Abstract

POSADA, Gustavo; MONSALVE, Gaspar  and  ABAD, Ana María. Focal mechanism construction in the north of the Colombian Central Cordillera from record the National Seismological Network of Colombia. Bol. cienc. tierra [online]. 2017, n.42, pp.36-44. ISSN 0120-3630.  https://doi.org/10.15446/rbct.n42.57160.

The collection of waveforms of earthquakes between 2009 and 2015, of local magnitude greater than 4, at stations of the Seismological National Network of Colombia (in Spanish Red Sismológica Nacional de Colombia [RSNC]), occurred on the quadrangle 76°W-74°W and 4°N-8°N (Northern Central Cordillera, centered on the Antioquia Plateau), makes possible the construction of focal mechanisms using first motion polarities of P-wave arrivals on seismograms. The processing was conducted on the Schmidt net, yielding a total of 14 focal mechanisms that were associated with regional faults, with results that suggest two (2) main trends of stress regime: A region between 8°N and 7°N is under a NW-SE compressional stress, while in the south of the study area, between 4°N y 6°N, we mostly observe focal mechanisms that correspond to a strike slip regime.

Keywords : Focal Mechanism; Polarity; P-Wave, Take-off Angle; RSNC..

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