Crustal structure of north Peru from analysis of teleseismic receiver functions

Cristobal Condori Quispe, George S. França, Hernando J. Tavera, Diogo F. Albuquerque, Brandon T. Bishop, Susan L. Beck

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Abstract

In this study, we present results from teleseismic receiver functions, in order to investigate the crustal thickness and Vp/Vs ratio beneath northern Peru. A total number of 981 receiver functions were analyzed, from data recorded by 28 broadband seismic stations from the Peruvian permanent seismic network, the regional temporary SisNort network and one CTBTO station. The Moho depth and average crustal Vp/Vs ratio were determined at each station using the H-k stacking technique to identify the arrival times of primary P to S conversion and crustal reverberations (PpPms, PpSs + PsPms). The results show that the Moho depth correlates well with the surface topography and varies significantly from west to east, showing a shallow depth of around 25 km near the coast, a maximum depth of 55–60 km beneath the Andean Cordillera, and a depth of 35–40 km further to the east in the Amazonian Basin. The bulk crustal Vp/Vs ratio ranges between 1.60 and 1.88 with the mean of 1.75. Higher values between 1.75 and 1.88 are found beneath the Eastern and Western Cordilleras, consistent with a mafic composition in the lower crust. In contrast values vary from 1.60 to 1.75 in the extreme flanks of the Eastern and Western Cordillera indicating a felsic composition. We find a positive relationship between crustal thickness, Vp/Vs ratio, the Bouguer anomaly, and topography. These results are consistent with previous studies in other parts of Peru (central and southern regions) and provide the first crustal thickness estimates for the high cordillera in northern Peru.

Original languageEnglish
Pages (from-to)11-24
Number of pages14
JournalJournal of South American Earth Sciences
Volume76
DOIs
StatePublished - 1 Jul 2017
Externally publishedYes

Bibliographical note

Funding Information:
The data used in this study were provided by the Peruvian National Seismic Network and the Instituto Geof?sico del Per?. This research was supported by CAPES. We would like to thank the Observatorio Sismol?gico-OBSIS and Universidade de Bras?lia-UnB. We also thank Marcelo Assump??o (IAG-USP) for providing compiled data of crustal thickness for adjacent regions to our study area and for valuable contributions to the manuscript. We also thank to Marcelo Peres for his contributions. GSF thanks CNPq for his PQ grants (307255/2013-1).

Publisher Copyright:
© 2017 Elsevier Ltd

Keywords

  • Crustal thickness
  • Northern Peru
  • Receiver function
  • Vp/Vs ratio

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