Tectonic control on slow-moving Andean landslides in the Colca Valley, Peru

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.