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Volcanic debris avalanche propagation mechanisms and dynamics: The importance of lithological properties

Symeon Makris 1, Matteo Roverato2, Pablo Dávila Harris3, Alejandro Lomoschitz4, Paul Cole5, Irene Manzella6

  • Affiliations:  1 British Geological Survey (BGS), Edinburgh, UK; 2 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Alma Mater Studiorum, Università di Bologna, Italy; 3 División de Geociencias Aplicadas, IPICYT, San Luis Potosí, Mexico; 4 Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, ULPGC, 35017, Las Palmas de Gran Canaria, Spain; 5 School of Geography, Earth and Environmental Science, University of Plymouth, Plymouth, UK; 6 Department of Applied Earth Sciences (AES), Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede, The Netherlands 

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 183

  • Programme No: 3.5.42

  • Theme 3 > Session 5

Abstract

Volcanic debris avalanches (VDAs) pose significant hazards due to their long runouts and destructive potential. However, the mechanisms underlying their extreme mobility remain poorly constrained, as theoretical models struggle to interpret field observations, and numerical models rely on empirical parameters to reflect their low apparent friction. This study integrates field investigations and analogue experiments to explore VDA propagation mechanisms and dynamics. Two deposits in the Canary Islands are analyzed: Tenteniguada (Gran Canaria) and Abona (Tenerife), exhibiting distinct facies and sedimentological characteristics. Additionally, the Campo di Giove rock avalanche (Italy) is also used for comparison. Structure-from-motion photogrammetry was employed to generate 3D models of outcrops and sample windows, quantifying sedimentological properties. Conceptual models of propagation dynamics were developed based on these data. Tenteniguada is dominated by competent lava lithologies, with limited disaggregation and preservation of its original structure despite brittle deformation. Its propagation involved normal fault-accommodated spreading. This is similar to Campo di Giove, dominated by limestone. In contrast, Abona comprises predominantly weak pyroclastic materials, exhibiting extensive disaggregation and microfracturing. These characteristics facilitated spreading with distributed shear. The differences in propagation dynamics are attributed to contrasting material properties and stress distribution. The Abona study supports the hypothesis that VDAs can behave as granular flows, where particle interactions govern energy dissipation and momentum transfer. Auxiliary friction-reducing mechanisms are not essential for VDA mobility. Instead, increasing momentum and kinetic energy derived from initial potential energy can drive the flow. However, other mechanisms can also enable long runouts according to material properties.