Seismic hazard analysis of Adjara region in Georgia

Seismic hazard assessment is a very important issue for seismic design and engineering projects. Generally, probabilistic seismic hazard assessment (PSHA) is used for such kind of studies, which gives a probabilistic description of earthquake characteristics such as selected ground motion parameter (peak ground acceleration or spectral acceleration), against the annual frequency of exceedance (or its reciprocal, return period) and fault displacement. The design value is the ground motion level that corresponds to the preselected design return period. For many engineering projects, standard buildings and typical bridges, the seismic loading is taken from the appropriate seismic design code, the basis of which is usually a PSHA. Each step necessary for PSHA was studied separately: active tectonic settings that are the reason of moderate seismicity in Caucasus Region, seismicity, magnitude–distance distributions, ground motion prediction models, etc. As a result, calculation of probabilistic seismic hazard was performed using Software CRISIS2007 by Ordaz (Instituto de Ingeniería, UNAM, Mexico, 2007). CRISIS offers many advantages at different stages of PSHA. Our study shows that in case of Adjara region, significant contribution to seismic hazard comes from local sources with quite low M max values.