Uniform hazard spectra estimation in Peru

The spectra described in the Peruvian Seismic Design Code are based on scaling the ordinates of a standard spectrum at the peak ground acceleration. This scaling leads to a non-uniform hazard distribution in the spectra and may produce structural designs with different failure probability. In this study, we have developed maps of probabilistic values of peak horizontal ground acceleration (PGA) and spectral accelerations (SA) at 0.2 and 1.0 sec periods (5% of critical damping) with 10% probability of exceedance in 50 years. The maps were developed based on an exponential magnitude distribution and Youngs's attenuation relationship for subduction earthquakes. Based on the maps for spectral acceleration, uniform hazard spectra can be estimated for any site in Peru. Also, detailed spectral shapes were evaluated for three cities in Peru and compared with those specified by the Peruvian seismic code.