Reverse faulting in the Isthmus of Tehuantepec: Backarc deformation induced by the subduction of the Tehuantepec ridge
Por:
Suárez G.
Publicada:
1 ene 2000
Resumen:
The seismicity in the Gulf of Mexico is sparse. There is, however, a cluster of shallow crustal seismicity in the northern part of the Isthmus of Tehuantepec. Two earthquakes occurring in this band of seismic activity are large enough to be studied in detail using a formal inversion algorithm that gleans the best-fitting centroidal focal depth and source mechanism from the radiated P and SH waves. The resulting mechanisms indicate reverse faulting with axes of maximum compression oriented northeast-southwest, subparallel to the direction of relative plate motion in the subduction zone to the south. The presence of these reverse-faulting earthquakes suggests deformation of the backarc in the northern Isthmus of Tehuantepec. The horizontal compressive stress transmitted to the upper continental plate by the subduction of the Cocos plate is apparently enhanced here by the presence of the Tehuantepec ridge, a feature of high bathymetric relief on the subducting Cocos plate. The collision of the ridge with the North American plate apparently produces not only the backarc deformation reflected by this seismicity, but also a northward deflection of the trench and of the coastline on the Pacific Ocean.
Filiaciones:
Suárez G.:
Instituto de Geofísica, Universidad Nacional Autónoma de México, Mexico D. F., Mexico
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