MeMoVolc consensual document: a review of cross-disciplinary approaches to characterizing small explosive magmatic eruptions

Abstract

A workshop entitled “Tracking and understanding volcanic emissions through cross-disciplinary integration: a textural working group” was held at the Université Blaise Pascal (Clermont-Ferrand, France) on the 6–7 November 2012. This workshop was supported by the European Science Foundation (ESF). The main objective of the workshop was to establish an initial advisory group to begin to define measurements, methods, formats and standards to be applied in the integration of geophysical, physical and textural data collected during volcanic eruptions. This would homogenize procedures to be applied and integrated during both past and ongoing events. The workshop comprised a total of 35 scientists from six countries (France, Italy, Great Britain, Germany, Switzerland and Iceland). The four main aims were to discuss and define: standards, precision and measurement protocols for textural analysis; identification of textural, field deposit, chemistry and geophysical parameters that can best be measured and combined; the best delivery formats so that data can be shared between and easily used by different groups; and multi-disciplinary sampling and measurement routines currently used and measurement standards applied, by each community. The group agreed that community-wide, cross-disciplinary integration, centred on defining those measurements and formats that can be best combined, is an attainable and key global focus. Consequently, we prepared this paper to present our initial conclusions and recommendations, along with a review of the current state of the art in this field that supported our discussions

Conduit Dynamics in Transitional Rhyolitic Activity Recorded by Tuffisite Vein Textures from the 2008–2009 Chaitén Eruption

“…Uncertainties related to quantitative textural analysis include user subjectivity, together with sample variability and possible non-representativeness (see discussion in Gurioli et al, 2015). Grayscale thresholding around vesicles and clasts includes intrinsic errors related to threshold position and manual drawing, which are greatest (∼10%) for small vesicles and when lowerresolution images are used (e.g., 5 µm rather than 0.13 µm pixel size), and exacerbated by small-scale spatial heterogeneities (Baker et al, 2011).…”

“…The porosity was calculated from each fragment using the dense rock equivalent (DRE) measured with the Accupyc 1340 Helium Pycnometer on the same powdered samples ( Table 1). Description of the protocol for density and vesicle connectivity measurements is provided in Gurioli et al (2015), and in the Supplementary Datasheets 1 and 2. The major element composition of the glasses and the mineral phases was characterized using electron probe microanalysis with a CAMECA SX100 system at LMV, using spot sizes between 5 and 20 microns depending on local clast textures.…”

“…In this paper we present a textural study of a tuffisite vein within a rhyolitic obsidian bomb ejected during the transitional phase of the Chaitén 2008 eruption. Pyroclast textures are deeply related to the dynamic characteristics of eruptions and thus provide useful insights into eruptive processes (e.g., Shea et al, 2010;Giachetti et al, 2011;Rust and Cashman, 2011;Gurioli et al, 2015). Here we apply this approach to pyroclasts trapped within the vein, with the aim of quantifying the poorly-constrained fragmentation, decompression and vesiculation processes that accompany tuffisite vein formation.…”

Effusive crises at Piton de la Fournaise 2014–2015: a review of a multi-national response model

“…Vesicle and crystal contents, as well as their size distributions, are also derived from all pyroclasts and lava samples (see Gurioli et al (2015), Latutrie et al (2017) and Colombier et al (2017) for the detail regarding standard procedures, plus the meaning and application of the measurements). These measurements are performed to check variation in space (down a fissure or vent system) and in time, both within single eruptions and between different eruptions.…”

From magma ascent to ash generation: investigating volcanic conduit processes by integrating experiments, numerical modeling, and observations

“…A general point of discussion was the requirement to assess and present estimates of uncertainties and errors for measurements and observations, with a distinction between actual errors on a given measurement and those on inferred information, which have a larger uncertainty [e.g., Biass andBonadonna 2011, Engwell et al 2013]. Such distinction is of paramount importance, because errors and uncertainties feed through to estimates of other measurements and model results (for example, tephra volume, TGSDs, PDDs and dispersion modeling) [Burden et al 2011, Engwell et al 2015, see also discussion in Gurioli et al 2015].…”