TRIGRS version 2.1

The Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Model (TRIGRS) is a Fortran program designed for modeling the timing and distribution of shallow, rainfall-induced landslides. The program computes transient pore-pressure changes, and attendant changes in the factor of safety, due to rainfall infiltration. This release, 2.1.0a, includes bug fixes, new output formats, and various optimizations to improve performance of the TRIGRS serial code. These improvements have also been incorporated into a new parallel implementation of the TRIGRS program (Alvioli and Baum, 2016, see http://dx.doi.org/10.1016/j.envsoft.2016.04.002). We have parallelized the four time-demanding execution modes of TRIGRS, namely both the saturated and unsaturated model with finite and infinite soil depth options, within the Message Passing Interface (MPI) framework.