Article
Geochemistry & Geophysics
A. Shaiban, S. A. L. de Ridder, A. Curtis
Summary: Surface waves are seismic waves that propagate on the Earth's surface and their depth ranges depend on frequency. By estimating the dispersion characteristics of these waves, the velocity structure beneath the surface can be inferred. Researchers have developed an inversion scheme that utilizes the scalar wave equation to estimate surface wave dispersion and reconstruct the wavefield continuously.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Hao Rao, Yinhe Luo, Kaifeng Zhao, Yingjie Yang
Summary: The study introduces an alternative method called the two-station C-2 method, which uses a single station as a virtual source to retrieve surface wave phase velocities between asynchronous stations. Results show that this method can obtain reliable phase velocity measurements and can significantly improve ray path coverage and resolution in ambient noise tomography for areas between asynchronous seismic arrays.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Chengyu Sun, Zhinong Wang, Dunshi Wu, Ruiqian Cai, Han Wu
Summary: This study derived dispersion curves of surface waves and guided waves using the transmission matrix method, and unified their characteristics through the relative amplitude dispersion map (RADM). Tests showed that RADM accurately reflects the dispersion energy of surface and guided waves, which is of great significance for inverting near-surface P and S wave velocities.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Lucia Gualtieri, Etienne Bachmann, Frederik J. Simons, Jeroen Tromp
Summary: Secondary microseisms are ambient noise vibrations caused by ocean activity and dominate seismic records worldwide at periods between 3 and 10 seconds. Using a spectral-element method for global-scale modeling, Love waves naturally emerge due to seismic wavefield interaction with Earth heterogeneity, particularly in the mantle. The distribution of surface sources, topography, and bathymetry are crucial for understanding the generation and propagation of Love waves in secondary microseisms.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Sergi Ventosa, Martin Schimmel
Summary: Seismic ambient noise has nonstationary time-frequency statistics, requiring better interstation correlation methods. The wavelet phase cross-correlation (WPCC) functions, incorporating ideas from the phase cross-correlation (PCC) method and wavelet cross-correlation, are introduced to analyze seismic ambient noise and extract clean broadband signals. WPCC has shown benefits in improving baseline corrections, signal extraction, and measurement accuracy compared to PCC. The use of GPU offsets the increase in computational cost, making WPCC an efficient approach for processing large data volumes in seismic interferometry studies.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2023)
Article
Geochemistry & Geophysics
Chaoqiang Xi, Jianghai Xia, Binbin Mi, Tianyu Dai, Ya Liu, Ling Ning
Summary: Ambient noise surface wave methods are valuable for determining near-surface shear wave velocities in urban areas, with higher mode information being important for dispersion curve inversion. The frequency-Bessel transform method is effective for multimode surface wave extraction, but may be affected by 'crossed' artefacts at high frequencies. The proposed modified F-J transform method, using the Hankel function, improves the accuracy of Rayleigh wave multimode dispersion measurements by avoiding these artefacts.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Zongbo Xu, Ludovic Margerin, T. Dylan Mikesell
Summary: Seismic coda waves are commonly used for estimating subsurface Q values and monitoring subsurface changes. A Monte Carlo algorithm is proposed to model the multiple scattering process and better understand the interaction between body and surface waves, which leads to accurate energy evolution in space and time.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Zongbo Xu, Ludovic Margerin, T. Dylan Mikesell
Summary: The study highlights the importance of the multiple scattering mechanism in coda waves for understanding subsurface Q values and monitoring subsurface changes. By using a Monte Carlo algorithm to simulate the interaction of these waves during multiple scattering, a more accurate physical modeling of the energy evolution of the waves can be achieved, improving the estimation of Q values and monitoring of coda wave changes.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Amsalu Anagaw, Mauricio D. Sacchi
Summary: Full waveform inversion (FWI) is a technique for estimating high-resolution physical properties of subsurface structures. This study proposes a regularization by denoising (RED) method to solve the FWI problem in high-contrast media. The RED algorithm is simple to implement and allows for easy parameter selection.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Chendong Zhang, Ting Chen
Summary: This study applies variational inference method to Bayesian slip inversion and compares it with classic Metropolis-Hastings sampling method. Synthetic test shows similar results between the two methods, while in real case study, ADVI method has lower computational cost but produces different standard deviation map.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Jianbo Guan, Yu Li, Yingwei Yan, Zhi Yang, Guohua Liu
Summary: This study introduces a novel approach for linear array analysis of passive surface waves combined with the Mini-Sosie technique, called LAPSS. Through synthetic tests, the results show that LAPSS greatly improves the computational efficiency, has stronger generalizability, and depends on weaker assumptions.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Enjiang Wang, Jose M. Carcione, Jing Ba
Summary: This study investigates the surface-wave propagations at the interface between a fluid layer and a double-porosity medium with cracks. The Biot-Rayleigh model is generalized to include penny-shaped cracks, and the role of mesoscopic local fluid flow (LFF) is considered. Dispersion equations for surface waves are derived, and numerical iterations are used to obtain phase velocity and attenuation. Different cases are analyzed for zero and infinite thickness of the fluid layer. The study confirms the effects of LFF at low frequencies and the impact of boundary conditions at high frequencies. The crack density affects the level of attenuation, while the aspect ratio affects the location of the relaxation peak.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Caiwang Shi, Hengxin Ren, Zhengbo Li, Xiaofei Chen
Summary: This paper proposes a semi-analytical spectral element method (SASEM) to calculate the normal and leaky modes of elastic waves propagating in a stratified model. The method is validated through numerical tests and applied to a vertically inhomogeneous offshore model. The analysis shows differences between leaky modes and normal modes due to the increasing wavefields in the half-space. The effective calculation of leaky modes allows for constraining the P-wave velocity using leaky-mode dispersion curves.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Jeremy M. Gosselin, Pascal Audet, Andrew J. Schaeffer, Fiona A. Darbyshire, Clement Esteve
Summary: Surface wave tomography is a valuable tool for constraining azimuthal anisotropy at regional scales, but the sparse and uneven coverage of dispersion measurements pose challenges in uncertainty estimation. A Bayesian trans-dimensional inversion approach is used in this paper to better model azimuthal anisotropy using surface wave dispersion data, with a focus on considering data errors and avoiding subjective model regularization. The results provide insights into the structural context of tectonic dynamics in northern Cascadia and Haida Gwaii, highlighting the importance of considering azimuthal anisotropy in tomographic inversions for understanding seismic and tsunami hazards.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Harriet C. P. Lau, David Al-Attar
Summary: The study efficiently calculates the linearized sensitivity of body tide observations to perturbations in density, elastic/anelastic moduli and boundary topography using the adjoint method. It demonstrates a strong sensitivity of the M2 body tide to spherical harmonic degree-2 density variations at the base of the mantle. The results show that the sensitivity kernels are weakly dependent on the background model, indicating that linearized methods are likely to be effective within inversions of body tide observations.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Yongxin Gao, Peng Jiang, Yixian Xu, Li Jiang, Chieh-Hung Cheng, Guoze Zhao, Ji Tang, Xiaobin Chen, Bin Han, Jiajun Chong, Cheng Yao
Summary: This study presents a method to numerically calculate the rotational motion and rotation-induced magnetic fields (RIMFs) excited by seismic waves in a horizontally layered model, allowing for analysis of magnetic disturbances during earthquake events. Numerical examples show varying characteristics of magnetic fields under different source excitations. Applying this method to the 2017 Jiuzhaigou earthquake successfully explains observed data, indicating that coseismic magnetic fields during this event are mainly due to magnetometer rotation.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Yi Zhang, Yixian Xu, Bo Yang
Summary: The L-GD algorithm is a stochastic optimization method based on Levy flights and gradient descending, showcasing faster search speed and higher efficiency compared to Brownian walks.
SURVEYS IN GEOPHYSICS
(2021)
Article
Geochemistry & Geophysics
Yi Zhang, Yixian Xu, Walter D. Mooney, Chao Chen
Summary: The paper introduces a new method for separating localized anomalies using equivalent source technique and iterative inversion process. The proposed method is verified with synthetic examples and applied to construct a 3-D model of mantle uplift beneath the Von Karman crater on the Moon. Investigating the deep crustal structure of the VKC provides insights into the evolutionary history of the region.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Shuyu Liu, Yixian Xu, Bo Yang, Zeqiu Guo, Yuan Shi, Ying Liu
Summary: The study proposes a strategy based on equivalent resistivity to recover fine resistivity structures from MT data in the lower crust. By defining the equivalent resistivity in a 3-D laminated structure, analyzing the electrical properties in the crust and the cause of lamellae can be successfully achieved.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geology
Y. X. Xu, B. Yang, S. C. Wu, Y. Shi, X. W. Bao, Y. Liu, Y. Zhang, Y. J. Yang, Q. Y. Wang, Q. K. Xia
Summary: Geophysical observations of the Baogutu porphyry copper-gold deposit and the Hatu epithermal gold deposit in the late Paleozoic arc in the western Junggar, NW China, revealed the control mechanism of metal preconcentration by the deep crust, which is crucial for the formation of mineral deposits.
ORE GEOLOGY REVIEWS
(2021)
Article
Geochemistry & Geophysics
Chieh-Hung Chen, Yang-Yi Sun, Kai Lin, Chen Zhou, Rui Xu, Haiyin Qing, Yongxin Gao, Tao Chen, Fei Wang, Huaizhong Yu, Peng Han, Chi-Chia Tang, Xiaoning Su, Xuemin Zhang, Linguo Yuan, Yixian Xu, Jann-Yenq Liu, Shunkuan Yu
Summary: A novel system called MVP-LAI was established in rural Leshan City, China, to monitor vibrations and perturbations in the coupling between the lithosphere, atmosphere, and ionosphere (LAI). This system uses multiple instruments to track changes in geophysical parameters and investigate the causal mechanisms of LAI coupling, contributing to research on potential sources of vibrations and perturbations and incorporating observations from other spheres.
SURVEYS IN GEOPHYSICS
(2021)
Article
Geochemistry & Geophysics
Yi Zhang, Yixian Xu, Bo Yang, Walter D. Mooney, Feng Wang
Summary: This study proposes algorithms for constructing smoothness and structural similarity operators to improve the regularization of geophysical inversions on unstructured meshes, leading to better and more stable results.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geosciences, Multidisciplinary
Yingkai Wu, Xuewei Bao, Bingfeng Zhang, Yixian Xu, Wencai Yang
Summary: By stacking receiver functions, the structure of the mantle transition zone beneath western Tibet and Himalaya has been imaged, revealing evidence of the detached Lhasa lithospheric mantle and recently delaminated Qiangtang lithosphere in the study area. The small dependence of d410 amplitude on frequency indicates the anhydrous nature of the MTZ.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Yixian Xu, Yi Zhang, Bo Yang, Xuewei Bao
Summary: This study presents a method to reconstruct the Paleozoic-lithospheric structures of the North China Craton (NCC) and reveals that there was massive thinning in the eastern East Block (EB) after the Paleozoic, while thickening occurred in the northern Ordos Basin and the region from the Weibei uplift to the South Taihang Mountains uplift. The calculated self-sustaining oscillation periods are in good agreement with the periodicity observed in the sedimentation rate of the Ordos Basin and basaltic underplating events in the Trans-North China Orogen. The results suggest that, apart from the EB, the Phanerozoic lithospheric modification of the NCC is mainly controlled by heat conduction and dissipation through the cratonic lithosphere.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Kai He, Rong Huang, Yixian Xu, Shaoqian Hu, Penglong Wei
Summary: Based on recordings from 42 seismic stations, we determined the sediment and crustal thickness in the Northern Jiangsu Basin and proposed a method to correct the depth of the Moho discontinuity using sediment thickness. Our findings reveal thin sediment in the northwest of the basin and suggest extending the southeastern border. The variations in the Moho indicate remnants of shearing movements since the Miocene. Additionally, we identify the Gaoyou area as a prospective location for geothermal exploration.
JOURNAL OF GEOPHYSICS AND ENGINEERING
(2022)
Article
Geochemistry & Geophysics
Rong Huang, Lupei Zhu, Yixian Xu, Chi-Chia Tang, Hongbin Wen
Summary: Seismic activity in the Three Gorges Reservoir region has increased due to the rising water level caused by the construction of the Three Gorges Dam in 2003. By analyzing seismic waveform data, we determined the moment tensors and focal depths of six earthquakes in the 2014 Zigui earthquake sequence. The results suggest that these earthquakes were not directly induced by the reservoir water, but triggered by the stress change from the annual reservoir water level variation. The newly discovered fault in the region has the potential to cause a magnitude 5.7 earthquake.
SEISMOLOGICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Yuan Shi, Yixian Xu, Bo Yang, Shuyu Liu
Summary: The study finds that the conductors in different regions of the North China Craton can be attributed to different tectonic mechanisms, including oceanic subduction, ancient suture zones, and modern craton destruction. In addition, anisotropy is observed in the lower crust and uppermost mantle of the southern part of the North China Plain, with enhanced conductivity along a specific direction, which may be related to magma accumulation caused by Cenozoic asthenosphere upwelling.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Binbin Mi, Jianghai Xia, Yixian Xu, Baiyang You, Yunfeng Chen
Summary: Train traffic has been identified as a potential seismic source for imaging and monitoring shallow subsurface structures. This study focuses on the seismic wavefields generated by high-speed trains on viaducts. It is found that these sources exhibit self-correlation and produce time-delayed spurious signals in the crosscorrelation functions. The study proposes a direct-wave interferometry method that can reduce the spurious imprint of source self-correlations. Synthetic and field data experiments demonstrate the effectiveness of the proposed scheme for imaging and monitoring the shallow subsurface.
Article
Multidisciplinary Sciences
Bingfeng Zhang, Xuewei Bao, Yingkai Wu, Yixian Xu, Wencai Yang
Summary: Syncontractional extension in present-day Tibet is linked to the underthrusting Indian plate, which exerts strong north-directed shearing and enables the extension in southern Tibet. Seismic anisotropy measurements reveal the convergence-parallel alignment of anisotropic fabrics in the deep crust of the southern Tibetan rifts, shedding light on the cause of syncontractional extension in the region.
NATURE COMMUNICATIONS
(2023)
Article
Computer Science, Interdisciplinary Applications
Zhong Peng, Bo Yang, Lian Liu, Yixian Xu
Summary: The magnetotelluric (MT) forward modeling problem is computationally slow due to the large scale of the algebraic system solving process. To improve efficiency, a physics-driven model (PDM) using deep neural networks (DNNs) as a surrogate is proposed. The PDM shows excellent agreement with the finite-difference method (FDM) in predicting MT responses and has a much faster computing speed.
COMPUTERS & GEOSCIENCES
(2023)
