A Reverse Dynamical Investigation of the Catastrophic Wood-Snow Avalanche of 18 January 2017 at Rigopiano, Gran Sasso National Park, Italy

Abstract

On 18 January 2017 a catastrophic avalanche destroyed the Rigopiano Gran Sasso Resort & Wellness (Rigopiano Hotel) in the Gran Sasso National Park in Italy, with 40 people trapped and a death toll of 29. This article describes the location of the disaster and the general meteorological scenario, with field investigations to provide insight on the avalanche dynamics and its interaction with the hotel buildings. The data gathered in situ suggest that the avalanche was a fluidized dry snow avalanche, which entrained a sligthtly warmer snow cover along the path and reached extremely long runout distances with braking effect from mountain forests. The avalanche that reached the Rigopiano area was a “wood-snow” avalanche—a mixture of snow and uprooted and crushed trees, rocks, and other debris. There were no direct eyewitnesses at the event, and a quick post-event survey used a numerical model to analyze the dynamics of the event to estimate the pressure, velocity, and direction of the natural flow and the causes for the destruction of the hotel. Considering the magnitude and the damage caused by the event, the avalanche was at a high to very high intensity scale.

Keywords

Avalanche flow velocity / Avalanche impact pressure / Forensic field investigation / Italy / Rigopiano disaster / Wood-snow avalanche

References

[1] Barbolini, M., L. Natale, G. Tecilla, and M. Cordola. 2005. Methodological guidelines for the perimetration of areas exposed to avalanche danger (Linee guida metodologiche per la perimetrazione delle aree esposte al pericolo di valanghe). AINEVA e Dipartimento di Ingegneria idraulica ed ambientale dell’Università degli Studi di Pavia. Technical report. https://docplayer.it/7174673-Linee-guida-metodologiche-per-la-perimetrazione-delle-aree-esposte-al-pericolo-di-valanghe.html. Accessed 23 Sept 2020 (in Italian).

[2] Barbolini, M. 2007. Definition of the project values for standard snow parameters to prevent avalanche risk in Aosta Valley (Definizione dei valori di progetto di parametri nivometrici standard per la prevenzione del rischio valanghivo sul territorio valdostano). Regione Autonoma Valle d’Aosta (updated August 2013). Technical report. https://www.regione.vda.it/territorio/territorio/parametrinivometrici/pages/Informazioni.htm. Accessed 23 Sept 2020 (in Italian).

[3] Bartelt P, Buser O, Vera Valero C, Bühler Y. Configurational energy and the formation of mixed flowing powder snow ice avalanches. Annals of Glaciology, 2016, 57(71): 179-187

[4] Bartelt, P., M. Christen, Y. Bühler, A. Caviezel, and O. Buser. 2018. Snow entrainment: Avalanche interaction with an erodible substrate. In Proceedings of the International Snow Science Workshop 2018, 7–12 October 2018, Innsbruck, Austria, 716–720.

[5] Berthet-Rambaud P, Limam A, Roenelle P, Rapin F, Tacnet J-M, Mazars J. Avalanche action on rigid structures: back-analysis of Taconnaz deflective walls’ collapse in February 1999. Cold Regions Science and Technology, 2007, 47(1–2): 16-31

[6] Brang P, Schönenberger W, Frehner M, Schwitter R, Thormann JJ, Wasser B. Management of protection forests in the European Alps—an overview. Forest Snow and Landscape Research, 2006, 80(1): 23-44.

[7] Brugnara, Y., S. Brönnimann, M. Zamuriano, J. Schild, C. Rohr, and D.M. Segesser. 2017. Reanalysis sheds light on 1916 avalanche disaster. ECMWF Newsletter, No. 151, April 2017. https://www.ecmwf.int/en/newsletter/151/meteorology/reanalysis-sheds-light-1916-avalanche-disaster. Accessed 20 Sept 2020.

[8] Chiaia B, Frigo B, Chiambretti I, Marello S, Maggioni M. Augenti N, Bontempi F. The Rigopiano avalanche: Dynamic analysis (La valanga di Rigopiano: l’analisi dinamica). Forensic engineering, collapses, structural reliability and consolidation (Ingegneria Forense, Crolli, Affidabilità strutturale e Consolidamento), 2017, Palermo: Tipografia Priulla 457-468 (in Italian)

[9] Chiambretti, I., and S. Sofia. 2018. Winter 2016–2017 snowfall and avalanche emergency management in Italy (Central Apennines)—a review. In Proceedings of the International Snow Science Workshop 2018, 7–12 October 2018, Innsbruck, Austria, 1445–1449.

[10] Chiambretti, I., B. Chiaia, B. Frigo, S. Marello, M. Maggioni, R. Fantucci, and M. Bernabei. 2018. The 18^th January 2017 Rigopiano avalanche disaster in Italy—Analysis of the applied forensic field investigation techniques. In Proceedings of the International Snow Science Workshop 2018, 7–12 October 2018, Innsbruck, Austria, 1208–1212.

[11] Christen M, Kowalski J, Bartelt P. RAMMS: numerical simulation of dense snow avalanches in three-dimensional terrain. Cold Regions Science and Technology, 2010, 63(1–2): 1-14

[12] De Quervain, M. 1978. Forest and avalanches (Wald und Lawinen). In Proceedings of the IUFRO Seminar Mountain Forests and Avalanches, 25–28 September 1978, Davos, Switzerland, 219–231 (in German).

[13] Feistl T, Bebi P, Teich M, Bühler Y, Christen M, Thuro K, Bartelt P. Observations and modeling of the braking effect of forests on small and medium avalanches. Journal of Glaciology, 2014, 60(219): 124-138

[14] Feistl T, Bebi P, Christen M, Margreth S, Diefenbach L, Bartelt P. Forest damage and avalanche flow regime. Natural Hazards and Earth System Sciences, 2015, 15(6): 1275-1288

[15] Fierz, C., R.L. Armstrong, Y. Durand, P. Etchevers, E. Greene, D.M. McClung, K. Nishimura, P.K. Satyawali, and S.A. Sokratov. 2009. The international classification for seasonal snow on the ground. IHP-VII technical documents in hydrology N°83, IACS contribution N°1. Paris: UNESCO-IHP.

[16] Frigo, B., B. Chiaia, I. Chiambretti, P. Bartelt, M. Maggioni, and M. Freppaz. 2018. The January 18^th 2017 Rigopiano avalanche disaster in Italy—Analysis of the avalanche dynamics. In Proceedings of the International Snow Science Workshop 2018, 7–12 October 2018, Innsbruck, Austria, 6–10.

[17] Gray DM, Male DH. Handbook of snow: Principle, process, management and use, 1981, Caldwell, NJ: The Blackburn Press

[18] Höller P. Avalanche cycles in Austria: an analysis of the major events in the last 50 years. Natural Hazards, 2009, 48(3): 399-424

[19] Maggioni M, Gruber U. The influence of topographic parameters on avalanche release dimension and frequency. Cold Regions Science and Technology, 2003, 37(3): 407-419

[20] McClung D, Schaerer P. The avalanche handbook, 1996, Seattle, WA: Mountaineers Books

[21] Meteomont Service. 2017. Avalanche Bulletin. Historical archive. http://www.meteomont.gov.it/infoMeteo/. Accessed 23 Sept 2020 (in Italian).

[22] Rapin, F. 2002. A new scale for avalanche intensity In Proceedings of the International Snow Science Workshop 2002, 29 September–4 October 2002, Penticton, B.C., Canada, 90–96.

[23] Rapin, F., and C. Ancey. 2000. Occurrence conditions of two catastrophic avalanches at Chamonix, France. In Proceedings of the International Snow Science Workshop 2000, 2–6 October 2000, Big Sky, Montana, USA, 509–513.

[24] Schweizer J, Jamieson B, Schneebeli M. Snow avalanche formation. Reviews of Geophysics, 2003, 41(4): 1016-1041

[25] SLF (Institut für Schnee- und Lawinenforschung). 1999. New calculation methods in the mapping of avalanche risks (Neue Berechnungsmethoden in der Lawinengefahrenkartierung). Technical report. Davos, Switzerland: Institut für Schnee- und Lawinenforschung (in German).

[26] Teich M, Fischer JT, Feistl T, Bebi P, Christen M, Grêt-Regamey A. Computational snow avalanche simulation in forested terrain. Natural Hazards and Earth System Sciences, 2014, 14(5): 2233-2248

[27] Vera Valero C, Jones KW, Bühler Y, Bartelt P. Release temperature, snow-cover entrainment and the thermal flow regime of snow avalanches. Cold Regions Science and Technology, 2015, 61(225): 173-184.

[28] Vera Valero C, Wever N, Christen M, Bartelt P. Modeling the influence of snow cover temperature and water content on wet-snow avalanche runout. Natural Hazards and Earth System Sciences, 2018, 18(3): 869-887