Structure of the crust beneath the southeastern Tibetan Plateau from teleseismic receiver functions

Xu, Lili; Rondenay, S.; Hilst, Robert D. van der

doi:10.1016/j.pepi.2007.09.002

Cited by 238 publications

(236 citation statements)

References 67 publications

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“…It is important to mention that the results obtained by Wang et al (2007) and Xu et al (2007) show a smooth 2D variation of the V P , V S , and density values found for the region included in Figure 1 and Figure 3. Those values reflect the properties of the layers forming the topography of the Sichuan region shown in these two figures; for example, the recording station sites MC03 (∼15 km of the Longmen Shan fault system) and MC04 of figure 10 of Xu et al (2007), located at altitudes of 2 and 4 km, respectively.…”

Section: Geotectonic Characteristics Of the Region Around The Longmenmentioning

confidence: 70%

“…Among other results, they obtained the V S crustal velocities up to a depth of 80 km for profiles that included some station sites located in the vicinity of the Longmen Shan fault system. Of particular interest for this work is the result shown in figure 10 of Xu et al (2007): in the first 7 km of depth; the V S values are significantly inferior to 3 km=s. Xu et al (2007) also proposed ratios of V P =V S for the mentioned station sites, which, on average are equal to 1:86 0:07.…”

Section: Geotectonic Characteristics Of the Region Around The Longmenmentioning

confidence: 96%

“…The velocity-stress form of the elastic wave equation consists of nine coupled, first-order partial differential equations for the three particle velocity vector components ν ij x; t and the six independent stress tensor components, σ ij x; t, where i, j 1, 2, 3, and assuming that σ ij x; t σ ji x; t: Table 1). AA′ and BB′ correspond to the seismic profiles studied by Wang et al, (2007); CC′, DD′, and EE′ identify the seismic profiles studied by Xu et al, (2007). The surface projection of the rupture area of the 12 May 2008 M w 7.9 Wenchuan earthquake is represented by the long rectangle, and its inner rectangles identify the areas with kinematic slips > 6 to 9 m suggested by Ji and Hayes (2008).…”

Section: Elastodynamic Formulation Of the Elastic Wave Propagation Prmentioning

confidence: 96%

“…1) was obtained by Xu et al (2007). They applied the receiver function technique to very broadband (VBB) recordings of teleseismic earthquakes in 25 temporal stations, disseminated in the Sichuan region at altitudes from 0 (on the Sichuan basin) to 4 km (on the western Sichuan Plateau); see Figure 1.…”

Section: Geotectonic Characteristics Of the Region Around The Longmenmentioning

confidence: 99%

See 3 more Smart Citations

Low-Frequency 3D Wave Propagation Modeling of the 12 May 2008 Mw 7.9 Wenchuan Earthquake

Chávez¹,

Cabrera²,

Madariaga³

et al. 2010

Bulletin of the Seismological Society of America

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The seismic potential of southern China is associated with the collision between the Indian and the Eurasian plates. This is manifested in the western Sichuan Plateau by several seismically active systems of faults, such as the Longmen Shan. The seismicity observed on the Longmen Shan fault includes recent events with magnitudes of up to 6.5, and the one of 12 May 2008 M w 7.9 Wenchuan earthquake. Herewith, as part of an ongoing research program, a recently optimized threedimensional (3D) seismic wave propagation parallel finite-difference code was used to obtain low-frequency (≤ 0:3 Hz) 3D synthetic seismograms for the Wenchuan earthquake. The code was run on KanBalam (Universidad Nacional Autónoma de México, Mexico) and HECToR (UK National Supercomputing Service) supercomputers. The modeling included the U.S. Geological Survey 40 × 315 km 2 kinematic description of the earthquake's rupture, embedded in a 2400 × 1600 × 300 km 3 physical domain, spatially discretized at 1 km in the three directions and a temporal discretization of 0.03 s. The compression and shear wave velocities and densities of the geologic structure used were obtained from recently published geophysical studies performed in the Sichuan region. The synthetic seismograms favorably compare with the observed ones for several station sites of the Seismological and Accelerographic Networks of China, such as MZQ, GYA, and TIY, located at about 90, 500, and 1200 km, respectively, from the epicenter of the Wenchuan event. Moreover, the comparisons of synthetic displacements with differential radar interferometry (DinSAR) ground deformation imagery, as well as of maximum velocity synthetic patterns with Mercalli modified intensity isoseist of the 2008 Wenchuan earthquake, are acceptable. 3D visualizations of the propagation of the event were also obtained; they show the source rupture directivity effects of the M w 7.9 Wenchuan event. Our results partially explain the extensive damage observed on the infrastructure and towns located in the neighborhood of the Wenchuan earthquake rupture zone.

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Section: Geotectonic Characteristics Of the Region Around The Longmenmentioning

confidence: 70%

Section: Geotectonic Characteristics Of the Region Around The Longmenmentioning

confidence: 96%

Section: Elastodynamic Formulation Of the Elastic Wave Propagation Prmentioning

confidence: 96%

Section: Geotectonic Characteristics Of the Region Around The Longmenmentioning

confidence: 99%

See 2 more Smart Citations

Low-Frequency 3D Wave Propagation Modeling of the 12 May 2008 Mw 7.9 Wenchuan Earthquake

Chávez¹,

Cabrera²,

Madariaga³

et al. 2010

Bulletin of the Seismological Society of America

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show abstract

“…3a) is used to invert for the isotropic shear wavespeed model (with vp and density related to vs) using the NA following the procedure by Yao et al (2008). Here the Moho depth is fixed in the inversion with its value (54 km) approximately inferred from the receiver function analysis by Xu et al (2007). We have eight parameters to be estimated, that is, shear wavespeed perturbations of the three crustal layers and five upper mantle layers with respect to a reference model.…”

Section: Inversion For Shear Wavespeeds and Azimuthal Anisotropymentioning

confidence: 99%

A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

Yao

2015

Earthq Sci

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Seismic anisotropy provides important constraints on deformation patterns of Earth's material. Rayleigh wave dispersion data with azimuthal anisotropy can be used to invert for depth-dependent shear wavespeed azimuthal anisotropy, therefore reflecting depth-varying deformation patterns in the crust and upper mantle. In this study, we propose a two-step method that uses the Neighborhood Algorithm (NA) for the point-wise inversion of depth-dependent shear wavespeeds and azimuthal anisotropy from Rayleigh wave azimuthally anisotropic dispersion data. The first step employs the NA to estimate depthdependent V SV (or the elastic parameter L) as well as their uncertainties from the isotropic part Rayleigh wave dispersion data. In the second step, we first adopt a difference scheme to compute approximate Rayleigh-wave phase velocity sensitivity kernels to azimuthally anisotropic parameters with respect to the velocity model obtained in the first step. Then we perform the NA to estimate the azimuthally anisotropic parameters G c /L and G s /L at depths separately from the corresponding cosine and sine terms of the azimuthally anisotropic dispersion data. Finally, we compute the depth-dependent magnitude and fast polarization azimuth of shear wavespeed azimuthal anisotropy. The use of the global search NA and Bayesian analysis allows for more reliable estimates of depth-dependent shear wavespeeds and azimuthal anisotropy as well as their uncertainties.We illustrate the inversion method using the azimuthally anisotropic dispersion data in SE Tibet, where we find apparent changes of fast axes of shear wavespeed azimuthal anisotropy between the crust and uppermost mantle.

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Constraining melt geometries beneath the Afar Depression, Ethiopia from teleseismic receiver functions: The anisotropic H‐κstacking technique

Hammond

2014

Geochem. Geophys. Geosyst.

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Understanding the nature of the crust has long been a goal for seismologists when imaging the Earth. This is particularly true in volcanic regions where imaging melt storage and migration can have important implications for the size and nature of an eruption. Receiver functions and the H-j stacking (Hj) technique are often used to constrain crustal thickness (H) and the ratio of P to S wave velocities (j). In this paper, I show that it is essential to consider anisotropy when performing Hj. I show that in a medium with horizontally transverse isotropy a strong variation in j with back azimuth is present, which characterizes the anisotropic medium. In a vertically transverse isotropic medium, no variation in j with back azimuth is observed, but j is increased across all back azimuths. Thus, estimates of j are more difficult to relate to composition than previously thought. I extend these models to melt-induced anisotropy and show that similar patterns are observed, but with more significant variations and increases in j. Based on these observations, I develop a new anisotropic H-j stacking technique which inverts Hj data for melt fraction, aspect ratio, and orientation of melt inclusions. I apply this to data for the Afar Depression and show that melt is stored in interconnected stacked sills in the lower crust, which likely supply the recent volcanic eruptions and dike intrusions. This new technique can be applied to any anisotropic medium where it can provide constraints on the average crustal anisotropy.

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Structure of the crust beneath the southeastern Tibetan Plateau from teleseismic receiver functions

Cited by 238 publications

References 67 publications

Low-Frequency 3D Wave Propagation Modeling of the 12 May 2008 Mw 7.9 Wenchuan Earthquake

Low-Frequency 3D Wave Propagation Modeling of the 12 May 2008 Mw 7.9 Wenchuan Earthquake

A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

Constraining melt geometries beneath the Afar Depression, Ethiopia from teleseismic receiver functions: The anisotropic H‐κstacking technique

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