Recent catastrophic debris flows in Chile: Geological hazard, climatic relationships and human response

Abstract

Debris flows are an important type of geological hazard in Chile, affecting cities, towns and rural areas throughout the country despite the variation in climate regimes. In this summary paper, recent debris flows in the cities of Antofagasta and Santiago, in northern and central Chile, and in a rural area near Lake Ranco in central-southern Chile in 1991, 1993 and 2004, respectively, are reviewed. Triggering factors for flow occurrence are identified and different approaches to debris flow hazard assessment and the effects of debris flows on people and the environment are discussed. Furthermore, the relationships between debris flow occurrence and climatic anomalies such as El Nino episodes are analysed. A clear pattern of debris flow generation associated with El Nino events is found for Antofagasta and Santiago. The risk related to debris flows in Chile is of increasing importance because of the continuous expansion of cities to hazardous areas such as alluvial fans. The results show that hazard assessment based on several factors is essential for the implementation of proper prevention and mitigation measures for future debris flow events in the country.