Abstract:

Large landslides of different types not previously recorded are located in the left bank of the Río Curri Leuvú valley, north of the Tricao Malal village. There are situated among the Cerro Palao and the Palao pond and Riscos Negros site to the north. The largest landslides (Malal Cura and Arroyo Mogolillo landslides) correspond to the multiple rotational progressive type. They are developed on Mesozoic sedimentary rocks, covered by Cenozoic basalt flows. The debris and earth flows are developed in areas covered by the volcanic rocks of the Charilehue Formation (Middle Miocene) and continue north of study reaching the latitudes of the Grande and Medio streams and also the Colimamil stream valley southeast of Cerro Domuyo. The impact of these phenomena in the fluvial system was important and produced ephemeral and permanent blocking as seen in the La Turbia stream with coeval ponding. It is hypothesized that the landslide occurrence is related to excess or long-lasting periods of rain in postglacial times. It is also indicated the presence of rock glaciers in the Cerro Palao.