Frequency-dependent shear wave splitting beneath the Japan and Izu-Bonin subduction zones

Wirth, Erin A.; Long, Maureen D.

doi:10.1016/j.pepi.2010.05.006

Cited by 71 publications

(90 citation statements)

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“…Any dependence on frequency can therefore be interpreted as evidence for complex anisotropic structure at depth (see also Saltzer et al 2000;Fouch and Rondenay 2006). Frequency dependent splitting has been identified in several regions, including New Zealand (Marson-Pidgeon and Savage 1997), Australia (Clitheroe and van der Hilst 1998), the Marianas , the Kaapvaal craton (Fouch et al 2004), and Japan (Long andvan der Hilst 2005b, 2006;Wirth and Long 2008); an example is illustrated in Fig. 7.…”

Section: Frequency Dependence Of Splitting Measurementsmentioning

confidence: 99%

“…Fig. 7 An example of strongly frequency-dependent splitting of local S phases from the data set of Wirth and Long (2008). a Individual splitting measurements using the crosscorrelation method are plotted at the midpoint between the event and station; data were filtered to retain energy at periods between 8 and 50 s. Bars are scaled to the delay time and the color indicates the delay time range:…”

Section: Small-scale Lateral Variationsmentioning

confidence: 99%

“…A transition from trench-parallel splitting close to the trench to trench-perpendicular further in the backarc has been observed in several regions (e.g., northern Honshu; Nakajima and Hasegawa 2004), but the opposite transition has been observed in a few regions, including Kamchatka . In some wedges, the spatial pattern of fast directions is extremely complicated, such as central Japan (Salah et al 2008;Wirth and Long 2008). As with the sub-slab case, the pattern that would be predicted for a simple corner flow model with A-type olivine fabric-dominantly trenchperpendicular fast directions-is virtually absent from the global database.…”

Section: Subduction Zonesmentioning

confidence: 99%

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Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

2009

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Measurements of the splitting or birefringence of seismic shear waves that have passed through the Earth's mantle yield constraints on the strength and geometry of elastic anisotropy in various regions, including the upper mantle, the transition zone, and the D 00 layer. In turn, information about the occurrence and character of seismic anisotropy allows us to make inferences about the style and geometry of mantle flow because anisotropy is a direct consequence of deformational processes. While shear wave splitting is an unambiguous indicator of anisotropy, the fact that it is typically a near-vertical path-integrated measurement means that splitting measurements generally lack depth resolution. Because shear wave splitting yields some of the most direct constraints we have on mantle flow, however, understanding how to make and interpret splitting measurements correctly and how to relate them properly to mantle flow is of paramount importance to the study of mantle dynamics. In this paper, we review the state of the art and recent developments in the measurement and interpretation of shear wave splitting-including new measurement methodologies and forward and inverse modeling techniques,-provide an overview of data sets from different tectonic settings, show how they help us relate mantle flow to surface tectonics, and discuss new directions that should help to advance the shear wave splitting field.

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Section: Frequency Dependence Of Splitting Measurementsmentioning

confidence: 99%

Section: Small-scale Lateral Variationsmentioning

confidence: 99%

Section: Subduction Zonesmentioning

confidence: 99%

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Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

2009

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“…V sub is the absolute velocity of the subducting plate, V t is the trench migration velocity, V up is the overriding plate velocity, V d is the deformation rate in the back-arc region, V c is the convergence velocity, a s is the shallow dip angle, and a d is the deep dip angle Earthq Sci (2016) 29(4):243-258 245 3 Seismic anisotropy data in subduction zones Schutt and Fouch (2001) and Wüstefeld et al (2009) collected and compiled seismic anisotropy data from different studies. Several researchers, including Wirth and Long (2010) and Liu et al (2008), also discussed the quality of the data in their studies. High-quality seismic anisotropy data generally have a high signal-to-noise ratio, a clear waveform, elliptical particle motion, and linear or nearly linear corrected particles.…”

Section: Subduction Zones and Dszsmentioning

confidence: 99%

“…Although the well-constrained estimates of dt can be obtained from seismogram records, the complex patterns of seismic anisotropy along a splitting ray path can result in very complicated shear wave (e.g., Silver and Savage 1994;Long 2013;Mohiuddin et al 2015). Additional complications arise as the splitting parameters are dependent on the frequency content of the shear wave (e.g., Wirth and Long 2010]. The propagation time for each segment of the splitting wave ray path is added to the total dt, which is probably the primary reason for inducing the relatively poor linear relationship between average dt and subduction angle a DSZ (Fig.…”

Section: Average Delay Time and Dszsmentioning

confidence: 99%

Lattice-Preferred orientations of olivine in subducting oceanic lithosphere derived from the observed seismic anisotropies in double seismic zones

Han

Zhang

et al. 2016

Earthq Sci

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Subduction zones can generally be classified into Mariana type and Chilean type depending on plate ages, plate thicknesses, subduction angles, back-arc deformation patterns, etc. The double seismic zones (DSZs) in subduction zones are mainly divided into type I and type II which, respectively, correspond to the Mariana type and Chilean type in most cases. Seismic anisotropy is an important parameter characterizing the geophysical features of the lithosphere, including the subduction zones, and can be described by the two parameters of delay time dt and fast wave polarization direction /. We totally collected 524 seismic anisotropy data records from 24 DSZs and analyzed the statistical correlations between seismic anisotropy and the related physical parameters of DSZs. Our statistical analysis demonstrated that the fast wave polarization directions are parallel to the trench strike with no more than 30°for most type I DSZs, while being nearly perpendicular to the trench strike for type II DSZs. We also calculated roughly linear correlations that the delay time dt increases with dip angles but decreases with subduction rates. A linear equation was summarized to describe the strong correlation between DSZ's subduction angle a DSZ and seismic anisotropy in subduction zones. These results suggest that the anisotropic structure of the subducting lithosphere can be described as a possible equivalent crystal similar to the olivine crystal with three mutually orthogonal polarization axes, of which the longest and the second axes are nearly along the trench-perpendicular and trench-parallel directions, respectively.

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Antigorite‐induced seismic anisotropy and implications for deformation in subduction zones and the Tibetan Plateau

Shao

Kondo

et al. 2014

JGR Solid Earth

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The present study, which is a follow-up of the Journal of Geophysical Research paper by Ji et al.(2013a), provides a new calibration for both seismic and fabric properties of antigorite serpentinites. Comparisons of the laboratory velocities of antigorite serpentinites measured at high pressures with crystallographic-preferred orientation data measured using electron backscatter diffraction techniques demonstrate that seismic anisotropy in high T serpentinite, which is essentially controlled by the antigorite c axis fabric, is independent on the operating slip system but strongly dependent on the regime and magnitude of finite strain experienced by the rock. Extrapolation of the experimental data with both pressure and temperature suggests that V p anisotropy decreases but shear wave splitting (ΔV s ) and V p /V s increase with increasing pressure in either cold or hot subduction zones. For a cold, steeply subducting slab, antigorite is most likely deformed by nearly coaxial flattening or trench-parallel movements, forming trench-parallel seismic anisotropy. For a hot, shallowly subducting slab, however, antigorite is most likely deformed by simple shear or transpression. Trench-normal seismic anisotropy can be observed when the subducting dip angle is smaller than 30°. The geophysical characteristics of the Tibetan Plateau such as strong heterogeneity in V p , V s and attenuation, shear wave splitting and electric conductivity may be explained by the presence of strongly deformed serpentinites in lithospheric shear zones reactivated along former suture zones between amalgamated blocks, hydrated zones of subducting lithospheric mantle, and the crust-mantle boundary if the temperature is below 700°C in the region of interest.

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Frequency-dependent shear wave splitting beneath the Japan and Izu-Bonin subduction zones

Cited by 71 publications

References 72 publications

Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

Lattice-Preferred orientations of olivine in subducting oceanic lithosphere derived from the observed seismic anisotropies in double seismic zones

Antigorite‐induced seismic anisotropy and implications for deformation in subduction zones and the Tibetan Plateau

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