TRIGRS

USGS TRIGRS computes, cell by cell on a raster, how rainfall infiltration changes pore pressure and the infinite-slope factor of safety, showing when and where shallow landslides are likely. It handles saturated and unsaturated soils, variable rainfall and surface-runoff routing, and comes with utilities for preparing grids plus a parallel (MPI) version for large areas. Suited to geotechnical engineers and geologists producing landslide hazard maps along roads and in catchments. Limitations: it is a command-line program distributed as Fortran source code, so it must be compiled; inputs and results are prepared and viewed in separate GIS software; choosing parameters requires engineering judgement.