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Seismicity and structure of Nazca Plate subduction zone in southern Peru

Lim, Hobin and Kim, YoungHee and Clayton, Robert W. and Thurber, Clifford H. (2018) Seismicity and structure of Nazca Plate subduction zone in southern Peru. Earth and Planetary Science Letters, 498 . pp. 334-347. ISSN 0012-821X. doi:10.1016/j.epsl.2018.07.014.

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We define subducting plate geometries in the Nazca subduction zone by (re)locating intra-slab earthquakes in southern Peru (14–18°S) and using previously published converted phase analysis results to clarify the slab geometry and inferred relationships to the seismicity. We also provide both P- and S-wave velocity models of the subducting Nazca Plate and mantle layer above the slab using double-difference tomography to understand upper-plate volcanism and subduction zone process. The double-difference constraints for determining the hypocenters and velocity model ensure high accuracy of the relative location of earthquakes with respect to velocity structure. The relocated seismicity shows a smooth contortion in the slab-dip transition zone for ∼400 km between the shallow (30°)-to-flat dipping interface to the northwest and the 30°-dipping interface to the southeast. We find a significant slab-dip difference (up to 10°) between our results and previous slab models along the profile region sampling the horizontal slab at a depth of ∼85–95 km. Robust features in both P- and S-wave tomography inversions are both arc-normal and along-arc velocity variations. In the arc-normal direction, all profile results show that the slab velocities beneath the forearc (down to a depth of ∼100 km) transition to higher velocities beneath the backarc (at ∼100–140 km depth). In the along-arc direction, velocities of the subducting flat slab are shown to be depressed compared to those of the normal-dip slab. In addition, high shear-wave velocities and low Vp/Vs are detected in the mantle layer above the flat slab, indicating its cold and dry environment. Such differences in the velocity structures for the slab and mantle wedge between the two regions may indicate different hydration states, which greatly affects the upper-plate structure of southern Peru.

Item Type:Article
Related URLs:
URLURL TypeDescription
Lim, Hobin0000-0001-7510-4507
Kim, YoungHee0000-0002-1111-632X
Clayton, Robert W.0000-0003-3323-3508
Additional Information:© 2018 Elsevier. Received 31 January 2018, Revised 5 July 2018, Accepted 10 July 2018, Available online 20 July 2018. Editor: M. Ishii We 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). We thank Editor Miaki Ishii and reviewers for comments that greatly improved this paper.
Group:Seismological Laboratory
Funding AgencyGrant Number
Seoul National UniversitySRnD 3345-20160014
Nuclear Safety and Security Commission (Korea)1705010
Subject Keywords:seismicity; subduction zone system; Nazca Plate; relocation; double-difference tomography; southern Peru
Record Number:CaltechAUTHORS:20180720-100400953
Persistent URL:
Official Citation:Hobin Lim, YoungHee Kim, Robert W. Clayton, Clifford H. Thurber, Seismicity and structure of Nazca Plate subduction zone in southern Peru, Earth and Planetary Science Letters, Volume 498, 2018, Pages 334-347, ISSN 0012-821X, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:88052
Deposited By: George Porter
Deposited On:23 Jul 2018 14:47
Last Modified:16 Nov 2021 00:23

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