Improving landslide hazard and risk mapping in Guatemala using terrain aspect

Guatemala is in the path of numerous atmospheric hazards that trigger landslides by saturating mountain slopes with water reducing their safety factor. Available local studies of landslide characterization in Guatemala have indicated the importance of slope in hazard and risk mapping, but, for the most part, ignored another topographic index: aspect. However, many regional studies analyzing the effect of hurricanes on terrain show that Caribbean and Central American locations experience higher impact from hurricanes and storms on eastern, southeastern, southern and southwestern slopes. Since hazard and risk mapping focuses on infrastructure and settlements located on slopes with various orientations, this factor needs to be addressed. This study uses landslide data from three areas in Guatemala affected by hurricanes Stan (2005) and Mitch (1998). The results from the conducted spatial and statistical analyses show a high association of landslide prone slopes with aspect within the 76 to 260 range (i.e., eastern-southeastern-southern and southwestern slopes). We hypothesize that this is the result of the regional wind circulation pattern governing moisture distribution. Integrating aspect in landslide analysis may improve hazard and risk mapping in Guatemala and other Central American and Caribbean regions by taking into account the regional patterns of wind circulation and the dominant role of eastern-southeastern-southwestern slopes in landslide processes.