Seismic properties of the Nazca oceanic crust in southern Peruvian subduction system

Kim, Young Hee; Clayton, Robert W.

doi:10.1016/j.epsl.2015.07.055

Cited by 17 publications

(11 citation statements)

References 44 publications

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“…Therefore, at least for areas west of our array, the lack of high velocities could simply be an artifact of undersampling. Second, the crust of the subducting Nazca Ridge is very thick (~18 km) [ Hampel et al , ] and possibly hydrated [ Kim and Clayton , ]. The hydrated, overthickened crust and upper sedimentary layers will have low shear wave velocities, which could vertically smear into the oceanic mantle lithosphere in our model, making the expected oceanic‐lithosphere‐related high velocities more difficult to resolve.…”

Section: Discussionmentioning

confidence: 99%

“…In this case the anisotropy is caused by crystallographic and shape-preferred orientation of hydrated fault surfaces [Faccenda et al, 2008] possibly in combination with dehydration and increased pore pressure in these fault zones during subduction [Healy et al, 2009]. Substantial shear wave velocity reduction along the upper part of the subducting plate and/or along the interface between two plates in southern Peru has been recently imaged by Kim and Clayton [2015]. The velocity reduction was interpreted as slab hydration of outer rise faults and subsequent dehydration upon subduction, consistent with this and previous scenarios.…”

Section: Trench-parallel Anisotropy Beneath the Active Volcanic Arcmentioning

confidence: 99%

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Effects of change in slab geometry on the mantle flow and slab fabric in Southern Peru

et al. 2016

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The effects of complex slab geometries on the surrounding mantle flow field are still poorly understood. Here we combine shear wave velocity structure with Rayleigh wave phase anisotropy to examine these effects in southern Peru, where the slab changes its geometry from steep to flat. To the south, where the slab subducts steeply, we find trench‐parallel anisotropy beneath the active volcanic arc that we attribute to the mantle wedge and/or upper portions of the subducting plate. Farther north, beneath the easternmost corner of the flat slab, we observe a pronounced low‐velocity anomaly. This anomaly is caused either by the presence of volatiles and/or flux melting that could result from southward directed, volatile‐rich subslab mantle flow or by increased temperature and/or decompression melting due to small‐scale vertical flow. We also find evidence for mantle flow through the tear north of the subducting Nazca Ridge. Finally, we observe anisotropy patterns associated with the fast velocity anomalies that reveal along strike variations in the slab's internal deformation. The change in slab geometry from steep to flat contorts the subducting plate south of the Nazca Ridge causing an alteration of the slab petrofabric. In contrast, the torn slab to the north still preserves the primary (fossilized) petrofabric first established shortly after plate formation.

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Section: Discussionmentioning

confidence: 99%

Section: Trench-parallel Anisotropy Beneath the Active Volcanic Arcmentioning

confidence: 99%

Effects of change in slab geometry on the mantle flow and slab fabric in Southern Peru

et al. 2016

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“…A thickened incoming plate that is 456 resistant to bending at the trench may result in less slab hydration, potentially limiting 457 melting the mantle wedge and arc formation. However, there is evidence of the opposite 458 being true for the flat-slab section of Peru, where additional hydration causes the slab to 459 be buoyant and release additional water to the mantle wedge than neighboring normally 460 dipping portions of the slab [Kim and Clayton, 2015]. 461…”

Section: Running the Inversion And Its Effects 194mentioning

confidence: 99%

Multiple plates subducting beneath Colombia, as illuminated by seismicity and velocity from the joint inversion of seismic and gravity data

Syracuse

Maceira

Prieto

et al. 2016

Earth and Planetary Science Letters

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“…It should be mentioned that the locations of the earthquakes usually provide a first-order estimate of the geometry of the oceanic trench, however, currently there are more advances, but complicated methods that allow to study in a more adequate way the upper and lower limits of the subduction zone [12,23,25,28], however, for seismic hazard assessments the SSM developed in this work can be used adequately.…”

Section: Figure 12 Cross Sections In the Southern Zone Of Perumentioning

confidence: 99%

Peruvian Subduction Surface Model for Seismic Hazard Assessments

2019

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Throughout the years seismic hazard calculations in Peru have been developed using area sources models, having to date a great variety of models, however, since they are discretized planar models, they cannot adequately represent the continuity and subduction characteristics of the Nazca Plate. The main objective of this work is the developing of a surface subduction model (SSM), useful for seismic hazard assessments as well as the revision and control of previous models used in this sort of assessments. In this study a spatial interpolation was performed employing the Local Polynomial Interpolation method to capture short-range variation in addition to long-range trends. The data base is based on the compilation of seismic catalogs from Peruvian and international institutions such as the IGP, the USGS, the ISC and others, subsequently, in order to have independent events the elimination of duplicate events, aftershocks and foreshocks was carried out. Then, by interpolation of the focal depths of the independent events, a subduction surface model (SSM) was generated as well as a Standard Error Surface which supports a good correlation of the model. Furthermore, 14 transversal sections of the SSM was employed to compare with the hypocenter’s distributions, evidencing a good correlation with the spatial distribution of the events, in addition to adequately capturing the subduction characteristics of the Nazca Plate. Finally, a comparison was made between 2 Peruvian area models for seismic hazard and SSM developed in the present research, evidencing that seismic source models of the area type have deficiencies mainly in the depths they consider, thus is recommended the use of the present model for future seismic hazard assessments.

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Seismic properties of the Nazca oceanic crust in southern Peruvian subduction system

Cited by 17 publications

References 44 publications

Effects of change in slab geometry on the mantle flow and slab fabric in Southern Peru

Effects of change in slab geometry on the mantle flow and slab fabric in Southern Peru

Multiple plates subducting beneath Colombia, as illuminated by seismicity and velocity from the joint inversion of seismic and gravity data

Peruvian Subduction Surface Model for Seismic Hazard Assessments

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