Evaluación de peligrosidad por procesos de remoción en masa en los cerros La Unión y Zaror.

Comuna de Talcahuano, Región del Biobío (Chile).

Abstract

On the hills La Union and Zaror the landslide hazard level is conditioned by a lithology of metamorphic rock in advanced state of weathering and a morphometry with slopes over 20º (Alarcón, 1995), in a highly saturated soil by intensities rainy periods above 50 mm of water daily drop in a maximum of 72 hours (Mardones et al., 1994). The results indicated that rotational landslides were the more predominant processes, which registered 21 active processes which showed higher activity in the winter months. The most number of MWP (Mass Wasting Processes) was concentrated on slopes between 6º and 27º on exposition N - NE - NW, which favored the appearance of shrub vegetation, that increased the levels of humidity and weathering on a soil of texture silt - clay, poorly cohesive and of easy mobilization by action of water and gravity, where with a threshold of 12.1 mm of water precipitated in 12 hours, the probability of triggering a landslide is very high because of high saturation of the soil. The result of the landslide hazard assessment allowed through the zonification of the most instable areas suggest the basis towards to territorial planning to reduce the vulnerability and encourage the rational land-use, providing to the local community the ability to adapt and face a natural hazard.