Overlapping slabs: Untangling subduction in NW South America through finite-frequency teleseismic tomography

Meng Sun, Maximiliano J. Bezada, John Cornthwaite, German A. Prieto, Fenglin Niu, Alan Levander

Research output: Contribution to journalArticlepeer-review

Abstract

Both the Caribbean and Nazca plates subduct beneath northwestern South America. The configuration of the two subducted slabs and the nature of any interaction between them has long been a matter of debate. Based on the location of intermediate-depth seismicity and active and extinct volcanism, as well as on seismic imaging, several different tectonic scenarios have been proposed. In this paper, we use teleseismic data recorded by the Colombian National Network and the temporary CARMA array in Venezuela and Colombia to produce a finite-frequency tomography model for the region. Our results show several distinct subduction segments. Through synthetic tests, we show that our results require a zone of overlap between Nazca and Caribbean subduction north of the “Caldas Tear” as has been proposed by previous studies. Additionally, we find that the Bucaramanga Nest occurs within the Caribbean Plate and coincides with bending of the slab in two planes, where both the strike and the dip of the slab change. We infer that elevated stresses are an important factor in producing the very high rates of seismicity in the nest.

Original languageEnglish (US)
Article number117253
JournalEarth and Planetary Science Letters
Volume577
DOIs
StatePublished - Jan 1 2022

Bibliographical note

Funding Information:
We thank the Colombian Geological Service and the Venezuelan Foundation for Seismological research for providing data from their permanent and temporary stations and for their operation of the CARMA seismic array. The US seismic instruments were provided by the Incorporated Research Institutions for Seismology (IRIS) through the PASSCAL Instrument Center. The facilities of the IRIS Consortium are supported by the National Science Foundation 's Seismological Facilities for the Advancement of Geoscience (SAGE) Award under Cooperative Support Agreement EAR-1851048 . This research was partly supported by the National Science Foundation under Grant No. EAR-1459047 . We thank two anonymous reviewers who provided valuable feedback that helped improve the manuscript.

Funding Information:
We thank the Colombian Geological Service and the Venezuelan Foundation for Seismological research for providing data from their permanent and temporary stations and for their operation of the CARMA seismic array. The US seismic instruments were provided by the Incorporated Research Institutions for Seismology (IRIS) through the PASSCAL Instrument Center. The facilities of the IRIS Consortium are supported by the National Science Foundation's Seismological Facilities for the Advancement of Geoscience (SAGE) Award under Cooperative Support Agreement EAR-1851048. This research was partly supported by the National Science Foundation under Grant No. EAR-1459047. We thank two anonymous reviewers who provided valuable feedback that helped improve the manuscript.

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

  • Caribbean
  • flat slab
  • Nazca
  • northern Andes
  • northern South America
  • subduction

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