Guided wave phase velocity measurement using multi-emitter and multi-receiver arrays in the axial transmission configuration

ABSTRACT An understanding of mantle dynamics occurring beneath the Tibetan plateau requires a detailed image of its seismic velocity and anisotropic structure. Surface waves at long periods (>50 s) could provide such critical information. Though Rayleigh-wave phase velocity maps have been constructed in the Tibetan regions using ambient-noise tomography (ANT) and regional earthquake surface-wave tomography, Love-wave phase velocity maps, especially those at longer periods (>50 s), are rare. In this study, two-plane-wave teleseismic surface-wave tomography is applied to develop 2D Rayleigh-wave and Love-wave phase velocity maps at periods between 20 and 143 s across eastern and central Tibet and its surroundings using four temporary broadband seismic experiments. These phase velocity maps share similar patterns and show high consistency with those previously obtained from ANT at overlapping periods (20–50 s), whereas our phase velocity maps carry useful information at longer periods (50–143 s). Prominent slow velocity is imaged at periods of 20–143 s beneath the interior of the Tibetan plateau (i.e., the Songpan–Ganzi terrane, the Qiangtang terrane, and the Lhasa terrane), implying the existence of thick Tibetan crust along with warm and weak Tibetan lithosphere. In contrast, the dispersal of fast velocity anomalies coincides with mechanically strong, cold tectonic blocks, such as the Sichuan basin and the Qaidam basin. These phase velocity maps could be used to construct 3D shear-wave velocity and radial seismic anisotropy models of the crust and upper mantle down to 250 km across the eastern and central Tibetan plateau.

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Surface-wave phase-velocity maps of the Anatolia region (Turkey) from ambient noise tomography

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2020.104322 ◽

2020 ◽

Vol 193 ◽

pp. 104322 ◽

Cited By ~ 2

Author(s):

C.P. Legendre ◽

T.L. Tseng ◽

L. Zhao

Keyword(s):

Surface Wave ◽

Phase Velocity ◽

Ambient Noise ◽

Ambient Noise Tomography ◽

Wave Phase ◽

Wave Phase Velocity

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Optical guiding and beat wave phase velocity control in the plasma beat wave accelerator

10.1063/1.38755 ◽

1989 ◽

Cited By ~ 3

Author(s):

E. Esarey ◽

A. Ting ◽

P. Sprangle

Keyword(s):

Phase Velocity ◽

Velocity Control ◽

Wave Phase ◽

Wave Phase Velocity

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Estimations of formation velocity, permeability, and shear‐wave anisotropy using acoustic logs

Geophysics ◽

10.1190/1.1443971 ◽

1996 ◽

Vol 61 (2) ◽

pp. 437-443 ◽

Cited By ~ 2

Author(s):

Ningya Cheng ◽

Chuen Hon Cheng

Keyword(s):

Phase Velocity ◽

Shear Wave ◽

Wave Velocity ◽

Shear Wave Velocity ◽

Stoneley Wave ◽

S Wave ◽

Acoustic Logging ◽

Wave Phase ◽

Wave Phase Velocity ◽

Logging Tool

Field data sets collected by an array monopole acoustic logging tool and a shear wave logging tool are processed and interpreted. The P‐ and S‐wave velocities of the formation are determined by threshold detection with cross‐correlation correction from the full waveform and the shear‐wave log, respectively. The array monopole acoustic logging data are also processed using the extended Prony’s method to estimate the borehole Stoneley wave phase velocity and attenuation as a function of frequency. The well formation between depths of 2950 and 3150 ft (899 and 960 m) can be described as an isotropic elastic medium. The inverted [Formula: see text] from the Stoneley wave phase velocity is in excellent agreement with the shear‐wave log results in this section. The well formation between the depths of 3715 and 3780 ft (1132 and 1152 m) can be described as a porous medium with shear‐wave velocity anisotropy about 10% to 20% and with the symmetry axis perpendicular to the borehole axis. The disagreement between the shear‐wave velocity from the Stoneley wave inversion and the direct shear‐wave log velocity in this section is beyond the errors in the measurements. Estimated permeabilities from low‐frequency Stoneley wave velocity and attenuation data are in good agreement with the core measurements. Also it is proven that the formation permeability is not the cause of the discrepancy. From the estimated “shear/pseudo‐Rayleigh” phase velocities in the array monopole log and the 3-D finite‐difference synthetics in the anisotropic formation, the discrepancy can best be explained as shear‐wave anisotropy.

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