The occurrence of rockslides ad rock avalanches in Central Andes of Argentina and possible conditioning by permafrost degradation

CARLA TAPIA BALDIS; DARIO TROMBOTTO LIAUDAT

PERMAFROST AND PERIGLACIAL PROCESSES

JOHN WILEY & SONS LTD

Lugar: Londres; Año: 2019

1045-6740

An inventory of rockslides androck avalanches in the austral part of the Santa Cruz river basin (31°40? to31°50?S, 70°30? to 70°10?W), San Juan, Argentina was carried out. The studyarea comprises a surface of approximately 432 km2 (50% above 3500 masl). 15 rockslides, 12 complex rockslides evolving to rock avalanches and 19rock avalanches, were identified. The deposits were analysed with remotesensory imagery as well as with field recognitions. They were analysed in orderto investigate processes under permafrost degradation because of globalwarming. Rock sampling procedures and laboratory rock-resistivity testing werealso made. The characterization of the detachment scars and the deposits fortwo rockslides was performed. Two different mechanisms were identified. In arockslide the shallow active layer detachment was favoured by theshear-displacement along pre-existing joints, as a result of short-termclimatic warming periods. Another case, a long-term permafrost degradation inrockslide, favoured a deeper failure process. The studied landslides processesshould not be explained by degradation permafrost factor alone. Faults, thegeometric arrangement of their structural elements and seismic activity maycontribute to trigger these phenomena. It is expected that the magnitude andfrequency of rockslides hazards will increase during the 21st century.