The Brazilian territory presents low seismicity, typical of a tectonic intra-plates region. Nevertheless, the seismic effects cannot be simply disre- garded in the engineering projects. Therefore, a study is presented in this paper, of the seismicity of the Brazilian Northeastern Region, which due to its proximity with the South Atlantic Ridge, presents a seismic activity rate higher than of other Brazilian regions. In this way, the seismic recur- rences and the probabilistic distribution functions of spectral accelerations are determined for the region. From the obtained values, the design response spectra are defined for the region, being its values compared, for several periods, with the design spectrum presented by the Brazilian Seismic Standard NBR 15421.
seismic hazard; seismic engineering; hazard anaysis