Abstract
The Colca Valley in the Central Andes is a region characterized by the occurrence of large slow-moving landslides and a high level of seismic activity. In this study, we aimed to determine passive and active tectonic control on the formation of selected five large landslides in the Colca Valley and to assess geohazard associated with these features. For that purpose, we performed a post-landslide field survey, applied remote sensing techniques, and obtained eyewitness accounts. Recently, the need to understand mass movement processes in this region is even higher due to the establishment of the Colca y Volcanes de Andagua Geopark (Colca and Andagua Volcanoes Geopark). Our results suggest that the studied landslides usually represent a complex failure mechanism, dominated by translational sliding or rotational displacements, commonly associated with the formation of horst-and-graben like structures. We found a spatial correlation between the distribution of landslides and inherited fault network. The head scarps appear to be limited by the WNW- to NW-striking faults, whereas the lateral extent of some of the reported features seems to be connected with the NNE-striking normal faults, common in both, the Mesozoic strata and the Pleistocene-Holocene deposits.
Highlights
Landslides are one of the most dangerous geohazards, resulting in human death, economic loss, and environmental impact
Whereas the head scarps appear to be limited by the WNW- to NW-striking faults, the lateral extent of some of the reported features seems to be connected with the NNE-striking normal faults, common in both, the Mesozoic strata and the Pleistocene-Holocene deposits (Figure 3a)
A similar situation is observed in landslide B, i.e. the lateral extent of this feature coincides with the NNE-striking faults and corresponding lineaments (Figure 5), whereas the head scarp follows the trace of the NW-striking fault (Figure 5) that links with the active fault presented on a neotectonic map (Benavente et al 2017)
Summary
Landslides are one of the most dangerous geohazards, resulting in human death, economic loss, and environmental impact. 400 fatal landslides worldwide result in more than 4,500 fatalities (Petley 2012). Landslides encompass a wide variety of types and sizes, usually divided into five main groups of movement: falls, topples, slides, spreads, and flows (Hungr et al 2014). Major natural triggering mechanisms include water, seismic activity, and volcanic activity. Their effects vary widely and depend on internal factors such as lithology, tectonic structures, soil type, vegetation, and the occurrence of earlier landslides, as well as topographic characteristics such as morphology, slope steepness, slope aspect, slope profile, solar radiation, etc. Tectonic processes produce lines of weakness and failure surfaces (passive role) affecting the slopes, as well as the topographic growth and over-steepening of the slopes (active role) that promote the occurrence of large landslides (Carlini et al 2016)
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