A comparison of the Brazilian regional magnitude, mR, with the teleseismic mb for intraplate sub-Andean earthquakes

Intraplate earthquakes in Brazil are often measured with the P-wave regional magnitude mR, a scale developed for the attenuation characteristics of the Brazilian stable cratonic lithosphere. In the range 3.5 to 5.5, the regional magnitude compares well with the short-period P-wave teleseismic magnitude mb. Many crustal earthquakes in the sub-Andean region are recorded by the Brazilian Seismic Network (RSBR) with paths crossing mostly the stable continental interior. We compared the regional magnitudes mR of sub-Andean events, measured by RSBR, with the teleseismic mb to see if mR would be applicable to subAndean events. The RSBR mR magnitudes tend to be 0.5 units lower than the ISC mb values. This may imply that the upper mantle beneath the sub-Andean region attenuates P waves more strongly than the Brazilian lithosphere.