Intra-plate seismicity and flexural stresses in central Brazil

Author(s)

Assumpcao, Marcelo ^[1] ; Sacek, Victor ^[2]

Affiliation

^[1] Univ Sao Paulo. Inst Astron Geophys & Atmospher Sci

^[2] Univ Sao Paulo. Inst Astron Geophys & Atmospher Sci

• Document type: Journal article
• Source: Geophysical Research Letters; v. 40, n. 3, p. 487-491, FEB 16 2013.
• Web of Science Citations: 4

Abstract

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 Sao 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. Citation: Assumpcao, M., and V. Sacek (2013), Intra-plate seismicity and flexural stresses in central Brazil, Geophys. Res. Lett., 40, 487-491, doi:10.1002/grl.50142. (AU)

• FAPESP's process: 11/10400-0 - Tectonic, climatic and erosional evolution in convergent margins: a numerical approach
• Grantee: Victor Sacek
• Support Opportunities: Scholarships in Brazil - Post-Doctoral