Seismicity structure of the Northern Chile forearc from >100,000 double-difference relocated hypocenters

C. Sippl, B. Schurr, G. Asch and J. Kummerow – 2018

Title
Seismicity structure of the Northern Chile forearc from >100,000 double-difference relocated hypocenters
Author
C. Sippl, B. Schurr, G. Asch and J. Kummerow
Date
2018
Citation
Sippl et al., 2018, Seismicity structure of the Northern Chile forearc from >100,000 double-difference relocated hypocenters, Journal of Geophysical Research: Solid Earth
Language
eng
Type
Text
BibTeX Code
@article{doi:10.1002/2017JB015384,
author = {Sippl C. and Schurr B. and Asch G. and Kummerow J.},
title = {Seismicity structure of the Northern Chile forearc from >100,000 double-difference relocated hypocenters},
journal = {Journal of Geophysical Research: Solid Earth},
year = {2018},
volume = {0},
number = {ja},
pages = {},
keywords = {Subduction Zone, Seismicity, Intermediate‐depth earthquakes, Northern Chile, Slab hydration},
doi = {10.1002/2017JB015384},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017JB015384},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017JB015384},
abstract = {Abstract In this study, we present high‐resolution seismicity images of the Northern Chile subduction zone forearc. We used eight years of continuous seismic waveform data from the IPOC network and auxiliary stations to produce an extensive earthquake catalog containing 101,601 double‐difference relocated earthquake hypocenters using automatic event detection and phase picking routines. The minimum magnitude of retrieved events is <2, and the catalog is estimated to be complete at magnitudes above ∼2.8. Intraslab seismicity makes up the majority of detected earthquakes. Where the seismogenic zone of the megathrust is active, a clear separation of seismicity into three distinct planes can be observed. The uppermost plane corresponds to the plate interface, which is observed to terminate downdip at a depth of 50‐55 km. The other two planes, located ∼7 and ∼26 km below the slab surface, dip at a constant angle of about 20° until they are absorbed by a 25 km thick highly active cluster of intermediate‐depth seismicity at depths of 80‐120 km. Downdip of this cluster, the slab steepens and lower plate seismicity is considerably sparser, even absent in the northern part of the study area. Upper plate seismicity is also considerable, with a segment between 21 and 21.6° S standing out for featuring pervasive activity occurring all the way down to the plate interface. Here, the seismicity resembles a wedge in west‐east profile view, and occurs where the upper plate crust is coldest based on thermal models.}
}