Resumen de Stress inversion of focal mechanism data using a Bayesian approach: a novel formulation of the right trihedra method
We propose a Bayesian approach for the determination of the stress field from focal mechanism datasets. This method is a revision of the right trihedra method (RTM), used for both fault striation and focal mechanism data. The new probabilistic formulation of the RTM method (BRTM) allows a quantitative estimation of the confidence regions for the principal stress axes. Using an appropriate graphical representation, the method is able to provide simultaneous information about the stress field and its reliability.
Fractures developed in rocks can preserve information about the paleostress field responsible for their own genesis. This information consists of superficial structures (e.g., striations, accretion steps, tool marks) and/or secondary fractures of the fault plane (tension fractures -T- and shear fractures -R-R'-P-; sensu Petit, 1987). All these structures are useful to evaluate the fault kinematic, which is the first essential step to perform a fault-slip or striation analysis (Angelier and Mecheler, 1977; Petit, 1987; Ramsay and Lisle, 2000).
During recent decades, techniques conceived for mesostructural analyses were revised for the processing of earthquake focal mechanism datasets. Under specific conditions, this procedure allows retrieval of the seismotectonic stress (e.g., McKenzie, 1969; Gephart and Forsyth, 1984; Carey-Gailhardis and Mercier, 1987; Michael, 1987; Angelier, 2002; Célérier et al., 2012).
The stress inversion is a procedure that, using observed fault kinematics and/or focal mechanisms, allows the reconstruction of the stress field. Such techniques are a successful tool for stress-field reconstruction in areas of active tectonics (e.g., Angelier and Mecheler, 1977; Angelier, 1984; Di Bucci et al., 2006; Shabanian et al., 2010).
