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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 at local to regional epicentral distance. 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.

FMNEAR inversion is triggered by the localization of a new event, either by sismoazur (focused on south-east France and neighboring areas), or by the EMSC (global scale). Different trigger magnitude thresholds are used depending on the geographical area. If too few records at local to regional distance are available from the open data centers, no solution will be provided. This catalogue of focal mechanisms will be far from exhaustive.


Solutions are computed in a fully automated way and published here without revision

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.