REASSESS V1.0: A COMPUTATIONALLY-EFFICIENT SOFTWARE FOR PROBABILISTIC SEISMIC HAZARD ANALYSIS

A stand-alone software for the probabilistic assessment of seismic hazard is developing. In its final version, it shall be structured in three modules for: (i) site-specific, (ii) scenario-based and (iii) multi-site (regional) analyses. This paper focuses on (i), which is devoted to single-site probabilistic seismic hazard analysis (PSHA). Seismic sources can be either zones or individual faults. The algorithm to compute PSHA is implemented assuming, classically, that the process of occurrence of earthquakes on each seismic source follows a homogeneous Poisson process; the processes for different sources are independent. The required input data are: (1) the source(s) geometry and the annual rate(s) of occurrence of earthquakes in the magnitude interval of interest; (2) the distribution of magnitude given the occurrence of one earthquake; (3) the ground motion propagation model (GMPM); (4) the soil classification at the site for which hazard is evaluated. Regarding (1-3), the user is aided by some library implemented in the software. REASSESS also is able to account for model uncertainty, in fact, logic trees can be built based on alternatives for the source’s annual rate of earthquake occurrence, magnitude distribution and GMPM. The strength of REASSESS, beyond the user-friendly interface, stays in the PSHA computation algorithms. These have been coded in MATLAB®, targeting accuracy and reduced computing time. Its potential for earthquake engineering and engineering seismology applications is illustrated by a few applications discussed in the paper.