Sismicidade do Nordeste do Brasil

Abstract

A revised catalogue of earthquakes, which occurred in the Northeastern region of Brazil up to 1980, is presented. Most of the data come from historical macro seismic information collected in old publications and newspapers. Recent instrumental data is used to derive empirical relations between magnitude and felt area in order to estimate m5 magnitudes f<¡r the events not recorded by seismographic stations. Macro seismic data for two large events (Pereira 23'02.68, and Pacalus 20. 1f .80) are presented in detail. Epicenters of four recent events recorded at NAT were determined by combining the macro seismic and instrumental data and used to define a preliminary value of the ratio K=VIP/Vs=1.77 for the region under study. A swarm of activity at Pyrazino, Rio Grande do Norte, was studied in more detail to estimate the parameter ó of the Gutenberg and Richter frequency: magnitude relation.