Abstract
Abstract. As a contribution to the knowledge of historical rockslides, this research focuses on the historical reconstruction, field mapping, and simulation of the expansion, through numerical modelling, of the 30 September 1513 Monte Crenone rock avalanche. Earth observation in 2-D and 3-D, as well as direct in situ field mapping, allowed the detachment zone and the perimeter and volume of the accumulation to be determined. Thanks to the reconstruction of the post-event digital elevation model based on historical topographic maps and the numerical modelling with the RAMMS::DEBRISFLOW software, the dynamics and runout of the rock avalanche were calibrated and reconstructed. The reconstruction of the runout model allowed confirmation of the historical data concerning this event, particularly the damming of the valley floor and the lake formation up to an elevation of 390 m a.s.l., which generated an enormous flood by dam breaching on 20 May 1515, known as the “Buzza di Biasca”.
Highlights
Massive rockslides and rock avalanches are natural events with high destructive potential that can have a devastating impact on a territory’s economic and social fabric
Five main conclusions can be drawn from the observations and modelling of the Monte Crenone rock avalanche (MCRA) event: 1. Geological observations as well as the historical sources indicate a series of collapses from the Monte Crenone that began at least as early as the 13th century, leading to the main rock avalanche of 30 September 1513, with a reconstructed volume of about 85.5 hm3
The MCRA modelling thanks to the RAMMS::DEBRISFLOW module allowed for a precise reconstruction of the event and of the accumulation volume and geometry
Summary
Massive rockslides and rock avalanches are natural events with high destructive potential that can have a devastating impact on a territory’s economic and social fabric. Even if such phenomena are rare, they cannot be considered negligible as natural hazards (Hungr and Evans, 2004). The dynamics of a rockslide, in the presence of 105 or 106 m3 of displaced rock and rapid movements, can evolve into a flow (Varnes, 1978) In this context, the term flow refers to a motion of debris on steep slopes, liquefied because of the low cohesion, that may advance well beyond the foot of the slopes. In the review of Hungr et al (2001) of the classification of the landslides, the term rock avalanche is defined as an extremely rapid, massive, flow-like motion (semicoherent flowing mass) of fragmented rock from a large rockslide or rockfall, with a volume > 1 hm
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