Article
Geosciences, Multidisciplinary
Dan Bassett, Gou Fujie, Shuichi Kodaira, Ryuta Arai, Yojiro Yamamoto, Stuart Henrys, Dan Barker, Andrew Gase, Harm Van Avendonk, Nathan Bangs, Hannu Seebeck, Brook Tozer, Katie Jacobs, Thomas Luckie, David Okaya, Kimi Mochizuki
Summary: Marine seismic data reveals the distribution of seamounts, sediment cover sequence, and crustal structure along the Hikurangi Plateau. Gravity data suggest that the variation in crustal thickness may be related to deformation and lithospheric extension. The variability in crustal thickness plays a significant role in plate boundary configuration and stress distribution.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
Yongchae Cho, Carlos Perez Solano, John Kimbro, Yi Yang, Rene-Edouard Plessix, Kenneth Matson
Summary: Elastic full-waveform inversion is crucial in building velocity models, especially in areas with large salt bodies. It helps reduce artifacts caused by using acoustic approximation, but defining the initial shear velocity model remains challenging. By utilizing reflected converted waves from the top of salt interface, we can improve the estimation of background shear velocity, and combining wave-equation traveltime inversion with FWI yields higher-resolution results.
Article
Geochemistry & Geophysics
Jian Sun, Kristopher Innanen, Tianze Zhang, Daniel Trad
Summary: Full waveform inversion (FWI) is a state-of-the-art method for imaging subsurface structures and physical parameters with seismic data, but it faces challenges in implementation and use. The implicit full waveform inversion (IFWI) algorithm, designed with deep neural representations, shows improved convergence and the ability to capture high-resolution subsurface structures. Although uncertainty analysis is not fully solved, IFWI addresses it meaningfully by approximating Bayesian inference. Numerical experimentation suggests that IFWI has a strong capacity for generalization and is suitable for multi-scale joint geophysical inversion.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
Zeyu Zhao, Mrinal K. Sen, Bertrand Denel, Dong Sun, Paul Williamson
Summary: A hybrid optimization framework is proposed for full waveform inversion (FWI) problems, which incorporates derivative information into the model update rule and improves the convergence speed to tackle the local minima issue of non-linear inverse problems.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geosciences, Multidisciplinary
Yajian Gao, Xiaohui Yuan, Benjamin Heit, Frederik Tilmann, Dirk-Philip van Herwaarden, Solvi Thrastarson, Andreas Fichtner, Bernd Schurr
Summary: A new seismic model for the crust and upper mantle of the south Central Andes has been derived through full waveform inversion, covering the Pampean flat subduction and adjacent Payenia steep subduction segments. The study indicates the presence of partial melts along the volcanic arc in the Payenia segment, and suggests thinning and tearing of the flat Nazca slab. Furthermore, a high-velocity anomaly in the mantle below the flat slab is interpreted as relic Nazca slab segment, signifying an earlier slab break-off triggered by the Juan Fernandez Ridge.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Geochemistry & Geophysics
Shihao Yuan, Nobuaki Fuji, Satish C. Singh
Summary: Seismic full-waveform inversion is an effective method for estimating elastic properties of the subsurface. To address the computationally expensive issue of inverting high frequencies, a localized FWI algorithm has been developed, allowing for iterative modeling locally and reducing computation effort significantly, making it widely applicable in time-lapse seismic monitoring.
Article
Geochemistry & Geophysics
Yulang Wu, George A. McMechan, Yanfei Wang
Summary: Full-waveform inversion (FWI) is a method that estimates the velocity model by fitting the observed seismic data. Traditional FWI methods can only accurately update the shallower background velocity model, while the deeper parts are less accurate. To address this issue, researchers propose a convolutional-neural-network-based reflection-waveform inversion (CNN-RWI) method. This method uses an iteratively updated convolutional neural network (CNN) to predict the true velocity model, resulting in higher accuracy.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geosciences, Multidisciplinary
Jianyong Song, Zhifang Yang, Hong Cao, Weiguang He, Wenyong Pan, Meng Li, Na Tian
Summary: Full waveform inversion is a method used to reconstruct subsurface structures by matching synthetic and observed waveforms. In this study, a combinatory inversion strategy based on seismic events is proposed to address the challenges caused by inaccurate source wavelets and model artifacts. The strategy incorporates Gaussian time windows and the optimal transport function to improve the accuracy of the inversion results. The effectiveness of the strategy is demonstrated through synthetic experiments and real-land seismic data inversion.
FRONTIERS IN EARTH SCIENCE
(2023)
Article
Geochemistry & Geophysics
Yuanyuan Li, Tariq Alkhalifah
Summary: Full waveform inversion has potential in recovering high-resolution subsurface models, with extended waveform inversion providing an effective way to mitigate cycle skipping. By treating the matching filter as an independent variable and extending the search space, a more accurate direction for velocity updates can be obtained.
GEOPHYSICAL PROSPECTING
(2021)
Article
Geochemistry & Geophysics
Guoxin Chen, Wencai Yang, Hanchuang Wang, Huamin Zhou, Xingguo Huang
Summary: This letter proposes solutions to the problem of local minima in elastic full waveform inversion (EFWI) from two aspects: low-frequency seismic data reconstruction and wave mode decomposition. The proposed methods, including envelope-based sparse-constrained deconvolution (E-SCD), dual deconvolution (D-D), and wave mode decomposition, effectively improve the resolution and accuracy of seismic data in the inversion process. Numerical experiments demonstrate the effectiveness of the proposed algorithm.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2022)
Article
Geochemistry & Geophysics
Wei Zhang, Jinghuai Gao, Zhaoqi Gao, Hongling Chen
Summary: The article presents a new approach to FWI based on adjoint-driven deep learning, using a fully convolutional network to achieve high-resolution inversion of subsurface velocity. It addresses the issues of ill-posedness, nonlinearity, and cycle-skipping that are common in traditional methods.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2021)
Article
Mathematics, Applied
Felix Lucka, Mailyn Perez-Liva, Bradley E. Treeby, Ben T. Cox
Summary: This study focuses on the challenges faced by high resolution 3D ultrasound tomography (UST) scanners and proposes a comprehensive computational strategy to overcome them, including reducing memory footprint, utilizing source encoding for stochastic gradient estimates, and implementing a stochastic LBFGS method for optimization. Extensive numerical proof-of-concept studies demonstrate the effectiveness of these methods in achieving accurate UST images within a reasonable time frame.
Review
Geochemistry & Geophysics
Yudi Pan, Lingli Gao
Summary: Shallow-seismic full-waveform inversion (FWI) is an effective method for accurate reconstruction of near-surface models. However, it suffers from ill-posedness and high computational cost. The recently proposed random-objective waveform inversion (ROWI) method shows better efficiency and robustness than FWI.
SURVEYS IN GEOPHYSICS
(2023)
Article
Geochemistry & Geophysics
Zongbo Xu, T. Dylan Mikesell
Summary: Estimating the distribution and characteristics of seismic sources from ambient seismic waves is an important problem. The commonly used methods, matched field processing and full waveform inversion, have differences in model resolution and uncertainty, which need to be further studied and compared.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Engineering, Multidisciplinary
Mingyu Yu, Fei Cheng, Jiangping Liu, Daicheng Peng, Zhijian Tian
Summary: Tunnel seismic detection methods are important for tunnel engineering, but current methods often lack accuracy in acquired geological information and physical properties. This study applies a frequency-domain acoustic full-waveform inversion method and discusses the influence of frequency group selection strategy and tunnel observation system settings on inversion results. Improved strategies are proposed to enhance resolution in imaging tunnel structure and physical parameters.
Article
Environmental Sciences
Erik Kusch, Richard Davy
Summary: Advances in climate science have made widely used observation data obsolete, prompting the development of a workflow to integrate improved data into biological analyses. The ERA5 product family offers high-resolution climate variables and can be downscaled using Kriging. KrigR provides a user-friendly tool for obtaining tailored climate data at high resolutions.
ENVIRONMENTAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Dan Bassett, Adrien Arnulf, Stuart Henrys, Dan Barker, Harm Avendonk, Nathan Bangs, Shuichi Kodaira, Hannu Seebeck, Laura Wallace, Andrew Gase, Thomas Luckie, Katie Jacobs, Brook Tozer, Ryuta Arai, David Okaya, Kimi Mochizuki, Gou Fujie, Yojiro Yamamoto
Summary: Marine multichannel and wide-angle seismic data were used to study the crustal structure along a 530 km margin-parallel transect of the Hikurangi subduction zone. The research found that the subducting Hikurangi Plateau crust is about 1 km thicker and has slightly higher mantle velocities beneath the south/central Hikurangi compared to the north Hikurangi. In the overthrusting plate, there is a significant reduction in forearc wavespeeds from south to north, accompanied by a change in seismic reflection character. The study suggests that the geological architecture of the overthrusting plate contributes to spatial variability in the location of shallow frictional transitions along the Hikurangi margin, impacting seismic and tsunami hazard.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Jiashun Yao, Michael Warner, Yanghua Wang
Summary: Surface-offset common-image gathers (CIGs) are important for seismic velocity analysis. This study proposes a method to generate CIGs by synthesizing backward wavefields based on forward wavefields, which is more accurate and cost-effective compared to backpropagation of individual traces. The proposed method utilizes nonnegative least-squares filters for sparse linear deconvolution, improving computational efficiency for higher dimensions and more complex wave equations.
Article
Plant Sciences
Erik Kusch, Richard Davy, Alistair W. R. Seddon
Summary: The study indicates that intrinsic memory is a more important component than extrinsic memory in dryland regions, and climate reanalysis data may change the detection of extrinsic vegetation memory in some global dryland regions.
JOURNAL OF ECOLOGY
(2022)
Article
Geology
Andrew C. Gase, Nathan L. Bangs, Harm J. A. Van Avendonk, Dan Bassett, Stuart A. Henrys
Summary: Using multichannel seismic images, this study reveals a correlation between the lithologic homogeneity of subduction megathrusts and their slip behavior, and finds that different regions of the megathrust exhibit different slip behaviors due to variations in rock compositions.
Article
Geosciences, Multidisciplinary
Jonathan W. Rheinlaender, Richard Davy, Einar Olason, Pierre Rampal, Clemens Spensberger, Timothy D. Williams, Anton Korosov, Thomas Spengler
Summary: The study found that the thick multiyear sea ice in the Arctic is being replaced by thinner and weaker first-year ice, making it more vulnerable to breakup by winds. Through simulations, it was discovered that a breakup event in the Beaufort Sea led to enhanced export of multiyear ice, resulting in a thinner and weaker simulated ice cover that may accelerate sea ice loss.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Thilo Wrona, Alexander C. Whittaker, Rebecca E. Bell, Robert L. Gawthorpe, Haakon Fossen, Christopher A. -L. Jackson, Marit Stokke Bauck
Summary: This study utilizes new 3D seismic reflection data from the northern North Sea to reveal a continental rift landscape dating back to the Late Permian-Early Triassic. The landscape, preserved by a combination of tectonic faults and burial sediments, provides valuable insights into the tectono-stratigraphic evolution of ancient continental rifts.
Article
Geosciences, Multidisciplinary
Nathan L. Bangs, Julia K. Morgan, Rebecca E. Bell, Shuoshuo Han, Ryuta Arai, Shuichi Kodaira, Andrew C. Gase, Xinming Wu, Richard Davy, Laura Frahm, Hannah L. Tilley, Daniel H. N. Barker, Joel H. Edwards, Harold J. Tobin, Tim J. Reston, Stuart A. Henrys, Gregory F. Moore, Dan Bassett, Richard Kellett, Valerie Stucker, Bill Fry
Summary: When large seamounts collide with the overriding plate at subduction zones, it causes permanent deformation and creates structural and compositional heterogeneities that can control megathrust slip behavior. Subducting seamounts can either temporarily lock plates, leading to large earthquakes, or redistribute stress to reduce seismic slip. Three-dimensional seismic data from the Hikurangi Plateau off the coast of New Zealand's North Island reveals that the presence of seamounts uplift the overriding plate and leave sediment lenses in their wake, with low seismic velocities and overpressured fluid-rich sediments. These sediment lenses create zones that enable slow slip, as seen in the 2014 slow-slip earthquake event. This study suggests that sediment lenses left behind by subducting seamounts can maintain long-lasting fluid pressures and support slow-slip behavior at sediment-rich subduction zones.
Article
Geosciences, Multidisciplinary
S. S. Husein, A. Fraser, G. G. Roberts, R. Bell
Summary: The use of new seismic reflection and well data has allowed us to map the stratigraphy of the Carboniferous to Neogene and analyze the potential hydrocarbon resources in the region more effectively. The improved seismic imaging has provided better understanding of salt-related structures, leading to new interpretations and implications for the geodynamic evolution of the Carnian and Carboniferous formations. The evaluation and modeling of the Lias and Carboniferous source rocks have revealed the presence of possible pre-salt hydrocarbon traps.
PETROLEUM GEOSCIENCE
(2023)
Article
Environmental Sciences
Richard Davy, Philipp Griewank
Summary: Evidence from gridded observations and climate reanalysis show that Arctic amplification peaked in the early 2000s, coinciding with the maximum loss of sea ice area, thickness, and volume. Based on CMIP6 projections and the CESM2 large ensemble, it is unlikely that Arctic amplification will be as high again in the 21st century, except under the lowest emissions scenarios where global temperatures stabilize while the Arctic continues to warm.
ENVIRONMENTAL RESEARCH LETTERS
(2023)
Article
Multidisciplinary Sciences
Ryuta Arai, Seiichi Miura, Yasuyuki Nakamura, Gou Fujie, Shuichi Kodaira, Yuka Kaiho, Kimihiro Mochizuki, Rie Nakata, Masataka Kinoshita, Yoshitaka Hashimoto, Yohei Hamada, Kyoko Okino
Summary: Geological research in the Hyuga-nada area of Japan reveals the importance of vertical fluid pathways within the overriding plate for slip behaviors and the formation of mud volcanoes.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Andrew C. Gase, Nathan L. Bangs, Demian M. Saffer, Shuoshuo Han, Peter K. Miller, Rebecca E. Bell, Ryuta Arai, Stuart A. Henrys, Shuichi Kodaira, Richard Davy, Laura Frahm, Daniel H. N. Barker
Summary: This article investigates the relationship between slow slip, fluid content, and hydrogeology in subduction zones. Through seismic imaging and ocean drilling, a widespread and previously unknown fluid reservoir was discovered at the Hikurangi margin. The research suggests that the volcaniclastic-rich upper crust at volcanic plateaus and seamounts is a major source of water that contributes to fluid budgets in subduction zones and may drive fluid overpressures along the megathrust that give rise to frequent shallow slow slip.
