Zonación de peligros por procesos gravitacionalesen el flanco suroccidental del volcán Pico de Orizaba, México

The study area is the river Chiquito-Barranca del Muerto watershed that covers 111 km2 and lies on the southwestern flank of Pico de Orizaba volcano. The water-shed was studied by using aerial photographs of different years and fieldwork with an adaptation of the Landslide Hazard Zonation Protocol of the Washington State Department of Natural Resources, usa. 571 gravitational processes of six types were recognized: shallow, debrisavalanche and deep, debris flows and erthflows, and rock falls. We defined 12 major landforms on which gravitational processes occur: inner gorges, headwalls, active scarps of deep-seated landslides, meanders, plains, three types of hillslopes classified by its gradient: low, moderate, and high, rockfall slopes, non-rule-identified inner gorges, non-rule-identified headwalls, and non-rule-identified converging hillslopes. The potential gravitational processes were classified into three hazard ranges: low, high, and very high. Gravitational processes occur primarily in moderate gradient hillslopes, non-rule-identified inner gorges, inner gorges, and low-gradient hillslopes. The stability is low for plains and low gradient hillslopes, high for moderate and steep gradient hillslopes, and very high for the remaining eight landforms.