scholarly journals Numerical simulation of explosive volcanic eruptions from the conduit flow to global atmospheric scales

2009 ◽  
Vol 48 (4-5) ◽  
Author(s):  
C. Textor ◽  
H. Graf ◽  
A. Longo ◽  
A. Neri ◽  
T. E. Ongaro ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Volcanic Eruptions ◽  
Conduit Flow ◽  
Explosive Volcanic Eruptions

scholarly journals The fate of volcanic ash: premature or delayed sedimentation?

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Eduardo Rossi ◽  
Gholamhossein Bagheri ◽  
Frances Beckett ◽  
Costanza Bonadonna
Keyword(s):  
Residence Time ◽  
Volcanic Ash ◽  
Volcanic Eruptions ◽  
Theoretical Description ◽  
Particle Sedimentation ◽  
Weather Modeling ◽  
Explosive Volcanic Eruptions ◽  
Travel Distances ◽  
Ash Dispersal

AbstractA large amount of volcanic ash produced during explosive volcanic eruptions has been found to sediment as aggregates of various types that typically reduce the associated residence time in the atmosphere (i.e., premature sedimentation). Nonetheless, speculations exist in the literature that aggregation has the potential to also delay particle sedimentation (rafting effect) even though it has been considered unlikely so far. Here, we present the first theoretical description of rafting that demonstrates how delayed sedimentation may not only occur but is probably more common than previously thought. The fate of volcanic ash is here quantified for all kind of observed aggregates. As an application to the case study of the 2010 eruption of Eyjafjallajökull volcano (Iceland), we also show how rafting can theoretically increase the travel distances of particles between 138–710 μm. These findings have fundamental implications for hazard assessment of volcanic ash dispersal as well as for weather modeling.

scholarly journals Revisiting the statistical analysis of pyroclast density and porosity data

2015 ◽  
Vol 7 (1) ◽  
pp. 1077-1095 ◽  
Author(s):  
B. Bernard ◽  
U. Kueppers ◽  
H. Ortiz
Keyword(s):  
Grain Size ◽  
Volcanic Eruptions ◽  
Large Datasets ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Statistical Tools ◽  
Statistical Relevance ◽  
Volcanic Deposits ◽  
Working Groups ◽  
Explosive Volcanic Eruptions

Abstract. Explosive volcanic eruptions are commonly characterized based on a thorough analysis of the generated deposits. Amongst other characteristics in physical volcanology, density and porosity of juvenile clasts are some of the most frequently used characteristics to constrain eruptive dynamics. In this study, we evaluate the sensitivity of density and porosity data and introduce a weighting parameter to correct issues raised by the use of frequency analysis. Results of textural investigation can be biased by clast selection. Using statistical tools as presented here, the meaningfulness of a conclusion can be checked for any dataset easily. This is necessary to define whether or not a sample has met the requirements for statistical relevance, i.e. whether a dataset is large enough to allow for reproducible results. Graphical statistics are used to describe density and porosity distributions, similar to those used for grain-size analysis. This approach helps with the interpretation of volcanic deposits. To illustrate this methodology we chose two large datasets: (1) directed blast deposits of the 3640–3510 BC eruption of Chachimbiro volcano (Ecuador) and (2) block-and-ash-flow deposits of the 1990–1995 eruption of Unzen volcano (Japan). We propose add the use of this analysis for future investigations to check the objectivity of results achieved by different working groups and guarantee the meaningfulness of the interpretation.

Sign in / Sign up

Export Citation Format

Share Document