Article
Chemistry, Multidisciplinary
Mohammed Fathy Gouda, Abdul Halim Abdul Latiff, Seyed Yasser Moussavi Alashloo
Summary: This study estimates zero-offset acoustic and shear impedances using statistical modeling and a multilayer feed-forward neural network (MLFN), and compares the results with those obtained from isotropic inversion and statistical modeling. The MLFN shows better matching with the impedance and facies logs.
APPLIED SCIENCES-BASEL
(2022)
Article
Geochemistry & Geophysics
Quan Liang, Wei Ouyang, Weijian Mao, Shijun Cheng, Xuelei Li
Summary: In this paper, a new method is proposed to address the challenging problem of high-precision inversion of acoustic wave data in complex anisotropic media. By using an appropriate parameterization and scattering integral method, the estimation of anisotropic parameters can be effectively achieved.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Geochemistry & Geophysics
Jincheng Xu, Jianfeng Zhang
Summary: An accurate migration velocity model is crucial for seismic imaging. The conventional methods for obtaining the velocity model are laborious and computationally expensive. To address these issues, a more effective migration velocity analysis method based on cross-correlation stacked time shift functions is proposed. This method uses a global optimization algorithm and incorporates prior information to improve accuracy and convergence speed.
GEOPHYSICAL PROSPECTING
(2023)
Article
Geology
Zhongmin Tao, Aibing Li, Karen M. Fischer
Summary: The presence of localized low-velocity anomalies in the upper mantle beneath the passive Atlantic margin in North America is a puzzling geophysical observation. The anomalies may be caused by the remnant heat from past hotspots or ongoing asthenospheric upwelling. Based on a recent velocity model, new information on the shapes and anisotropic signatures of these anomalies has been revealed, showing that the anomalies are likely consequences of prior hotspot interactions.
Article
Geosciences, Multidisciplinary
Zhonghan Liu, Yingcai Zheng, Hua-Wei Zhou
Summary: This study proposes and tests a new Direct Waveform Inversion (DWI) scheme for simultaneously inverting for subsurface layered velocity and density profiles. The scheme is implemented in the time-space domain and recursively determines the seismic structure layer by layer by explicitly enforcing the wavefield time-space causality.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Engineering, Geological
Md Mizanur Rahman, Yannis F. Dafalias
Summary: This study discusses the effects of fabric anisotropy and fines content on the mechanical behavior of sands, and develops the Anisotropic Critical State Theory and Equivalent Granular State Theory for clean sands. By combining these two theories, a constitutive model is proposed to simultaneously consider the effects of fabric anisotropy and fines content on the undrained response of sands.
Article
Geosciences, Multidisciplinary
Claudia Finger, Marco P. Roth, Marco Dietl, Aileen Gotowik, Nina Engels, Rebecca M. Harrington, Brigitte Knapmeyer-Endrun, Klaus Reicherter, Thomas Oswald, Thomas Reinsch, Erik H. Saenger
Summary: Passive seismic analyses are crucial for exploring and monitoring subsurface reservoirs. The Lower Rhine Embayment in Germany has a high potential for geothermal exploitation and experiences continuous natural seismicity. We present a passive seismic dataset recorded at Eschweiler-Weisweiler, showing that the network design allows for state-of-the-art analysis methods.
EARTH SYSTEM SCIENCE DATA
(2023)
Article
Geochemistry & Geophysics
Honggeun Jo, Yongchae Cho, Michael Pyrcz, Hewei Tang, Pengcheng Fu
Summary: Estimating porosity models from seismic data is challenging due to low signal-to-noise ratio and insufficient resolution. In this paper, a machine learning-based workflow is proposed to convert seismic data into porosity models. The workflow uses a residual U-Net++ architecture to estimate porosity models from multiple poststack seismic volumes. Experimental results show that the method achieves high accuracy and robustness in porosity estimation, but further research and improvements are needed.
Article
Geochemistry & Geophysics
Zhengtao He, Yuyong Yang, Huailai Zhou
Summary: Shear-wave splitting (SWS) analysis is used to predict fractures in subsurface media. New algorithms using gradient descent, Newton, and advance-retreat methods were proposed to improve the efficiency of SWS analysis. Among these methods, the gradient-descent method obtained the most accurate results.
Article
Geochemistry & Geophysics
T. Kimura, H. Mikada, E. Araki, S. Kodaira, S. Miura, N. Takahashi
Summary: This study analyzed the spatial variation of azimuthal S-wave phase velocity anisotropies in the Nankai Trough region to understand the stress state of the forearc region. Results showed that the polarization orientations of fast S-wave velocities are parallel to the convergent direction of the subducting plate in the deeper accretionary prism and perpendicular to the convergent direction in the shallow sediments.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Computer Science, Software Engineering
Joseph G. G. Wallwork, Nicolas Barral, David A. A. Ham, Matthew D. Piggott
Summary: This paper applies metric-based mesh adaptation methods to advection-dominated tracer transport modelling problems in two and three dimensions, achieving better approximations to the diagnostic quantity of interest (QoI) through goal-oriented mesh adaptation.
COMPUTER-AIDED DESIGN
(2022)
Article
Environmental Sciences
Hong Liu, Kunde Yang, Qiulong Yang
Summary: The adaptive particle filter method for sequential geoacoustic estimation in shallow water acoustic environments using explosive sound sources has been shown to be effective. This approach treats environmental parameters and source-receiver distance as evolving random variables. Compared to traditional particle filters, this method is more adaptable and accurate in estimating geoacoustic parameters and source-receiver distance.
Article
Geochemistry & Geophysics
S. Noe, S. Yuan, J-P Montagner, H. Igel
Summary: This study explores the potential of multicomponent, single-point ground-motion observations in estimating near-receiver anisotropic elastic parameters. Through analysis, it is found that in anisotropic media, wave propagation direction and velocities can be determined from multiple components of displacements and rotations, and a inverse problem is formulated to estimate the full elastic tensor from multidirectional observations, indicating the benefits of observing additional longitudinal strain components in the presence of noise.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geology
Keith Priestley, Tak Ho, Dan McKenzie
Summary: New evidence from seismic tomography indicates a unique mineral fabric in the thick mantle lithosphere beneath ancient continental cratons, shedding light on the formation of these structures. This mineral fabric, revealed through surface-wave tomography, suggests a vertical alignment of olivine crystals at depths of -150 km within cratonic continental-lithosphere roots, likely a remnant from craton formation. Geochemical and petrological studies further support the stability of cratonic mantle roots due to reduced density caused by melt removal at shallower depths. This seismological fabric at -150 km provides evidence of the shortening event that created the cratonic roots.
Article
Geosciences, Multidisciplinary
Yi Yang, Xiaodong Song
Summary: Analysis of repeated seismic waves since the early 1990s indicates that the rotation of Earth's inner core has recently paused and is now reversing, aligning with the multidecadal oscillation of the length of day and magnetic field variations. These findings provide evidence for dynamic interactions between different layers of the Earth, possibly due to the exchange of angular momentum from the core and mantle to the surface.