Impact of a rock avalanche on a moraine‐dammed proglacial lake: Laguna Safuna Alta, Cordillera Blanca, Peru

Abstract

Hubbard, Bryn; Heald, A.; Reynolds, J.; Quincey, D., (2005) 'Impact of a rock avalanche on a moraine-dammed proglacial lake: Laguna Safuna Alta, Cordillera Blanca, Peru', Earth Surface Processes and Landforms 30(10) pp.1251-1264 RAE2008Moraines that dam proglacial lakes pose an increasing hazard to communities in the Andes and other mountain ranges. The moraines are prone to failure through collapse, overtopping by lake waters or the effect of displacement waves resulting from ice and rock avalanches. Resulting floods have led to the loss of thousands of lives in the Cordillera Blanca mountains of Peru alone in the last 100 years. On 22 April 2002 a rock avalanche occurred immediately to the south-west of Laguna Safuna Alta, in the Cordillera Blanca. The geomorphic evidence for the nature, magnitude and consequences of this event was investigated in August 2002. Field mapping indicated that the avalanche deposited 8-20 ? 106 m3 of rock into the lake and onto the surface of the frontal region of Glaciar Pucajirca, which flows into the lake. Repeated bathymetric surveying indicated that 5 ? 106 m3 of this material was deposited directly into the lake. The immediate effect of this event was to create a displacement wave that gained in height as it travelled along the lake basin, overtopping the impounding moraine at the lake's northern end. To achieve overtopping, the maximum wave height must have been greater than 100 m. This, and subsequent seiche waves, caused extensive erosion of both the proximal and distal faces of the impounding terminal moraine. Further deep gullying of the distal face of this moraine resulted from the supply of pressurized water to the face via a relief overflow tunnel constructed in 1978. Two-dimensional, steady-state analysis of the stability of the post-avalanche moraine rampart indicates that its proximal face remains susceptible to major large-scale rotational failure.Peer reviewe

Morphological analysis and features of the landslide dams in the Cordillera Blanca, Peru

“…During the last two centuries, global climate change has led to glacial retreat (Thompson et al 2000;Vuille et al 2008;Schauwecker et al 2014), resulting in thinning and fracturing of glaciers, formation of moraine dammed lakes (Hubbard et al 2005;Vilímek et al 2005), and slope instability, often involving river channels with the obstruction of valleys. All these consequences induced a range of significant hazards on the territory, (Lliboutry et al 1977;Carey 2005;Vilímek et al 2005;Iturrizaga 2014).…”

“…Several landslide dam inventories have been collected in different parts of the world, such as in North America (O'Connor and Costa 1993), South America (Hermanns et al 2011), Europe (Casagli and Ermini 1999;Bonnard 2011;Tacconi Stefanelli et al 2015), Central Asia (Popov 1990;Hewitt 1998;Strom 2010;Korup et al 2010;Schneider et al 2013), China (Dong et al 2009;Fan et al 2012;Peng and Zhang 2012), and New Zealand (Korup 2004). Although some reports on single events in the Cordillera Blanca Mountain Range, Peru, have been researched (Lliboutry et al 1977;Zapata 2002;Carey 2005;Hubbard et al 2005), no landslide dams and related lakes archive or any extended study on these topics are available yet.…”

A multi-level strategy for anticipating future glacier lake formation and associated hazard potentials

“…-Glacier retreat often exposes morainic and unconsolidated material ) that, if situated in steep terrain, is prone to be the starting zone for landslides and debris flows Haeberli et al, 1991;Hubbard et al, 2005). …”

Reconstructing historic Glacial Lake Outburst Floods through numerical modelling and geomorphological assessment: Extreme events in the Himalaya

“…These characteristics are also typical of many glacier-lake systems in the South American Cordillera Blanca (Lliboutry et al, 1977;Hubbard et al, 2005). The initiation of moraine-dam failure has been described as the result of wave-overtopping in both regions (Lliboutry et al, 1977;Reynolds, 1992;Clague and Evans, 1994;Richardson and Reynolds, 2000), and the development of intra-morainal springs and seepage, which may serve as a precursor to pipe-initiated failure, has also been documented (Clague and Evans, 2000;Lliboutry et al, 1977), although direct observations of piping style moraine-dam failure are scarce.…”