Article
Geochemistry & Geophysics
Ping Tong, Tianjue Li, Jing Chen, Masaru Nagaso
Summary: The adjoint-state traveltime tomography (ATT) method offers an alternative approach to traveltime tomography without relying on ray tracing or waveform modeling. It uses the eikonal equation to describe the minimal traveltime field and formulates the inversion as an optimization problem. Two variants of the ATT method are derived for velocity structure and earthquake location determination. Numerical examples show that the ATT-CS method is useful for imaging receiver-side velocity structures, while the ATT-CR method is suitable for resolving source-side velocity structures.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Ole Edvard Aaker, Espen Birger Raknes, Orjan Pedersen, Borge Arntsen
Summary: Full waveform inversion (FWI) is a useful method for determining medium parameters by minimizing the difference between observed and modelled waves. However, the conventional FWI is limited in determining long-to-intermediate wavelength properties of the medium with transmitted waves. Reflection waveform inversion (RWI) utilizes reflected waves to retrieve these properties, and joint full waveform inversion (JFWI) combines both transmitted and reflected waves. An improvement to RWI and JFWI is proposed by using Newton methods to directly account for crosstalk between parameters, resulting in improved spatial focusing of search directions.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
S. L. E. F. da Silva, A. Karsou, A. de Souza, F. Capuzzo, F. Costa, R. Moreira, M. Cetale
Summary: The study introduces a new Wasserstein metric based on q-statistics for Full-waveform inversion (FWI) and proposes a q-GSOT-FWI strategy to address cycle skipping issues in conventional FWI approaches.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
P. T. C. Carvalho, S. L. E. F. da Silva, E. F. Duarte, R. Brossier, G. Corso, J. M. de Araujo
Summary: This article introduces a new objective function for full waveform inversion (FWI) that uses non-parametric kernel density estimation technique to explore a more suitable probability distribution. The proposed method shows lower sensitivity to adverse situations (such as cycle-skipping) and noise in observed data, leading to more accurate subsurface models.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Ryoichiro Agata, Amato Kasahara, Yuji Yagi
Summary: The uncertainty of underground structure significantly impacts fault slip estimation, and methods incorporating model prediction errors into Bayesian inference have been proposed. These methods can successfully extract slip distribution and underground structure information from data.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Da Li, Michael P. Lamoureux, Wenyuan Liao
Summary: This paper introduces several improvements to the Full Waveform Inversion (FWI) method and demonstrates them with numerical examples. The improvements include using an unbalanced optimal transport distance, constructing a mixed L1/Wasserstein distance, and utilizing entropy regularization and convolutional scaling algorithms to improve efficiency.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Anandaroop Ray
Summary: Geoscientists infer subsurface earth properties based on surface observations of electromagnetic or seismic data, with a focus on understanding spatial characteristics and length scales. These inferences rely on modeling techniques and optimization methods to simplify models, leading to insights into the underlying earth structure or physical phenomena. The use of non-stationary Gaussian Processes allows for a parametrization of earth properties and length scales in a framework that can accurately characterize subsurface properties.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Mohsen Kazemnia Kakhki, Ahmadreza Mokhtari, Webe Joao Mansur, Vincenzo Del Gaudio
Summary: In this paper, a novel time-frequency polarization filter based on three-component sparse adaptive S transform (3C-SAST) is proposed, which demonstrates high efficiency and flexibility in seismic surface wave separation.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Andreas Fichtner, Coen Hofstede
Summary: This paper presents a basic algorithm for optimal experimental design in distributed fibre-optic sensing. The algorithm takes into account various factors such as cable length, points of interest, obstacles, and topographic variations, allowing for flexibility in different applications.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
K. Nakai, T. Nagata, K. Yamada, Y. Saito, T. Nonomura, M. Kano, S. Ito, H. Nagao
Summary: In the near future, seismic research will utilize not only seismic data acquired by seismometers, but also data acquired by vibrometers in buildings and infrastructure, as well as accelerometers in smartphones. Selecting observation sites suitable for accurately estimating physical model parameters is essential. This study proposes a method based on process-driven approaches to select observation sites and accurately reconstruct the seismic wavefield.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Leon Diekmann, Ivan Vasconcelos, Tristan van Leeuwen
Summary: Full waveform inversion and least-squares reverse time migration are commonly used for seismic wave imaging, relying on the Born approximation to compute gradients and update models. We propose using the Marchenko integral to obtain an alternative linear equation that includes all orders of scattering. This new linearization strategy, although relying on the quality of the Marchenko-derived Green's functions, produces slightly better inverted models than the single-scattering approximation.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Huachen Yang, Jianzhong Zhang, Kai Ren, Changbo Wang
Summary: A non-iterative first-arrival traveltime inversion method (NFTI) is proposed for building smooth velocity models using seismic diving waves observed on irregular surface. The new equations and methods have been validated in tests, showing effectiveness and superiority, but also limitations in abrupt velocity model scenarios.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Engineering, Marine
Rubisel Perez-Castro, Francisco L. Silva-Gonzalez
Summary: Environmental contours are commonly used in the design of marine structures to identify extreme environmental conditions. This paper proposes a method to determine environmental contours using imprecise probability models, considering the uncertainties in the joint cumulative distribution function of the environmental variables. The proposed method incorporates probability boxes defined by confidence intervals and models the dependence structure using copulas. The method is applied to obtain imprecise environmental contours for a site in the Gulf of Mexico and determine the imprecise most probable extreme response of a tension leg platform.
Article
Geochemistry & Geophysics
Anandaroop Ray, Yusen Ley-Cooper, Ross C. Brodie, Richard Taylor, Neil Symington, Negin F. Moghaddam
Summary: Long-range, active-source airborne electromagnetic (AEM) systems for near-surface conductivity imaging are categorized into helicopter borne and fixed-wing aircraft borne. Various factors affect the geological resolvability, and test flights over well-constrained subsurface geology are useful for resolution studies. Handling transmitter-receiver geometries in fixed-wing aircraft is challenging due to the non-linearity of the electromagnetic inverse problem. Probabilistic inversions, using information theoretic attributes, can provide a comprehensive picture of the subsurface conductivity distributions for each kind of AEM system.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Mechanics
Saeed Tahir, Abdelbaki Chikh, Abdelouahed Tounsi, Mohammed A. Al-Osta, Salah U. Al-Dulaijan, Mesfer M. Al-Zahrani
Summary: This paper presents the wave propagation analysis of porous functionally graded sandwich plates in a hygro-thermal environment using a simple four-unknown integral higher-order shear deformation theory. It investigates the effects of moisture and temperature on wave propagation by considering their role on materials' expansion, and discusses the impact of various factors through numerical results. The findings can serve as a benchmark for further studies on wave propagation in functionally graded plates.
COMPOSITE STRUCTURES
(2021)
Article
Geochemistry & Geophysics
Anandaroop Ray, Sam Kaplan, John Washbourne, Uwe Albertin
GEOPHYSICAL JOURNAL INTERNATIONAL
(2018)
Article
Geochemistry & Geophysics
Daniel Blatter, Kerry Key, Anandaroop Ray, Neil Foley, Slawek Tulaczyk, Esben Auken
GEOPHYSICAL JOURNAL INTERNATIONAL
(2018)
Article
Geochemistry & Geophysics
Anandaroop Ray, Kerry Key
GEOPHYSICAL JOURNAL INTERNATIONAL
(2012)
Article
Geochemistry & Geophysics
Anandaroop Ray, Kerry Key, Thomas Bodin, David Myer, Steven Constable
GEOPHYSICAL JOURNAL INTERNATIONAL
(2014)
Article
Geochemistry & Geophysics
Anandaroop Ray, David L. Alumbaugh, Michael Hoversten, Kerry Key
Article
Geosciences, Multidisciplinary
Anandaroop Ray, Deepak C. Srivastava
JOURNAL OF STRUCTURAL GEOLOGY
(2008)
Article
Geosciences, Multidisciplinary
Andrew Cullen, Paul Reemst, Gijs Henstra, Simon Gozzard, Anandaroop Ray
PETROLEUM GEOSCIENCE
(2010)
Article
Geochemistry & Geophysics
Anandaroop Ray, David Myer
GEOPHYSICAL JOURNAL INTERNATIONAL
(2019)
Article
Geochemistry & Geophysics
Anandaroop Ray
Summary: Geoscientists infer subsurface earth properties based on surface observations of electromagnetic or seismic data, with a focus on understanding spatial characteristics and length scales. These inferences rely on modeling techniques and optimization methods to simplify models, leading to insights into the underlying earth structure or physical phenomena. The use of non-stationary Gaussian Processes allows for a parametrization of earth properties and length scales in a framework that can accurately characterize subsurface properties.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Daniel Blatter, Anandaroop Ray, Kerry Key
Summary: Bayesian inversion of electromagnetic data was used to infer subsurface resistivity with crucial uncertainty information. A fully 2-D, trans-dimensional Bayesian inversion of magnetotelluric (MT) data was successfully demonstrated for the first time in this study. The use of a Gaussian process algorithm allowed for a parsimonious parametrization of the model and made the computational cost tractable.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Multidisciplinary Sciences
Daniel Blatter, Samer Naif, Kerry Key, Anandaroop Ray
Summary: Using experimentally constrained parameterization of mantle melting and Bayesian resistivity inversion, the study suggests that a mantle plume injected volatile-rich melts into the LAB channel. This may be a significant source of anomalies in the Earth's interior globally.
Article
Geosciences, Multidisciplinary
Wenping Jiang, Ross C. Brodie, Jingming Duan, Ian Roach, Neil Symington, Anandaroop Ray, James Goodwin
Summary: We have developed a Bayesian inference algorithm and made the source code publicly available for the 1D inversion of audio-frequency magnetotelluric data. The algorithm uses a trans-dimensional Markov chain Monte Carlo technique to determine a probabilistic resistivity-depth model. This approach provides a comprehensive exploration of model space and offers a more robust estimation of uncertainty compared to deterministic methods.
JOURNAL OF APPLIED GEOPHYSICS
(2023)