Seismotectonics of Sierra Pie de Palo, a basement block uplift in the Andean foreland of Argentina


A digitally recording seismic network was operated from September 1987 to May 1988 in the San Juan Province of northwestern Argentina. The data provide a detailed view of the crustal seismicity of Sierra Pie de Palo, one of the most seismically active mountain blocks of the Sierra Pampeanas and the site of the destructive Ms 7.3 Caucete earthquake in 1977. The morphology of the range, seismicity pattern, and focal mechanisms strongly suggest Sierra Pie de Palo is cut into two blocks by a northeast-southwest striking fracture. In the northern block, seismicity occurs along a well-defined west-dipping seismic zone, while the southern block is characterized by east-dipping seismic layers. Both dipping zones connect to a subhorizontal mid-crustal detachment that we interpret as the lower boundary of the brittle failure domain. Local boundary effects within the Sierras Pampeanas Province partially control the shortening direction in the crust. -from Authors

Publication Title

Bulletin - Seismological Society of America

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