sismoazur_logo logo_resif

FMNEAR is a method to invert for double couple focal mechanisms in a fully automatic way, based on the modelling of bandpass filtered displacement waveforms of broadband and strong motion records. Depending on magnitude, the source is represented either by a point source (M < 5.5) or by a linear extended source model oriented along fault strike (M > 5.5). The use of an extended source model allows us to model the waveforms of large earthquakes using near source strong motion records. The parameter space for the strike, dip, and rake parameters of the focal mechanism is explored in a non linear way allowing the evaluation of the degree of uniqueness of the solution, which is quantified through a 'confidence index'. Source depth and moment magnitude (Mw) are also recomputed. The overall quality of the solution is indicated by a letter, A, B, C based on the index of confidence and the number of components used. A means that the focal mechanism is strongly constrained, B well constrained, C moderately constrained. Solutions too poorly constrained are not shown.

Reference: Delouis, B., 2014. FMNEAR: determination of focal mechanism and first estimate of rupture directivity using near source records and a linear distribution of point sources, Bulletin of the Seismological Society of America, 104 (3), 1479-1500, doi:10.1785/0120130151.