Stress distribution and geometry of the subducting Nazca plate in northern Chile using teleseismically recorded earthquakes
Por:
Comte D., Suárez G.
Publicada:
1 ene 1995
Resumen:
The stress distribution along the subducting Nazca plate in northern Chile is analysed using focal mechanism solutions obtained from the inversion of long-period P, SV, and SH waveforms of 15 earthquakes, and from 212 events with reported focal mechanisms, which occurred between 1962 and 1993. A change from tensional to compressional stress field along the upper part of the subducting slab is associated with the maximum depth extent of the coupled zone. This change occurs in northern Chile at ~200-250 km from the trench, at depths of ~60 ± 10 km. Seismic slip probably extends down to 40 km in depth. The shallow dip angle of the Wadati-Benioff zone does not show variations along the strike of the trench. However, a gradual southward flattening of the slab is observed at distances greater than 200-250 km from the trench. There are two gaps located between the three main clusters of seismicity; these gaps are clearly not related to detachments in the descending lithosphere. These gaps could be associated with alternating changes from compressional to tensional stress field in the subducting slab. -from Authors
Filiaciones:
Comte D.:
Departamento de Geofísica, Universidad de Chile, Casilla 2777, Santiago, Chile
Suárez G.:
Instituto de Geofísica, Universidad Nacional Autónoma de México, Apartado Postal 70-172, México, Distrito Federal, 04510, Mexico
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