods used here. It may therefore be prudent to employ geophysical methods to make further assessments in the future.

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Section: Discussioncontrasting

confidence: 45%

An assessment of hydrothermal alteration in the Santiaguito lava dome complex, Guatemala: implications for dome collapse hazards

et al. 2013

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“…For the 25 June 1997 SHV BAF described in detail by Loughlin et al (2002b), detachment of ash-cloud surges was found to occur at valley bends and constrictions, and was related to the slope of the channel, and was enhanced by depositional filling. Cole et al (2002), analysing data collated from 14 SHV flows, found Komorowski et al (2010). .…”

Section: Previous Workmentioning

confidence: 99%

“…A number of field studies investigate the morphology and granulometry of single events in great detail (e.g. Loughlin et al 2002b;Charbonnier & Gertisser 2008;Komorowski et al 2010;Lube et al 2011;Komorowski et al 2013), but few aggregate many events in order to extract general information and investigate similarities and differences between PDCs. Complex field relationships that result from the spatial and temporal variability of PDCs need to be reliably distilled in order to understand key physical processes which apply generically and which can be incorporated into dense-dilute coupled models.…”

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confidence: 99%

Chapter 10 The effect of topography on ash-cloud surge generation and propagation

Ogburn

Calder

Cole

et al. 2014

Memoirs

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Abstract:The relationship between valley morphology and ash-cloud surge development for 12 pyroclastic density currents (PDCs) at Soufrière Hills Volcano (SHV), Montserrat is investigated. Channel slope, sinuosity and cross-sectional area were measured from highresolution digital elevation models (DEMs) using geographical information system (GIS) software; and were compared to geometric parameters of the deposits. The data illustrate three surge-generation regimes: a proximal area of rapid expansion; a medial deflation zone; and a steadier distal surge 'fringe'. The extent to which these regimes develop varies with flow volume. For larger flows, within the proximal and medial regimes, a strong inverse correlation exists between surge detachment and valley cross-sectional area. Surge detachment is also correlated with observed and modelled flow velocities. Areas of topography-induced increases in velocity are interpreted to result in more pervasive fragmentation and fluidization, and thus enhanced surge generation. Distally, surge deposits appear as fringes with decaying extents, indicative of more passive expansion and decreasing velocity. The results indicate that surge mobility and detachment are a complex product of flow mass flux and topography, and that future efforts to model dense-dilute coupled flows will need to account for and integrate several mechanisms acting on different parts of the flow.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.The development and subsequent decoupling of dilute, turbulent ash-cloud surges from dense basal pyroclastic flows is poorly understood, unpredictable and often results in deadly consequences. Ash-cloud surges can have a significant lateral component of motion, and have been known to detach and move independently from their parent flows (Fisher 1995). For example, decoupled pyroclastic surges were responsible for fatalities

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“…Pyroclastic density currents (PDCs) have deposited fine-grained, ash-and pumice-rich, and coarser-grained blocky deposits around the volcano (Cole et al, 2002;Stinton et al, 2014), supplemented by tephra deposits from short-lived Vulcanian explosions and associated fountain-collapse flows and surges (Komorowski et al, 2010). Prevailing winds often distribute ash from weak plumes to the west, but larger plumes can also deposit to the north, east and south (Bonadonna et al, 2002).…”

Section: Soufrière Hills Volcano Montserratmentioning

confidence: 99%

“…The andesitic dome-forming eruption of SHV began in July 1995 and has featured several phases of activity consisting of dome growth, dome collapse and Vulcanian explosions as well as pauses in magma extrusion (Bonadonna et al, 2002;Komorowski et al, 2010;Stinton et al, 2014). Pyroclastic density currents (PDCs) have deposited fine-grained, ash-and pumice-rich, and coarser-grained blocky deposits around the volcano (Cole et al, 2002;Stinton et al, 2014), supplemented by tephra deposits from short-lived Vulcanian explosions and associated fountain-collapse flows and surges (Komorowski et al, 2010).…”

Section: Soufrière Hills Volcano Montserratmentioning

confidence: 99%

Real-time prediction of rain-triggered lahars: incorporating seasonality and catchment recovery

Jones

Manville

Peakall

et al. 2017

Nat. Hazards Earth Syst. Sci.

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Abstract. Rain-triggered lahars are a significant secondary hydrological and geomorphic hazard at volcanoes where unconsolidated pyroclastic material produced by explosive eruptions is exposed to intense rainfall, often occurring for years to decades after the initial eruptive activity. Previous studies have shown that secondary lahar initiation is a function of rainfall parameters, source material characteristics and time since eruptive activity. In this study, probabilistic rain-triggered lahar forecasting models are developed using the lahar occurrence and rainfall record of the Belham River valley at the Soufrière Hills volcano (SHV), Montserrat, collected between April 2010 and April 2012. In addition to the use of peak rainfall intensity (PRI) as a base forecasting parameter, considerations for the effects of rainfall seasonality and catchment evolution upon the initiation of raintriggered lahars and the predictability of lahar generation are also incorporated into these models. Lahar probability increases with peak 1 h rainfall intensity throughout the 2-year dataset and is higher under given rainfall conditions in year 1 than year 2. The probability of lahars is also enhanced during the wet season, when large-scale synoptic weather systems (including tropical cyclones) are more common and antecedent rainfall and thus levels of deposit saturation are typically increased. The incorporation of antecedent conditions and catchment evolution into logistic-regression-based raintriggered lahar probability estimation models is shown to enhance model performance and displays the potential for successful real-time prediction of lahars, even in areas featuring strongly seasonal climates and temporal catchment recovery.

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Insights into processes and deposits of hazardous vulcanian explosions at Soufrière Hills Volcano during 2008 and 2009 (Montserrat, West Indies)

Cited by 43 publications

References 20 publications

An assessment of hydrothermal alteration in the Santiaguito lava dome complex, Guatemala: implications for dome collapse hazards

An assessment of hydrothermal alteration in the Santiaguito lava dome complex, Guatemala: implications for dome collapse hazards

Chapter 10 The effect of topography on ash-cloud surge generation and propagation

Real-time prediction of rain-triggered lahars: incorporating seasonality and catchment recovery

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