Estimation of Volcanic Hazards from Tephra Fallout

Connor, Charles B.; Hill, Brittain E.; Winfrey, Brandi; Franklin, Nathan M.; Femina, P. C. La

doi:10.1061/(asce)1527-6988(2001)2:1(33)

Cited by 133 publications

(94 citation statements)

References 22 publications

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“…Furthermore, the possible fissure opening and vent migration that may have accompanied the Fontana Lapilli eruption means that a widely distributed fallout area must be considered when compiling a hazard assessment. In carrying out such assessments, constraints on plume height, eruption duration, dispersal area, vent location and erupted mass are critical elements in hazard assessment during Plinian eruptions (Connor et al 2001;Cioni et al 2003;Bonadonna 2006). …”

Section: Hazard Implicationsmentioning

confidence: 99%

New physical characterization of the Fontana Lapilli basaltic Plinian eruption, Nicaragua

et al. 2008

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The Fontana Lapilli deposit was erupted in the late Pleistocene from a vent, or multiple vents, located near Masaya volcano (Nicaragua) and is the product of one of the largest basaltic Plinian eruptions studied so far. This eruption evolved from an initial sequence of fluctuating fountain-like events and moderately explosive pulses to a sustained Plinian episode depositing fall beds of highly vesicular basaltic-andesite scoria (SiO 2 >53 wt%). Samples show unimodal grain size distribution and a moderate sorting that are uniform in time. The juvenile component predominates (>96 wt%) and consists of vesicular clasts with both sub-angular and fluidal, elongated shapes. We obtain a maximum plume height of 32 km and an associated mass eruption rate of 1.4 × 10 8 kg s −1 for the Plinian phase. Estimates of erupted volume are strongly sensitive to the technique used for the calculation and to the distribution of field data. Our best estimate for the erupted volume of the majority of the climactic Plinian phase is between 2.9 and 3.8 km 3 and was obtained by applying a power-law fitting technique with different integration limits. The estimated eruption duration varies between 4 and 6 h. Marine-core data confirm that the tephra thinning is better fitted by a power-law than by an exponential trend.

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Section: Hazard Implicationsmentioning

confidence: 99%

New physical characterization of the Fontana Lapilli basaltic Plinian eruption, Nicaragua

et al. 2008

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“…These models include analytical solutions, used widely for investigations of particle sedimentation and for hazard assessments (e.g., Armienti et al, 1988;Bonadonna et al, 2005a;Bursik et al, 1992a and b;Connor et al, 2001;Connor and Connor, 2006;Glaze and Self, 1991;Hurst and Turner, 1999;Koyaguchi and Ohno, 2001a;Macedonio et al, 2005;Suzuki, 1983), and numerical models for real-time forecast of plume evolution and sedimentation (e.g., Costa et al, 2006;Searcy et al 1998). Both types have been validated with field data and are now used regularly for both these purposes.…”

Section: Introductionmentioning

confidence: 99%

A review of volcanic ash aggregation

Brown

Bonadonna

Durant

2012

Physics and Chemistry of the Earth, Parts A/B/C

228

298

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. (2012) 'A review of volcanic ash aggregation.', Physics and chemistry of the earth, parts A/B/C., 45-46 . pp. 65-78. Further information on publisher's website:http://dx.doi.org/10.1016/j.pce. 2011.11.001 Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractMost volcanic ash particles with diameters < 63 µm settle from eruption clouds as particle aggregates that cumulatively have larger sizes, lower densities, and higher terminal fall velocities than individual constituent particles. Particle aggregation reduces the atmospheric residence time of fine ash, which results in a proportional increase in fine ash fallout within 10s km to 100s km from the volcano and a reduction in airborne fine ash mass concentrations 1000s km from the volcano. Aggregate characteristics vary with distance from the volcano: proximal aggregates are typically larger (up to cm size) with concentric structures, while distal aggregates are typically smaller (sub-millimetre size). Particles comprising ash aggregates are bound through hydro-bonds (liquid and ice water) and electrostatic forces, and the rate of particle aggregation correlates with cloud liquid water availability. Eruption source parameters (including initial particle size distribution, erupted mass, eruption column height, cloud water content and temperature) and the eruption plume temperature lapse rate, coupled with the environmental parameters, determines the type and spatiotemporal distribution of aggregates. Field studies, lab experiments and modelling investigations have already provided important insights on the process of particle aggregation. However, new integrated observations that combine remote sensing studies of 2 ash clouds with field measurement and sampling, and lab experiments are required to fill current gaps in knowledge surrounding the theory of ash aggregate formation. Abstract word count: 222

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“…Suzuki 1983;Woods 1988;Bonadonna et al 1998), are widely used to predict patterns of tephra deposition or to estimate eruption parameters from deposit measurements (e.g. Armienti et al 1988;Connor et al 2001;Costa et al 2006). To improve the predictive capability of tephra dispersal models, it is important to capture the full spectrum of processes that characterise tephra sedimentation.…”

Section: Introductionmentioning

confidence: 99%

An example of enhanced tephra deposition driven by topographically induced atmospheric turbulence

et al. 2015

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Spatial variations in the thickness and grain-size characteristics of tephra fall deposits imply that tephra depositional processes cannot be fully captured by models of single-particle sedimentation from the base of the eruption plume. Here, we document a secondary thickness maximum in a ∼9.75 ka tephra fall deposit from Chaitén volcano, Chile (Cha1 eruption). This secondary thickness maximum is notably coarser-grained than documented historical examples, being dominated by medium-grained ash, and an origin via particle aggregation is therefore unlikely. In the region of secondary thickening, we propose that high levels of atmospheric turbulence accelerated particles held within the mid-to lower-troposphere (0 to ∼6 km) towards the ground surface. We suggest that this enhancement in vertical atmospheric mixing was driven by the breaking of lee waves, generated by winds passing over elevated topography beneath the eruption plume. Lower atmospheric circulation patterns may exert a significant control on the dispersal and deposition of tephra from eruption plumes across all spatial scales, particularly in areas of complex topography.

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Estimation of Volcanic Hazards from Tephra Fallout

Cited by 133 publications

References 22 publications

New physical characterization of the Fontana Lapilli basaltic Plinian eruption, Nicaragua

New physical characterization of the Fontana Lapilli basaltic Plinian eruption, Nicaragua

A review of volcanic ash aggregation

An example of enhanced tephra deposition driven by topographically induced atmospheric turbulence

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