Bull Volcanol (2005) 67:441–456 DOI 10.1007/s00445-004-0386-2

RESEARCH ARTICLE

C. Bonadonna · B. F. Houghton

Total grain-size distribution and volume of tephra-fall deposits

Received: 27 January 2004 / Accepted: 19 August 2004 / Published online: 26 January 2005 ! Springer-Verlag 2005

Abstract On 17 June 1996, Ruapehu volcano, New Zealand, produced a sustained andesitic sub-Plinian eruption, which generated a narrow tephra-fall deposit extending more than 200 km from the volcano. The extremely detailed data set from this eruption allowed methods for the determination of total grain-size distribution and volume of tephra-fall deposits to be critically investigated. Calculated total grain-size distributions of tephra-fall deposits depend strongly on the method used and on the availability of data across the entire dispersal area. The Voronoi Tessellation method was tested for the Ruapehu deposit and gave the best results when applied to a data set extending out to isomass values of