Seismic structure and tectonics of the continental wedge overlying the source region of the Iquique Mw8.1 2014 earthquake

Reginato, G.; Vera, E.; Contreras‐Reyes, Eduardo; Tréhu, A. M.; Maksymowicz, Andrei; Bello-González, Juan Pablo; González, Felipe

doi:10.1016/j.tecto.2020.228629

Cited by 15 publications

(8 citation statements)

References 55 publications

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“…These observations are consistent with the sediment starved, erosive subduction thought to be occurring offshore northern Chile (Contreras-Reyes et al, 2014;Geersen et al, 2018;Rutland, 1971;von Huene & Scholl, 1991) and other coincident MCS imaging (Geersen et al, 2018;Petersen et al, 2021;Storch et al, 2021). While over-riding plate velocities are only constrained in a small area by Pg arrivals, they are comparable to velocities of the deformation front and over-riding plate determined from another, nearby PICTURES profile (Reginato et al, 2020).…”

Section: Overview Of the Preferred Tomographic Velocity Modelsupporting

confidence: 85%

“…As part of the eroded forearc wedge, this region may host a hydro-fractured base of the upper crust near the plate interface, indicated by low seismic velocities below the coastline (Sick et al, 2006). Reginato et al (2020) and Storch et al (2021) propose that along-dip zoning of density and associated stress first introduced by Maksymowicz et al (2018) indicate that the highly fractured frontal prism acts as an aseismic barrier to the more seismically active, less fractured middle slope. Petersen et al (2021) use select PICTURES reflection imaging and OBS-recorded aftershocks to further correlate the distribution of upper plate normal faulting and a weak, aseismic outer wedge with proposed subduction erosion at the base of the wedge.…”

Section: Tectonic Settingmentioning

confidence: 99%

“…Reginato et al. (2020) and Storch et al. (2021) propose that along‐dip zoning of density and associated stress first introduced by Maksymowicz et al.…”

Section: Tectonic Settingmentioning

confidence: 99%

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Crustal Structure of the Incoming Iquique Ridge Offshore Northern Chile

et al. 2022

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The Peru‐Chile subduction zone hosts M > 8 earthquakes as well as multiple ridges on the downgoing Nazca plate, making this region well suited for investigating the formation, evolution, and potential impacts of subducting features on seismogenesis. To evaluate the physical properties and structural variability of the Iquique Ridge offshore northern Chile, we present a P wave velocity model of the Nazca plate and Iquique Ridge outboard of the 2014 M 8.1 Iquique earthquake sequence. 2D tomographic inversions of P wave traveltime data from the 2016 PICTURES (Pisagua/Iquique Crustal Tomography to Understand the Region of the Earthquake Source) controlled‐source experiment indicate that the Iquique Ridge is characterized by significant crustal thickening relative to typical Nazca plate oceanic crust, with a maximum thickness of ∼13 km beneath the most prominent portion of the Iquique Ridge and outer rise. Reduced upper crustal seismic velocities extend from the ridge eastward to the trench, which may indicate increased fracturing and/or hydration during plate bending. Corresponding multi‐channel seismic reflection data show along‐profile structural variation as well, including an intermittent Moho reflector near the onset of crustal thickening and faulting along the landward slope. The structural heterogeneity entering the Peru‐Chile Trench has potential implications for slip behavior at depth assuming that the anomalous crustal structure continues beneath the forearc. We suggest that the increased buoyant normal force associated with discrete subducted Iquique Ridge seamounts similar to the zone of thick crust imaged here could lead to localized increased interplate coupling, while entrained sediment and fractured/altered crust could facilitate aseismic slip.

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Section: Overview Of the Preferred Tomographic Velocity Modelsupporting

confidence: 85%

Section: Tectonic Settingmentioning

confidence: 99%

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Crustal Structure of the Incoming Iquique Ridge Offshore Northern Chile

et al. 2022

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“…Between 50 and 70 km from the trench, a series of pronounced seaward dipping normal faults cut from the seafloor into the framework rock of the upper plate (dashed lines; Figure 2b). Their locations correlate to some of the aftershock hypocenters in the upper plate (also compare Reginato et al, 2020).…”

Section: Marine Forearc Structure and Active Tectonics In The 2014 Iquique Earthquake Regionmentioning

confidence: 81%

Relationship Between Subduction Erosion and the Up‐Dip Limit of the 2014 Mw 8.1 Iquique Earthquake

Petersen

Lange

et al. 2021

Geophysical Research Letters

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The aftershock distribution of the 2014 Mw 8.1 Iquique earthquake offshore northern Chile, identified from a long‐term deployment of ocean bottom seismometers installed eight months after the mainshock, in conjunction with seismic reflection imaging, provides insights into the processes regulating the updip limit of coseismic rupture propagation. Aftershocks updip of the mainshock hypocenter frequently occur in the upper plate and are associated with normal faults identified from seismic reflection data. We propose that aftershock seismicity near the plate boundary documents subduction erosion that removes mass from the base of the wedge and results in normal faulting in the upper plate. The combination of very little or no sediment accretion and subduction erosion over millions of years has resulted in a very weak and aseismic frontal wedge. Our observations thus link the shallow subduction zone seismicity to subduction erosion processes that control the evolution of the overriding plate.

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“…The interplay between the physical segmentation of the continental wedge and seimotectonics of the margin is also reflected by the spatial correlation of large marine forearc basins and low‐ and high‐gravity anomalies with the rupture areas of large earthquakes and location of high slip patches (Bassett & Watts, 2015; Bassett et al., 2016; Reginato et al., 2020; Schurr et al., 2020; Song & Simons, 2003; Wells et al., 2003). This suggests that the variations in normal stresses over the seismogenic contact generated by large changes in the overriding plate density play a key role in the complex process of megathrust activation during the seismic cycle (Li & Liu, 2017; Maksymowicz et al., 2015; Tassara, 2010).…”

Section: Introductionmentioning

confidence: 99%