Presentation and analysis of a worldwide database for lava dome collapse events: the Global Archive of Dome Instabilities (GLADIS)

Claire E Harnett,Alison Telford,William Murphy,Susanna K Ebmeier,Mark E Thomas,Jurgen Neuberg,Eliza S Calder

doi:10.1007/s00445-019-1276-y

Claire E Harnett, Alison Telford + Show 5 more

Open Access

https://doi.org/10.1007/s00445-019-1276-y

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Abstract

Lava dome collapses generate hazardous pyroclastic flows, rockfalls and debris avalanches. Despite advances in understanding lava dome collapses and their resultant products, the conditions that occur prior to collapse are still poorly understood. Here, we introduce the Global Archive of Dome Instabilities (GLADIS), a database that compiles worldwide historical dome collapses and their reported properties, including original dome volume (at the time of collapse), dome morphology, emplacement conditions, precursory activity, dome geometry and deposit characteristics. We determine the collapse magnitude for events where possible, using both absolute deposit volumes and relative collapse volume ratios (this being deposit volume as a proportion of original dome volume). We use statistical analysis to explore whether relationships exist between collapse magnitude and extrusion rate, dome growth style, original dome volume and causal mechanism of collapse. We find that relative collapse magnitude is independent of both the extrusion rate and the original dome volume. Relative collapse volume ratio is dependent on dome growth style, where endogenous growth is found to precede the largest collapses (~ 75% original volume). Collapses that comprise a higher proportion (> 50%) of original dome volume are particularly attributed to both gravitational loading and the development of gas overpressure, whilst collapses comprising a small proportion (< 10%) of original dome volume are associated with the topography surrounding the dome, and variations in extrusion direction. By providing validation and/or source data, we intend these data on various dome growth and collapse events, and their associated mechanisms, to be the focus of future numerical modelling efforts, whilst the identified relationships with relative collapse volume ratios can inform collapse hazard assessment based on observations of a growing dome.

Highlights

Lava domes and spines form when viscous magma is extruded but is not able to flow far from the volcanic vent (Calder et al 2015)
Page 9 of 17 16 available for 27% of events in the database (n = 78), and we focus on these events in the majority of our analysis as the collapse magnitude is one of the parameters that would be most useful to forecast for the purpose of hazard assessment
We suggest that for this type of study looking at forecasting dome collapse, the most important observations to be recorded during dome-forming eruptions that would aid further global statistical analysis are (a) original dome volume; (b) collapse volume; (c) dome growth style and (d) cause of collapse

Summary

Introduction

Lava domes and spines form when viscous magma is extruded but is not able to flow far from the volcanic vent (Calder et al 2015). Instability of lava domes results in pyroclastic flows, Editorial responsibility: J. Despite the threat posed by dome collapse, we still know relatively little about the interplay between dome growth conditions and the collapse mechanisms of lava domes. A broad variety of mechanisms, and triggers, have already been identified for individual collapse events. These include gravitational collapse (Ui et al 1999), rainfall (Matthews et al 2002) and gas overpressure (Voight and Elsworth 2000). The general conditions that determine which collapse mechanism is dominant are still not clear

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