Tropical storm-induced landslide-dammed lakes and debris flow hazards at Ocotepeque, Western Honduras

摘要

One of the deadliest tropical storms on record in Central America is the 1934 tropical storm that resulted in over 3000 fatalities; the majority of fatalities caused by floods, debris flows, and landslides. The hardest hit region was in western Honduras near the city of Ocotepeque, where 64cm of rain fell on June 4, 1934. The rainfall caused a rock landslide forming a natural dam in a mountain valley above Ocotepeque. The dam failed 3days later on June 7. The ensuing debris flow destroyed Ocotepeque killing an estimated 486 people, over 10% of the city's population. There was little to no reporting of this disaster due to the city's remote location and lack of adequate communications. Following this event, the city was relocated 4km north of Ocotepeque and renamed Nueva Ocotepeque. Over time, however, the old location, Ocotepeque, was resettled and called Antigua Ocotepeque. In this study, we examine the 1934 event and the effects of a similar recurrence on both Antigua Ocotepeque and Nueva Ocotepeque. Landslide hazard maps of the area (for shallow landslides) were generated and used to investigate the possibility of landslide dams forming. The potential debris flow inundation areas were predicted, and the effects of potential debris flows were investigated. Deterministic slope stability analyses conducted on the new location indicated that potential landslides could be more significant than suggested by the current hazard maps.