Keywords
wind direction
Tungurahua
isomass maps
tephra
physical volcanology
How to Cite
Abstract
The quantification of tephra fallouts can be affected by different parameters such as the quality of the deposit exposure and the calculation method. In this paper the effect of variability in the wind direction is investigated through the analysis of two eruptions from the Tungurahua volcano in Ecuador. The fluctuation in the wind direction was assessed using the alerts generated by the Washington VAAC (Volcanic Ash Advisory Center) and the actual fallout reports from local volunteers. Area densities (mass/area) of the tephra deposits were compiled by each co-author to create isomass maps. Empirical methods were used to calculate the total mass of the tephra fallouts. With this approach we were able to study the influence of the wind direction variability on the quantification of tephra fallouts under similar eruptive and sampling conditions. Our results indicate that, due to higher wind direction variability, the December 2012 eruption produced a non-elliptical complex deposit with a larger uncertainty on the calculated total mass value. The March 2013 eruption, on the other hand, occurred during a period of steady wind direction and left an almost elliptical deposit. The compilation of the data from the March eruption done by the co-authors demonstrates greater coherence and a less uncertainty in the final result. This study highlights that the choice of the empirical law to describe the fallout distribution must be adapted according to the map of the deposit.
References
Newhall, C.; Self, S. 1982. "The volcanic explosivity index (VEI): an estimate of explosive magnitude for historical volcanism". Journal of Geophysical Research, 87: 1231-1238.
Suzuki, T. 1983. "A theoretical model for dispersion of tephra". in: D. Shimozuru and I. Yokoyama (eds) Arc Volcanism: Physics and Tectonics, Terra Scientific Publishing, Tokyo, 95-116.
Pyle, M. 1983. "The thickness, volume and grainsize of tephra fall deposits". Bulletin ofVolcanology, 51: 1-15.
Fierstein, J.; Nathenson, M. 1992. "Another look at the calculation of fallout tephra volumes". Bulletin of Volcanology, 54: 156-167.
Bonadonna, C.; Ernst, G.; Sparks, R. 1998. "Thickness variations and volume estimates of tephra fall deposits: the importance of particle Reynolds number". Journal ofVolcanology and Geothermal Research, 81: 173-187.
Bonadonna, C.; Houghton, B. 2005. "Total grain-size distribution and volume of tephra fall deposits". Bulletin of Volcanology, 67: 441-456.
Biass, S.; Bonadonna, C. 2011. "A quantitative uncertainty assessment of eruptive parameters derived from tephra deposits: The example of two large eruptions of Cotopaxi volcano, Ecuador". Bulletin of Volcanology, 73: 73-90.
Eychenne, J.; Le Pennec, J.; Troncoso, L.; Gouhier, M.; Nedelec, J. 2012. "Causes and consequences of bimodal grain-size distribution of tephra fall deposited during the August 2006 Tungurahua eruption (Ecuador)". Bulletin of Volcanology, 74: 187-205.
Le Pennec, J.; Ruiz, G.; Ramón, P.; Palacios, E.; Mothes, P.; Yepes, H. 2012. "Impact of tephra falls on the Andean communities: The influences of eruption size and weather conditions during the 1999-2001 activity of Tungurahua volcano, Ecuador". Journal of Volcanology and Geothermal Research, 217: 91-103.
Bustillos, J. 2010. "Transición del estilo eruptivo durante las erupciones andesíticas en sistema abierto: Contribución al estudio de los depósitos de ceniza del volcán Tungurahua". Master thesis, Nice Sophia Antipolis University, France, 48.
Bustillos, J.; Mothes, P. 2010. "Ash falls at Tungurahua volcano: implementation of systematic ash collection for quantifying accumulated volumes". Cities On Volcanoes 6 abstract volume, Tenerife, Canary Island, Spain. May 31 - June 4 2010, 2.7-0-07.
Bernard, B. 2013. "Homemade ashmeter: a low-cost, high-efficiency solution to improve tephra field-data collection for contemporary explosive eruptions". Journal of Applied Volcanology, 2: 1-9.
Bonadonna, C.; Costa, A. 2012. "Estimating the volume of tephra deposits: A new simple strategy". Geology, 40 (5): 415-418.
Bonadonna, C.; Costa, A. 2013. "Modeling of tephra sedimentation from volcanic plumes". in: Modeling Volcanic Processes: The Physics and Mathematics of Volcanism.CAMBRIDGE: Cambridge University Press, Editors: S.A. Fagents, T.K.P.Gregg, R.M.C. Lopes, in press, ISBN: 9780521895439.
Copyright notice
Authors who publish in the journal ACI Avances en Ciencias e Ingenierías accept the following terms:
- The authors will retain their copyright and guarantee the journal the right of first publication of their work, which will be simultaneously subject to the Creative Commons Attribution License that allows third parties to share the work provided that its author and its first publication in this journal is indicated.
- Authors may adopt other non-exclusive license agreements for the distribution of the published version of the work, thereby being able to publish it in a monographic volume or reproduce it in other ways, provided that the initial publication in this journal is indicated.
- Authors are permitted and advised to disseminate their work over the Internet:
- Before submission to the journal, authors can deposit the manuscript in pre-publication files/repositories (preprint servers/repositories), including arXiv, bioRxiv, figshare, PeerJ Preprints, SSRN, and others, which can produce interesting exchanges and increase citations of the published work (see The effect of open access).
- After submission, it is recommended that authors deposit their article in their institutional repository, personal website, or scientific social network (such as Zenodo, ResearchGate or edu).