Urban landslide hazard

Even without climate change, the susceptibility of slopes to landslides is being increased by development activities involving earthworks (cuts and fills) and construction—whether planned or unauthorized. These activities change slope geometry, strength, loading, vegetation cover, and surface water and groundwater regimes. Thus, the process of development can increase the physical landslide hazard while exposing more of the most vulnerable people and structures to these hazards. To address landslide-related losses, and the interaction of development activities with slope stability, this accumulation of risk must be tackled. The ability to mitigate small events effectively, or to limit their impact, could result in an increased capacity to manage the risks associated with larger events.

With respect to rainfall-triggered landslide risk, the Caribbean (where Mossaic has been developed) is typical of many developing regions in the humid tropics. The steep slopes and deep soils that characterize much of this region are naturally prone to landslides, which are triggered by high-intensity or high-duration rainfall .

A combination of poverty and increasing levels of urbanization is resulting in the construction of unauthorized settlements on such slopes, as they are often the only available location for the the most vulnerable. Like many other developing countries, certain urban areas in Latin America and the Caribbean suffer from low-quality housing, inadequate (or unenforced) urban planning controls, and insufficient investment in infrastructure. The resulting landslide risk is the product of complex interactions between the inherent susceptibility of slopes to landslides (related to their soils and geology, topography, hydrology, and vegetation), the influence of human activities in affecting these factors at a highly localized scale, and the vulnerability of communities to the impact of landslides.