The role of intra-arc strike-slip fault systems on landslide generation at Curarrehue (Central Southern Chilean Andes)

Abstract

Climate change has increased extreme rainfall events in the Central Southern Andes, favouring slope instabilities and triggering landslides. However, other predisposing factors that control landslides in this region are still poorly constrained. We systematically study the link between landslides and active faults systems thought detailed mapping and classification, highligthing mainly rock avalanches. Our analysis was complemented with hand-specimen and optical microscope host rock description, clay classification via x-ray diffraction and fluorescence, and an exhaustive fault kinematics assessment to determine the controlling the strain in the zone. Our results show that 90.5% of the landslides are linked with active strike-slip faults, characterised by phyllosilicate-bearing hydrothermally altered host rock. In this regard, the presence of clay minerals in fault-slip planes contributes to the generation of landslides in mountain ranges. This phenomenon could be enhanced due the ability to clays induce pressure variations by swelling triggering by extreme rainfalls. This interaction between faults and landslides is important for geological hazard assessment and landslide monitoring as being a recurrent configuration in this section of the Central Southern Chilean Andes.