Imaging subducted slab structure beneath the Sea of Okhotsk with teleseismic waveforms

Zhan, Zhongwen; Helmberger, Donald V.; Li, Dunzhu

doi:10.1016/j.pepi.2014.03.008

Cited by 24 publications

(25 citation statements)

References 40 publications

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“…Journal of Geophysical Research: Solid Earth of~3-5% from previous waveform modeling studies for the dipping part of the subducted slab (Chen et al, 2007;Ding & Grand, 1994;Zhan et al, 2014). We also noticed that in these two recent tomographic models, the stagnant slab has a smaller velocity anomaly than the dipping part.…”

Section: 1029/2018jb016642supporting

confidence: 61%

“…We first tested our initial model by P wave triplicated waveform modeling for all the three events and then further verified and refined our model by S wave triplicated waveform modeling (next section). The recent two tomographic studies (Fukao & Obayashi, ; Tang et al, ) report ~+1% and ~+1.5% P wave velocity anomaly for the stagnant and downgoing slab, respectively, which are typically smaller than the results of ~3–5% from previous waveform modeling studies for the dipping part of the subducted slab (Chen et al, ; Ding & Grand, ; Zhan et al, ). We also noticed that in these two recent tomographic models, the stagnant slab has a smaller velocity anomaly than the dipping part.…”

Section: Construction Of the 2‐d Slab Modelmentioning

confidence: 79%

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Mantle Transition Zone Structure Beneath Northeast Asia From 2‐D Triplicated Waveform Modeling: Implication for a Segmented Stagnant Slab

et al. 2019

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The structure of the mantle transition zone (MTZ) in subduction zones is essential for understanding subduction dynamics in the deep mantle and its surface responses. We constructed the P (Vp) and SH velocity (Vs) structure images of the MTZ beneath Northeast Asia based on two‐dimensional (2‐D) triplicated waveform modeling. In the upper MTZ, a normal Vp but 2.5% low Vs layer compared with IASP91 are required by the triplication data. In the lower MTZ, our results show a relatively higher‐velocity layer (+2% Vp and −0.5% Vs compared to IASP91) with a thickness of ~140 km and length of ~1,200 km atop the 660‐km discontinuity. Taking this anomaly as the stagnant slab and considering the plate convergence rate of 7–10 cm/year in the western Pacific region during the late Cenozoic, we deduced that the stagnant slab has a subduction age of less than 30 Ma. This suggests that the observed stagnancy of the slab in the MTZ beneath Northeast Asia may have occurred no earlier than the Early Oligocene. From the constraints derived individually on Vp and Vs structures, high Vp/Vs ratios are obtained for the entire MTZ beneath Northeast Asia, which may imply a water‐rich and/or carbonated environment. Within the overall higher‐velocity stagnant slab, a low‐velocity anomaly was further detected, with a width of ~150 km, Vp and Vs reductions of 1% and 3% relative to IASP91. Such a gap may have provided a passage for hot deep mantle materials to penetrate through the thick slab and feed the Changbaishan volcano.

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Section: 1029/2018jb016642supporting

confidence: 61%

Section: Construction Of the 2‐d Slab Modelmentioning

confidence: 79%

Mantle Transition Zone Structure Beneath Northeast Asia From 2‐D Triplicated Waveform Modeling: Implication for a Segmented Stagnant Slab

et al. 2019

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“…Moreover, models produced via tomographic methods may underestimate the strengths of such anomalies. For example, the velocity perturbations representative of slab‐like structures are generally smaller in tomographic images than in those inferred from recent waveform modeling endeavors (Zhan et al, ).…”

Section: Introductionmentioning

confidence: 99%

Lower Mantle Substructure Embedded in the Farallon Plate: The Hess Conjugate

Helmberger

Wang

et al. 2017

Geophysical Research Letters

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The morphologies of subducted remnants in the lower mantle are essential to our understanding of the history of plate tectonism. Here we image a high‐velocity slab‐like (HVSL) anomaly beneath the southeastern U.S. using waveforms from five deep earthquakes beneath South America recorded by the USArray. In addition to travel time anomalies, the multipathing of S and ScS phases at different distances are used to constrain the HVSL model. We jointly invert S and ScS traveltimes, amplitudes, and waveform complexities to produce a best fitting block model characterized by a rectangular shape with a 2.5% S wave velocity increase and tapered edges. While the Farallon slab is expected to dip primarily eastward, the HVSL structure apparently dips 40° to 50° to the SE and appears to be related to the eclogitized Hess conjugate.

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“…Thus, relatively steep ray paths (such as SKS) can be used to define local boundary sharpness and small features such as ULVZs using the SPdKS arrival. Defining the boundaries of the mid-Pacific LLSVP has been difficult using seismic tomographic methods (Text S2), especially considering uncertainty in event locations caused by slab structure (Lu & Grand, 2016;Zhan et al, 2014). In contrast, the LLVSP beneath the mid-Pacific is more difficult to define because of the few seismic stations available regionally.…”

Section: Introductionmentioning

confidence: 99%

“…The northeastern boundary of the mid-Pacific LLSVP beneath southeastern Hawaii has been extensively probed (Figure 1a), and many complexities have been revealed. Defining the boundaries of the mid-Pacific LLSVP has been difficult using seismic tomographic methods (Text S2), especially considering uncertainty in event locations caused by slab structure (Lu & Grand, 2016;Zhan et al, 2014). A more detailed discussion of the tomographic models can be found in Text S2 (Chu et al, 2017;Gaherty et al, 1996Gaherty et al, , 1999Lai et al, 2017;Ritsema et al, 2011;Simmons et al, 2012;Tan & Helmberger, 2007).…”

Section: Introductionmentioning

confidence: 99%

Slab Control on the Northeastern Edge of the Mid‐Pacific LLSVP Near Hawaii

Sun

Helmberger

Lai

et al. 2019

Geophysical Research Letters

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At the core‐mantle boundary, most observed ultralow velocity zones (ULVZs) cluster along the edges of the large low shear velocity provinces (LLSVPs) and provide key information on the composition, dynamics, and evolution of the lower mantle. However, their detailed structure near slab‐like structures beneath the mid‐Pacific remains particularly challenging because of the lack of station coverage. While most studies of ULVZs concentrate on SKS‐complexity, here we report on the multipathing of ScS, which expands the sampling for ULVZs. We find the strongest multipathing along a ULVZ patch located just south of Hawaii and the far northeastern edge of the LLSVP, in a zone ~200 km in width and extending 600 km southward. The anomalous ScS travel times and distorted Sdiff waveforms further reveal patches interrupted by observed enhanced D″ indicative of slab‐debris influence on the complexity of the northeastern boundary of the mid‐Pacific LLSVP.

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Imaging subducted slab structure beneath the Sea of Okhotsk with teleseismic waveforms

Cited by 24 publications

References 40 publications

Mantle Transition Zone Structure Beneath Northeast Asia From 2‐D Triplicated Waveform Modeling: Implication for a Segmented Stagnant Slab

Mantle Transition Zone Structure Beneath Northeast Asia From 2‐D Triplicated Waveform Modeling: Implication for a Segmented Stagnant Slab

Lower Mantle Substructure Embedded in the Farallon Plate: The Hess Conjugate

Slab Control on the Northeastern Edge of the Mid‐Pacific LLSVP Near Hawaii

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