Article
Geochemistry & Geophysics
Lixiang Ji, Zhaoyun Zong, Yaming Yang
Summary: AVAZ inversion is used to estimate subsurface medium properties from azimuthal stacked seismic data for fracture prediction. However, the low contribution of anisotropic parameters and the instability of inversion due to the condition numbers of the forward solver limit the accuracy of the results. Therefore, a new azimuthal-amplitude-difference inversion method with azimuth-velocity-anisotropic constraints is proposed to improve stability and obtain a reasonable estimation of anisotropic parameters.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
N. Hedjazian, Y. Capdeville, T. Bodin
Summary: Seismic imaging techniques are limited by the maximum frequency in observed waveforms, leading to a smoothed, effective version of the true medium. Homogenization theory helps compute effective properties of mediums with small-scale heterogeneities, and can be used in full waveform inversion. Two-stage multiscale methods break down the seismic imaging problem, revealing the benefits of using homogenization theory.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Hongliang Zhang, Jan Dettmer, Joe Wong, Kristopher A. Innanen
Summary: Estimating the locations of microseismic events is crucial for geophysical monitoring applications, but it is challenging due to the presence of finely stratified sediments and anisotropic effects. This study proposes a Bayesian approach with ORT models to simultaneously estimate anisotropy parameters, perforation shot locations, and microseismic event locations. The results highlight the importance of obtaining accurate anisotropy parameters and choosing appropriate anisotropy models for unbiased event locations. The study also emphasizes the need for sufficient microseismic data information to resolve anisotropy parameters.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Mehdi Asgharzadeh, Pouya Ahmadi, Andrej Bona, Milovan Urosevic
Summary: Orthotropic velocity models play an important role in seismic data processing and imaging by explaining velocity variations in both vertical and horizontal directions. The accuracy of estimating orthotropic parameters depends on factors such as fracture-induced symmetries, noise level, and data coverage. This study also examines the accuracy of estimating orthotropic anisotropy parameters in multilayer media and presents a method for inverting field VSP measurements.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Energy & Fuels
Changpeng Yu, Yaling Zhu, Serge Shapiro
Summary: This study proposes a geology- and rock-physics-constrained approach to estimate shale anisotropy using down-hole microseismic data sets and applies it to the Horn River shale case. The optimized anisotropic velocity model improves the accuracy of data processing and the locations of events. The research also highlights the differences in fabric anisotropy between different shale gas reservoirs.
Article
Geochemistry & Geophysics
Andrea Darrh, Yaoguo Li
Summary: This study focuses on the impact of anisotropy on geological data interpretation, specifically on extracting 1-D dipping anisotropy characteristics from magnetotelluric (MT) data. The use of different norms in inversion methods was explored to assess sensitivity to anisotropic dip angles.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Review
Chemistry, Analytical
Ariel Lellouch, Biondo L. Biondi
Summary: Distributed Acoustic Sensing (DAS) is increasingly popular in industrial and academic sectors for its high spatial and temporal resolution; a key advantage is the ability to install fibers in boreholes to record seismic signals at depth; this review article summarizes various seismic uses of downhole DAS, highlighting current limitations and potential solutions.
Article
Geochemistry & Geophysics
Da Shuai, Alexey Stovas, Yang Zhao, Xingxing Huang, Lingyi He
Summary: This study investigates the impact of fracture parameters on monoclinic anisotropy parameters, revealing that fracture density and aspect ratio have significant influence on these parameters. The study also shows differences in behavior between approximate and exact parameters in relation to azimuth angle.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Christian Poppeliers, Leiph Preston
Summary: This study presents an analysis of combining translational and rotational seismic data to invert for the time-variable source time functions corresponding to the components of the seismic moment tensor. Numerical experiments are conducted to simulate data from an underground explosion and a co-located double couple shear source, recorded on surface-mounted seismometers. The results show that the uncertainty of the estimated seismic source parameters increases when rotational seismic motions are added to the inversion with a constant number of data channels. However, when a fixed number of seismic stations are used, adding rotational seismic motions to the inversion decreases the uncertainty of the estimated seismic source parameters.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
M. van Laaten, T. Eulenfeld, U. Wegler
Summary: This study compared the results of Multiple Lapse Time Windows Analysis (MIJFWA) and full envelope inversion (Qopen) to determine intrinsic and scattering attenuation of the crust, finding similar results for both methods within their error bars.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Ahmed Zidan, Yunyue Li, Arthur Cheng
Summary: This study presents an inversion framework based on variational inference, which solves the instability issue in amplitude inversion using variational inference gradients as regularization. Through the tests with synthetic and field data examples, it achieves successful prediction of elastic properties parameters of the subsurface.
GEOPHYSICAL PROSPECTING
(2022)
Article
Geochemistry & Geophysics
Cornelis Weemstra, Janneke de Laat, Arie Verdel, Pieter Smets
Summary: This methodology presents a systematic approach to correcting instrumental timing and phase errors in seismic data acquisition and processing. By utilizing time-averaged cross-correlations of ambient seismic noise and applying a weighted least-squares inversion, the technique successfully recovers errors in field recordings, taking into account distance and signal-to-noise ratio thresholds. The method also incorporates iterative, frequency-dependent approaches to address potential frequency dependence of timing errors.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Engineering, Geological
Weiwei Zhan, Qiushi Chen
Summary: This study analyzes the nonlinear site response at liquefiable sites using long-term ground motion data from four high-quality downhole arrays. The findings indicate that the site response at liquefiable sites varies from linear to nonlinear to liquefied states as the incident motion intensity changes, and liquefaction could enhance the amplification of low-frequency and very-high-frequency ground motions.
ENGINEERING GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Xinyu Liu, Gang Tian, Jiajun Peng
Summary: The development of geophysical methods has enhanced the relevance of seismic surveys in urban areas. To address issues related to signal-to-noise ratio and resolution of seismic signals, researchers have conducted shallow surface attenuation compensation analysis based on downhole seismic data, and applied inverse Q filtering techniques to improve the resolution and accuracy of seismic sections.
JOURNAL OF APPLIED GEOPHYSICS
(2021)
Article
Geochemistry & Geophysics
B. D. E. Dando, B. P. Goertz-Allmann, D. Kuhn, N. Langet, A. M. Dichiarante, V. Oye
Summary: The text discusses the monitoring and relocation of microseismic activity at the Decatur carbon capture and storage site. By developing a modified relocation algorithm, 4293 events were successfully relocated, indicating potential improvements in recording microseismic event locations.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
T. S. Hudson, A. F. Baird, J. M. Kendall, S. K. Kufner, A. M. Brisbourne, A. M. Smith, A. Butcher, A. Chalari, A. Clarke
Summary: Icequakes, microseismic earthquakes at glaciers provide insight into ice sheet dynamics. Fiber optic cables used as Distributed Acoustic Sensors (DAS) were explored in Antarctica for monitoring icequakes, demonstrating superior performance in recording microseismic signals compared to conventional geophones. The study also successfully applied DAS for full-waveform source mechanism inversions and developed an effective 2D DAS array geometry for accurate characterization of shear-wave splitting due to anisotropic ice fabric, with relevance for other microseismic environments.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Sacha Lapins, Berhe Goitom, J-Michael Kendall, Maximilian J. Werner, Katharine V. Cashman, James O. S. Hammond
Summary: In this study, a deep learning model for automating phase arrival detection at Nabro volcano is developed using transfer learning with limited training data. The new model shows improved classification accuracy and arrival time residuals compared to existing models, and is more efficient in processing seismic data from multiple stations.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
K. Leptokaropoulos, N. Harmon, S. P. Hicks, C. A. Rychert, D. Schlaphorst, J. M. Kendall
Summary: Research suggests that tidal forces can trigger seismic activity, particularly during low tides. Data from ocean bottom seismometers show that low ocean levels and decreasing water levels can lead to higher magnitude seismic activity rates. Seismic bursts may also be associated with extensional stresses induced by high tides.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Thomas S. Hudson, J-Michael Kendall, Matthew E. Pritchard, Jonathan D. Blundy, Joachim H. Gottsmann
Summary: Uturuncu volcano in the Bolivian Andes is seismically active and lies above the world's largest silicic partial melt. Analysis of seismic activity reveals fault orientations and potential fluid migration mechanisms. The study suggests using moment magnitudes for accurate b-value analysis and interprets b-values > 1 in terms of fluid-enhanced seismicity.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Environmental Sciences
Sam Fankhauser, Stephen M. Smith, Myles Allen, Kaya Axelsson, Thomas Hale, Cameron Hepburn, J. Michael Kendall, Radhika Khosla, Javier Lezaun, Eli Mitchell-Larson, Michael Obersteiner, Lavanya Rajamani, Rosalind Rickaby, Nathalie Seddon, Thom Wetzer
Summary: The concept of net-zero carbon emissions is rooted in physical climate science but is operationalized through social, political, and economic systems. Seven critical attributes have been identified for the successful implementation of net zero, emphasizing the urgency of emission reductions, coverage of all emission sources, cautious use of carbon dioxide removals, and alignment with broader sustainable development objectives.
NATURE CLIMATE CHANGE
(2022)
Article
Geosciences, Multidisciplinary
Tom Kettlety, J. Michael Kendall, Diana C. Roman
Summary: Estimating the volume of intruded magma is crucial for predicting volcanic activity. Geodetic modeling is a useful tool for providing these estimates, but it has limitations in submarine and highly vegetated areas. This study explores the use of seismic moment release estimates as a complementary approach. By comparing the moment-volume scaling of several volcanic earthquake sequences and injection-induced seismicity, the researchers find a notable similarity in scaling within the volcanic sequences. This suggests a distinctive geological condition for volcanoes compared to induced seismicity settings, and the possibility of estimating intruded volume without geodetic information.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Wen Zhou, Antony Butcher, Alex M. Brisbourne, Sofia-Katerina Kufner, J-Michael Kendall, Anna L. Stork
Summary: Distributed Acoustic Sensing (DAS) and seismic noise interferometry (SI) can be used for glacier measurements and near-surface studies. We propose two approaches to improve DAS and seismic noise cross-correlation results.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2022)
Article
Multidisciplinary Sciences
Stephen P. Hicks, Lidong Bie, Catherine A. Rychert, Nicholas Harmon, Saskia Goes, Andreas Rietbrock, Songqiao Shawn Wei, Jenny S. Collier, Timothy J. Henstock, Lloyd Lynch, Julie Prytulak, Colin G. Macpherson, David Schlaphorst, Jamie J. Wilkinson, Jonathan D. Blundy, George F. Cooper, Richard G. Davy, John -Michael Kendall
Summary: Volatiles expelled from subducted plates affect the melting of the overlying mantle, which is important for arc volcanism. This study examines seismic attenuation beneath the Lesser Antilles arc and reveals the role of expelled fluids and melt in controlling volcanism. The results show that cold boundary layers transport fluids towards the back-arc, while warm mantle beneath the back-arc feeds arc volcanoes.
Article
Geochemistry & Geophysics
David Schlaphorst, Catherine A. Rychert, Nicholas Harmon, Stephen P. Hicks, Petros Bogiatzis, J-Michael Kendall, Rachel E. Abercrombie
Summary: Seismicity along transform faults provides important constraints for understanding earthquake ruptures. This study presents the first local seismicity catalog of slow spreading ridges based on data recorded by a temporary broad-band network. Most of the earthquakes are located along the Chain Transform Fault, Romanche transform fault, and the Mid-Atlantic Ridge. The seismic events are characterized by normal faulting along the ridge and strike-slip faulting along the transforms, with some reverse mechanisms.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geosciences, Multidisciplinary
T. S. Hudson, J. M. Kendall, J. D. Blundy, M. E. Pritchard, P. MacQueen, S. S. Wei, J. H. Gottsmann, S. Lapins
Summary: Mapping fluid distribution in the crust below Uturuncu volcano using seismic attenuation tomography reveals partially and fully fluid-saturated areas along aligned faults and fractures. Pressure-temperature profiles and conductivity data help identify the likely fluid composition, with shallow regions of dry and H2O/brine-saturated crust, and a deeper supercritical H2O/brine column. These observations provide insights into Uturuncu's transcrustal hydrothermal system and demonstrate the potential application of such methods for mapping crustal fluid pathways and hydrothermal/geothermal systems.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
T. S. Hudson, S. K. Kufner, A. M. Brisbourne, J. M. Kendall, A. M. Smith, R. B. Alley, R. J. Arthern, T. Murray
Summary: This study investigates the slip of glaciers over the underlying bed, which is the dominant mechanism governing the migration of ice into the oceans and contributes to sea-level rise. The researchers use passive seismic observations to measure frictional shear stress and slip at the bed of the Rutford Ice Stream in Antarctica. They find that basal shear stresses and slip rates vary significantly in both space and time, indicating that the bed is more complex than previously assumed in ice stream models. This research provides important constraints for ice-dynamics models and is critical for understanding the contribution of ice mass loss to sea-level rise.
Article
Geosciences, Multidisciplinary
S. -K. Kufner, J. Wookey, A. M. Brisbourne, C. Martin, T. S. Hudson, J. M. Kendall, A. M. Smith
Summary: The crystal orientation fabric of glacier ice is crucial in determining its strength and flow behavior, making it an important factor in ice flow modeling. In this study, the authors demonstrate that shear-wave splitting (SWS) measured through glacial microseismicity can be used to infer seismic anisotropy and ice fabric in a statistical sense. By analyzing over 200,000 SWS measurements from a seismic network near Rutford Ice Stream in Antarctica, the researchers were able to identify a three-layer ice fabric structure with varying strengths and deformability along the flow direction. Their findings suggest that fast-flowing ice streams may require a more complex integration of viscosity in ice sheet models.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2023)
Article
Geochemistry & Geophysics
M. Gauntlett, T. Hudson, J. -M. Kendall, N. Rawlinson, J. Blundy, S. Lapins, B. Goitom, J. Hammond, C. Oppenheimer, G. Ogubazghi
Summary: Understanding the crustal structure and the movement of fluids beneath a volcano is crucial for assessing volcanic hazard and exploring geothermal potential. This study uses earthquake tomography to image the seismic velocity structure beneath Nabro volcano in Ethiopia. The findings suggest the presence of solidified rocks and a primary melt storage region that fed the 2011 eruption. The observations also indicate the persistence of magma and the potential for geothermal exploration.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
K. Leptokaropoulos, C. A. Rychert, N. Harmon, J. M. Kendall
Summary: Based on the study of the Chain transform in the equatorial Mid-Atlantic, it is found that the seismic activity is highest in the eastern area, while the western and central areas have lower seismic rates but release the majority of seismic moment. This segmentation is possibly due to variable fluid circulation and alteration.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geology
J. M. Kendall, D. Schlaphorst, C. A. Rychert, N. Harmon, M. Agius, S. Tharimena
Summary: Parallel melt accumulation along the Mid-Atlantic Ridge was found, and this may enhance the driving forces of the plates.