A Neogene giant landslide in Tarapacá, northern Chile: A signal of instability of the westernmost Altiplano and palaeoseismicity effects |
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| Authors: | L Pinto G Hrail SA Sepúlveda P Krop |
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| Institution: | aDepartamento de Geología, Universidad de Chile, Casilla 13518, Correo 21, Santiago, Chile;bLMTG, IRD, CNRS, Université de Toulouse, OMP, 14 Avenue Edouard Belin, 31400, Toulouse, France;cEcole Nationale Supérieure de Géologie, Rue du Doyen Marcel Roubault, 54501 Vandoeuvre les Nancy Cedex, France |
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| Abstract: | Giant landslides, which usually have volumes up to several tens of km3, tend to be related to mountainous reliefs such as fault scarps or thrust fronts. The western flank of the Precordillera in southern Peru and northern Chile is characterized by the presence of such mega-landslides. A good example is the Latagualla Landslide (19°15′S), composed of ~ 5.4 km3 of Miocene ignimbritic rock blocks located next to the Moquella Flexure, a structure resulting from the propagation of a west-vergent thrust blind fault that borders the Precordillera of the Central Depression. The landslide mass is very well preserved, allowing reconstitution of its movement and evolution in three main stages. The geomorphology of the landslide indicates that it preceded the incision of the present-day valleys during the late Miocene. Given the local geomorphological conditions 8–9 Ma ago (morphology, slopes and probably a high water table), large-magnitude earthquakes could have provided destabilization forces enough to cause the landslide. On the other hand, present seismic forces would not be sufficient to trigger such landslides; therefore the hazard related to them in the region is low. |
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| Keywords: | Landslide Earthquake Palaeoseismicity Altiplano Hazard |
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