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Landslide Susceptibility Assessment for ST. Thomas, Jamaica.The parish of St Thomas in Jamaica is highly prone to slope failure and in the past this has resulted in extensive damage and in some cases loss of life. To reduce the effect from landslides, there was an urgent need to map and assess areas that may be prone to future failure. Aerial photographs coupled with geomorphological field mapping were used to inventory the landslides. The factors conditioning the slopes for failure were assessed and a weighting value assigned to them. The weighting was achieved by using the principle of Bayesian conditional probability. The weighted factors were combined in a Geographical Information System (GIS) to produce a landslide susceptibility model for the study area. The susceptibility model created is in general agreement with the distribution of landslides in the area. Comparison of the model with the existing landslides showed that 97% of the landslides fell within the high and very high susceptibility zones of the model. Comparison of the model with landslides that occurred during 2002, and that were not used in the construction of the model, shows that 83 of the 89 slides that occurred fell within the high and very high susceptibility zones. The landslide susceptibility model created hopefully will be one of the first steps in looking at the risks landslides pose to lives, developments, whether it is housing, agriculture or the physical infrastructure and may be used to guide land-use planning in the parish
Rainfall Thresholding and Susceptibility assessment of rainfall induced landslides: application to landslide management in St Thomas, JamaicaThe parish of St Thomas has one of the highest densities of landslides in Jamaica, which impacts the residents, local economy and the built and natural environment. These landslides result from a combination of steep slopes, faulting, heavy rainfall and the presence of highly weathered volcanics, sandstones, limestones and sandstone/shale series and are particularly prevalent during the hurricane season (June–November). The paper reports a study of the rainfall thresholds and landslide susceptibility assessment to assist the prediction, mitigation and management of slope instability in landslide-prone areas of the parish.