Bulletin of Volcanology

, 75:680 | Cite as

Determination of the largest clast sizes of tephra deposits for the characterization of explosive eruptions: a study of the IAVCEI commission on tephra hazard modelling

  • Costanza BonadonnaEmail author
  • Raffaello Cioni
  • Marco Pistolesi
  • Chuck Connor
  • Simona Scollo
  • Laura Pioli
  • Mauro Rosi
Research Article


The distribution of clasts deposited around a volcano during an explosive eruption typically contoured by isopleth maps provides important insights into the associated plume height, wind speed and eruptive style. Nonetheless, a wide range of strategies exists to determine the largest clasts, which can lead to very different results with obvious implications for the characterization of eruptive behaviour of active volcanoes. The IAVCEI Commission on Tephra Hazard Modelling has carried out a dedicated exercise to assess the influence of various strategies on the determination of the largest clasts. Suggestions on the selection of sampling area, collection strategy, choice of clast typologies and clast characterization (i.e. axis measurement and averaging technique) are given, mostly based on a thorough investigation of two outcrops of a Plinian tephra deposit from Cotopaxi volcano (Ecuador) located at different distances from the vent. These include: (1) sampling on a flat paleotopography far from significant slopes to minimize remobilization effects; (2) sampling on specified-horizontal-area sections (with the statistically representative sampling area depending on the outcrop grain size and lithic content); (3) clast characterization based on the geometric mean of its three orthogonal axes with the approximation of the minimum ellipsoid (lithic fragments are better than pumice clasts when present); and (4) use of the method of the 50th percentile of a sample of 20 clasts as the best way to assess the largest clasts. It is also suggested that all data collected for the construction of isopleth maps be made available to the community through the use of a standardized data collection template, to assess the applicability of the new proposed strategy on a large number of deposits and to build a large dataset for the future development and refinement of dispersal models.


Volcanic ash Volcanic plumes Field strategies Tephra sedimentation Particle characterization 



All workshop participants are especially thanked for their enthusiastic contribution and hard work to collect and characterize a large number of clasts in only 1 day (A. Amigo, D. Andronico, B.L. Browne, K. Bull, R. Carey, K. Cashman, M. Coltelli, L. Connor, L. Costantini, P. Del Carlo, B. Houghton, S. Jenkins, M. Jutzeler, S. Kobs, P. Landi, N. Lautze, C. Magill, C. Melendez Christyanne, C. Principe, F.M. Salani, P. Sruoga, D. Swanson, S. Takarada, A. Volentik, H. Wright). In fact, most data processing to determine the maximum clast was done during the second day of the workshop and preliminary results were discussed with the whole group. Thorough reviews of the Associate Editor V. Manville, S. Sparks and M. Ort have significantly improved the manuscript.

Supplementary material

445_2012_680_MOESM1_ESM.xls (35 kb)
ESM 1 (XLS 35 kb)


  1. Aschenbrenner BC (1956) A new method of expressing particle sphericity. J Sediment Petrol 26(1):15–31Google Scholar
  2. Barberi F, Coltelli M, Frullani A, Rosi M, Almeida E (1995) Chronology and dispersal characteristics of recently (last 5000 years) erupted tephra of Cotopaxi (Ecuador): implications for long-term eruptive forecasting. J Volcanol Geotherm Res 69:217–239CrossRefGoogle Scholar
  3. Barnett V, Lewis T (1998) Outliers in statistical data. Wiely, Chichester, 584 ppGoogle Scholar
  4. 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. Bull Volcanol 73:73–90CrossRefGoogle Scholar
  5. Burden RE, Phillips JC, Hincks TK (2011) Estimating volcanic plume heights from depositional clast size. Journal of Geophysical Research-Solid Earth 116: B11206 doi: 10.1029/2011JB008548
  6. Carey SN, Sigurdsson H (1986) The 1982 eruptions of El chichon volcano, Mexico (2): observations and numerical modelling of tephra-fall distribution. Bull Volcanol 48:127–141CrossRefGoogle Scholar
  7. Carey S, Sigurdsson H (1987) Temporal variations in column height and magma discharge rate during the 79 AD eruption of Vesuvius. Geol Soc Am Bull 99(2):303–314CrossRefGoogle Scholar
  8. Carey SN, Sparks RSJ (1986) Quantitative models of the fallout and dispersal of tephra from volcanic eruption columns. Bull Volcanol 48:109–125CrossRefGoogle Scholar
  9. Chernick MR (1982) A note on the robustness of Dixon’s ratio test in small samples. Am Stat 36:140Google Scholar
  10. Coltelli M, Del Carlo P, Vezzoli L (1998) Discovery of a Plinian basaltic eruption of roman age at Etna volcano, Italy. Geology 26:1095–1098CrossRefGoogle Scholar
  11. Connor LJ, Connor CB (2006) Inversion is the key to dispersion: understanding eruption dynamics by inverting tephra fallout. In: Mader H, Cole S, Connor CB, Connor LG (eds) Statistics in volcanology. Geological Society, London, pp 231–242Google Scholar
  12. Delaney G, Weaire D, Hutzler S, Murphy S (2005) Random packing of elliptical disks. Philosophical Magazine Letters 85(2):89–96Google Scholar
  13. Di Muro A, Rosi M, Aguilera E, Barbieri R, Massa G, Mundula F, Pieri F (2008) Transport and sedimentation dynamics of transitional explosive eruption columns: the example of the 800 BP Quilotoa Plinian eruption (Ecuador). J Volcanol Geotherm Res 174:307–324CrossRefGoogle Scholar
  14. Dixon WJ (1950) Analysis of extreme values. Ann Math Stat 21:488–506CrossRefGoogle Scholar
  15. Gordon ND, McMahon TA, Finlayson BL (1992) Stream hydrology. An introduction for ecologists. John Wiley and Sons, Chichester, GBGoogle Scholar
  16. Mastin LG, Guffanti M, Servranckx R, Webley P, Barsotti S, Dean K, Durant A, Ewert JW, Neri A, Rose WI, Schneider D, Siebert L, Stunder B, Swanson G, Tupper A, Volentik A, Waythomas CF (2009) A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions. J Volcanol Geotherm Res 186:10–21CrossRefGoogle Scholar
  17. Papale P, Rosi M (1993) A case of no-wind plinian fallout at Pululagua caldera (Ecuador): implications for models of clast dispersal. Bull Volcanol 55:523–535CrossRefGoogle Scholar
  18. Pyle DM (1989) The thickness, volume and grainsize of tephra fall deposits. Bull Volcanol 51:1–15CrossRefGoogle Scholar
  19. Rosi M, Paladio-Melosantos M, Di Muro A, Leoni R, Bacolcol T (2001) Fall vs flow activity during the 1991 climactic eruption of Pinatubo volcano (Philippines). Bull Volcanol 62:549–566CrossRefGoogle Scholar
  20. Scollo S, Tarantola S, Bonadonna C, Coltelli M, Saltelli A (2008) Sensitivity analysis and uncertanity estimation for tephra dispersal models. J Geophys Res 113(B06202)Google Scholar
  21. Shaw DM, Watkins ND, Huang TC (1974) Atmospherically transported volcanic glass in deep sea sediments: theoretical considerations. J Geophys Res 79:3087–3094CrossRefGoogle Scholar
  22. Sparks RSJ (1986) The dimensions and dynamics of volcanic eruption columns. Bull Volcanol 48:3–15CrossRefGoogle Scholar
  23. Sparks RSJ, Wilson L, Sigurdsson H (1981) The pyroclastic deposits of the 1875 eruption of Askja, Iceland. Philosophical Transaction of the Royal Society of London 229:241–273Google Scholar
  24. Suzuki T, Katsu Y, Nakamura T (1973) Size distribution of the tarumai Ta-b pumice-fall deposit. Bulletin of the Volcanological Society of Japan 18:47–64Google Scholar
  25. Tukey JW (1977) Exploratory data analysis. Addison-Wesley, Reading, MAGoogle Scholar
  26. Turner JS (1979) Buoyancy effects in fluids. Cambridge University Press, Cambridge, p 368Google Scholar
  27. Walker GPL (1973) Explosive volcanic eruptions—a new classification scheme. Geol Rundsch 62:431–446CrossRefGoogle Scholar
  28. Walker GPL, Croasdale R (1971) Two plinian-type eruptions in the Azores. J Geol Soc Lond 127:17–55CrossRefGoogle Scholar
  29. Wilson L, Huang TC (1979) The influence of shape on the atmospheric settling velocity of volcanic ash particles. Earth and Planetary Sciences Letters 44:311–324CrossRefGoogle Scholar
  30. Wilson L, Walker GPL (1987) Explosive volcanic-eruptions.6. Ejecta dispersal in plinian eruptions—the control of eruption conditions and atmospheric properties. Geophys J R Astron Soc 89:657–679CrossRefGoogle Scholar
  31. Woods AW (1988) The fluid-dynamics and thermodynamics of eruption columns. Bull Volcanol 50:169–193CrossRefGoogle Scholar
  32. Yuzyk TR, Winkler T (1991) Procedures for bed-material sampling. Lesson package no. 28. Environment Canada, Water Resources Branch, Sediment Survey Section, OttawaGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Costanza Bonadonna
    • 1
    Email author
  • Raffaello Cioni
    • 2
  • Marco Pistolesi
    • 3
  • Chuck Connor
    • 4
  • Simona Scollo
    • 5
  • Laura Pioli
    • 1
  • Mauro Rosi
    • 3
  1. 1.Earth and Environmental Sciences SectionUniversity of GenevaGenevaSwitzerland
  2. 2.Dipartimento di Scienze Chimiche e GeologicheUniversita’ di CagliariCagliariItaly
  3. 3.Dipartimento di Scienze della TerraUniversita’ di PisaPisaItaly
  4. 4.Department of GeologyUniversity of South FloridaTampaUSA
  5. 5.Istituto Nazionale di Geofisica e Vulcanologia-sezione di CataniaCataniaItaly

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