Numerical Stress Modeling in Northeastern Brazil
Northeastern Brazil; Intraplate Seismicity; Numerical modeling; flexural stresses
The controlling factors of Intraplate Seismicity (IS) are very discussed and many models have been proposed to explain it such as stress concentration and lithospheric zones of weakness. However, the detailed knowledge of the state of stress and the verification of the contribution of several sources of stress and the role they play into geological features is of fundamental importance in better understanding of IS. Numerical stress modeling is a suitable tool to investigate IS as one can test different source scenarios for the stress field by comparing the results with observed stress data. We model the contribution of deviatoric flexural stresses generated by the topography and density heterogeneities in the observed stress field and seismicity in NE Brazil. Our model consists of horizontally-layered plates above an inviscid fluid (the asthenosphere), where the surface load generated by the topography and bathymetry, and over the internal interfaces of the model (the internal loads) are calculated from the Bouguer anomalies, and the deviatoric flexural stresses are calculated in the Fourier domain. Modeled stresses seems to agree with SHmax data distributed over the study area and predicts normal faulting in the continent and reverse in the sea. Furthermore, relatively high stress concentrations in Pernambuco Lineament agrees with seismicity and the observed faulting style.