Seismic attenuation structure of southern Peruvian subduction system
Abstract
Seismic attenuation provides key constraints on understanding the structure and dynamics of subduction-zone system. In this study, we provide the first three-dimensional P and S-wave attenuation models beneath the Nazca-South America subduction zone by inverting t* data from 397 local shallow and intermediate-depth earthquakes. The study area covers the southern part of the Peruvian flat-slab region (11°–15 °S) (where the subducting Nazca Ridge is migrating), and the Central Andean Plateau (∼13°–18 °S) (associated with the subducting Nazca Plate) and the Brazilian mantle lithosphere. We obtain five major features in our attenuation model with seismicity including (1) well-defined along-strike and along-dip Nazca slab structure in terms of low attenuation, (2) high attenuation associated with the passage of Nazca Ridge and present location of the oceanic ridges, (3) high attenuation in the backarc mantle wedge and continental crust, (4) clear image of Brazilian Shield in terms of low attenuation, underthrusting to the west, and (5) high attenuation related to the slab dehydration beneath the volcanic arc at 100 and 200 km depths. In particular, prominent low-Q zones in the continental crust and mantle wedge beneath the active volcanic arc reflect source zones of arc magmatism caused by fluids from the slab dehydration. The observed along-arc differences in slab Q estimates can be attributed to different hydration states between the flat and normal-dip slabs due to the subduction of the Nazca Ridge.
Additional Information
© 2019 Elsevier B.V. Received 1 August 2019, Revised 14 September 2019, Accepted 14 September 2019, Available online 8 November 2019. H. Jang, Y. Kim, and H. Lim acknowledge Creative-Pioneering Researchers Program through Seoul National University (SNU SRnD 3345-20160014), and the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety (KoFONS), granted financial resource from the Nuclear Safety and Security Commission (NSSC), Republic of Korea (No. 1705010). The authors are grateful to the many institutions that deployed and maintained temporary networks in southern Peru and northwestern Bolivia. In particular, the authors thank the Peru Subduction Experiment (PeruSE) for providing the seismic waveform data used in this study. Seismic instruments for the Central Andean Uplift and Geodynamics of High Topography (CAUGHT) and the Peru Lithosphere and Slab Experiment (PULSE) experiments were provided by the Incorporated Research Institutions for Seismology (IRIS) through the Program for the Array Seismic Studies of the Continental Lithosphere (PASSCAL) Instrument Center at the New Mexico Institute of Mining and Technology. Finally, the authors thank Editor Kelin Wang and the two reviewers for their comments, which greatly improved this article.Attached Files
Supplemental Material - 1-s2.0-S004019511930318X-mmc1.docx
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Additional details
- Eprint ID
- 99762
- Resolver ID
- CaltechAUTHORS:20191111-073558672
- Seoul National University
- SNU SRnD 3345-20160014
- Korea Foundation of Nuclear Safety
- Nuclear Safety and Security Commission (Korea)
- 1705010
- Created
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2019-11-12Created from EPrint's datestamp field
- Updated
-
2021-11-16Created from EPrint's last_modified field
- Caltech groups
- Seismological Laboratory, Division of Geological and Planetary Sciences