Abstract
Application of satellite geodesy in CASA campaigns of 1991, 1994, and 1996, and stress inversion analysis of 96 focal mechanisms for the period 1976-2000 obtained at Harvard University (Mw > 5), allowed establishment of a compressive tendency in the west-east sense of the Panama-Costa Rica Block (BPC), impacting the North Andes Block (BNA). Nevertheless, some seismic evidence would allow confirming the existence of the proposed Chocó Block (BC), with the western limit at the Darién Range, and eastern limit in the Murindó zone, demonstrated by stress inversion in these two zones, with sub-parallel north-south tendency. The southern limit, at 4º N, also shows stress with north-south tendency. Some surface earthquakes located on the Pacific Coast, apparently the western limit of the Chocó Block, show stress with NW tendency. Additionally, the displacement vectors and main stress axes in the Colombian southwest, near the Tumaco zone, show clear west-east tendencies. Finally, deep seismicity in the Bucaramanga zone displays stress with NNW-SSE tendency, coherent with the Caribbean Plate subduction under South America.
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References
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