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Tectonic deformation of the Andes and the configuration of the subducted slab in central Peru: Results from a micro-seismic experimentThe vast majority of the microearthquakes recorded occurred to the east: on the Huaytapallana fault in the Eastern Cordillera or in the western margin of the sub-Andes. The sub-Andes appear to be the physiographic province subjected to the most intense seismic deformation. Focal depths for the crustal events here are as deep as 50 km, and the fault plane solutions, show thrust faulting on steep planes oriented roughly north-south. The Huaytapallana fault in the Cordillera Oriental also shows relatively high seismicity along a northeast-southwest trend that agrees with the fault scarp and the east dipping nodal plane of two large earthquakes that occurred on this fault in 1969. The recorded microearthquakes of intermediate depth show a flat seismic zone about 25 km thick at a depth of about 100 km. This agrees with the suggestion that beneath Peru the slab first dips at an angle of 30 deg to a depth of 100 km and then flattens following a quasi-horizontal trajectory. Fault plane solutions of intermediate depth microearthquakes have horizontal T axes oriented east-west.
Document ID
19840012904
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Suarez, G. (Massachusetts Inst. of Tech. Cambridge, MA, United States)
Gagnepain, J. J. (Paris VI Univ. Cambridge, MA, United States)
Cisternas, A. (Paris VI Univ. Lima, United States)
Hatzfeld, D. (Grenoble-1 Univ. Cambridge, MA, United States)
Molnar, P. (Massachusetts Inst. of Tech.)
Ocola, L. (Instituto Geofisico del Peru)
Roecker, S. W. (Massachusetts Inst. of Tech.)
Viode, J. P. (Paris VI Univ.)
Date Acquired
September 4, 2013
Publication Date
January 1, 1983
Subject Category
Geophysics
Report/Patent Number
NASA-CR-175445
NAS 1.26:175445
Accession Number
84N20972
Funding Number(s)
CONTRACT_GRANT: NAG5-300
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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