Structure and tectonics in the region of flat subduction beneath central Peru: Crust and uppermost mantle

James, David E.; Snoke, J. Arthur

doi:10.1029/93jb03112

Cited by 31 publications

(29 citation statements)

References 17 publications

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“…The velocity model used in this study is an average of models used in previous earthquake location and seismic imaging studies in the limited parts of the central Andes with available data [e.g., Alvarado et al , 2005; Chinn and Isacks , 1983]. Our model meets the criteria of agreement (±10%) with bulk crustal velocities used in local network seismic studies spanning the forearc to the backarc [e.g., James and Snoke , 1994; Smalley and Isacks , 1990; Legrand et al , 2007].…”

Section: Methodsmentioning

confidence: 99%

Depths and focal mechanisms of crustal earthquakes in the central Andes determined from teleseismic waveform analysis and InSAR

Devlin¹,

Isacks²,

Pritchard³

et al. 2012

Tectonics

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[1] We investigate the depths of crustal earthquakes (<80 km depth) of the central Andes (5°S to 35°S) to constrain the relationship between earthquake locations and inferred faults. We assemble parameters from 138 moderate-sized (7.0 > Mw ≳ 5.5) earthquakes from the Global CMT catalog and previous work spanning 1944-2007. For 38 well-recorded events, we use teleseismic P and SH waveforms to model the strike, dip, rake, focal depth, and source time function. We use InSAR observations of surface deformation from 9 earthquakes to compare inferred fault parameters with the waveform inversions and global catalogs to assess their accuracies. While the depths from the InSAR and waveform analyses generally agree within error, horizontal and depth errors in global catalogs are 10 to 50 km, as found elsewhere. As noted in previous work, the majority of crustal earthquakes occur in the Eastern Cordillera and foreland regions of the central Andes, although a few normal and strike-slip earthquakes occur beneath the Altiplano plateau and in the forearc in southern Peru and northernmost Chile. We propose a new interpretation of one of the basement thrusts (Shira Mountain, Peru) as a pop up block on the basis of our new earthquake depths. We confirm that earthquakes in the flat slab areas of Peru and Argentina are within the sometimes aseismic lower crust. Lower crustal earthquakes are globally found in all types of tectonic settings only when the thermal lithosphere is more than 80 km thick and the amount of recent shortening/extension is <30%.

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Section: Methodsmentioning

confidence: 99%

Depths and focal mechanisms of crustal earthquakes in the central Andes determined from teleseismic waveform analysis and InSAR

Devlin¹,

Isacks²,

Pritchard³

et al. 2012

Tectonics

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“…This basement referred to as Marañon Complex or Marañon "geanticline" [12][13][14]33,54] is affected by vertical faults in the eastern part of the Eastern Cordillera. Near Huancayo, the Huaytapallana fault system uplifted this basement next to the Paleozoic sediments.…”

Section: Geological Structurementioning

confidence: 99%

Mesozoic–Cenozoic Evolution of the Western Margin of South America: Case Study of the Peruvian Andes

Pfiffner

Gonzalez

2013

Geosciences

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Based on the structural style and physiographic criteria, the Central Andes of Peru can be divided into segments running parallel to the Pacific coast. The westernmost segment, the Coastal Belt, consists of a Late Jurassic–Cretaceous volcanic arc sequence that was accreted to the South American craton in Cretaceous times. The Mesozoic strata of the adjacent Western Cordillera represent an ENE-vergent fold-and-thrust belt that formed in Eocene times. Tight upright folds developed above a shallow detachment horizon in the West, while more open folds formed above a deeper detachment horizon towards the East and in the neighboring Central Highlands. A completely different style with steeply dipping reverse faults and open folds affecting the Neoproterozoic crystalline basement is typical for the Eastern Cordillera. The Subandean Zone is characterized by mainly NE-vergent imbricate thrusting which occurred in Neogene times. A quantitative estimate of the shortening of the orogen obtained from balanced cross-sections indicates a total shortening of 120–150 km (24%–27%). This shortening was coevel with the Neogene westward drift of South America, occurred at rates between 3 and 4.7 mm/year and was responsible for the high elevation of the Peruvian Andes

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“…Variation in crustal thickness is also associated with segmentation. In a subhorizontal subduction zone in Peru, between the Western and the Eastern Cordilleras, the crust is about 55 km thick (JAMES and SNOKE, 1994). From 13.5°S-14°S on the crustal thickness increases.…”

Section: Tectonic Settingmentioning

confidence: 99%

Self-similarity in the Seismicity of the South-American Subduction Zone

Cernadas

Osella

Sabbione

1998

Pure appl. geophys.

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The spatial distribution of hypocenters corresponding to intermediate and deep seismicity along the South-American subduction zone has led to a description of the geometry of this subduction process. Changes in the angle of subduction have been detected, which led to a division of the subducted region into segments according to the flat or normal dipping of the oceanic slab.In this paper the seismicity corresponding to the different segments is analyzed in order to determine the kind of correlation with the slab configuration. Spatial analyses using a multifractal technique are performed and the self-similar behavior is quantified through the fractal dimension.Scale-invariant clusterings, with a high correlation between the spatial fractal dimension and the dipping angle of subduction have been found.

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Structure and tectonics in the region of flat subduction beneath central Peru: Crust and uppermost mantle

Cited by 31 publications

References 17 publications

Depths and focal mechanisms of crustal earthquakes in the central Andes determined from teleseismic waveform analysis and InSAR

Depths and focal mechanisms of crustal earthquakes in the central Andes determined from teleseismic waveform analysis and InSAR

Mesozoic–Cenozoic Evolution of the Western Margin of South America: Case Study of the Peruvian Andes

Self-similarity in the Seismicity of the South-American Subduction Zone

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