Intra‐plate seismicity and flexural stresses in central Brazil

Explaining intra‐plate seismicity is a challenging task. Different models have been proposed combining weak zones and stress concentration mechanisms. Here we propose that flexural deformation is a major factor to explain seismicity in Central Brazil. A SW‐NE‐oriented seismic zone between the Amazon and the São Francisco cratons coincides with high gravity anomalies, possibly due to a SW‐NE belt of thin crust. The load from the high‐density, shallow mantle rocks causes upper crustal compressional stresses up to 100 MPa in the 200 km wide seismic zone. Away from the central zone of horizontal compression, extensional stresses in the peripheral bulge balance the regional compression explaining the aseismic areas. Three other seismic clusters in Brazil also correlate with high gravity anomalies, suggesting that flexural deformation contributes significantly to explain mid‐plate seismicity in Brazil.