Article
Environmental Sciences
Yusaku Tanaka
Summary: This study analyzed the time series of gravity data observed by the GRACE and GRACE Follow-On satellites and detected the spatial distribution of coseismic gravity changes mainly due to crustal deformation by the 2018 Fiji earthquake. The results were inconsistent with the numerical calculation using seismic wave data, highlighting the need for future research combining satellite gravimetry and seismic wave data to explain crustal deformation.
Article
Geosciences, Multidisciplinary
Kosuke Heki, Mala S. Bagiya, Yuki Takasaka
Summary: The rise times of earthquake moment release affect the spectra of seismic waves. Slow fault movements in tsunami earthquakes can generate larger tsunamis than expected, while regular earthquakes have normal effects. Measurements of atmospheric waves excited by coseismic vertical crustal movements show that the amplitudes of internal gravity waves increase with magnitude, while the amplitudes of acoustic waves in tsunami earthquakes are normal.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Mu Xuan, Bai YongLiang, Shan XinJian, Zhang GuoHong, Wang ZhenJie
Summary: This study aims to quantify the sensitivity of coseismic gravity changes to different source slip parameters in order to improve the accuracy of source slip parameter inversion. Through forward modeling and dimensionless sensitivity analysis method, the sensitivity of coseismic gravity changes to depth, dip, slip, and rake in the 2004 Sumatra earthquake was evaluated. The results showed that slip and rake had higher sensitivity to coseismic gravity changes, and it is important to pay attention to determining them in the inversion process.
CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
(2022)
Article
Astronomy & Astrophysics
Bo Zhong, Xianpao Li, Jianli Chen, Qiong Li
Summary: To suppress correlated noise, a series of constrained monthly gravity field solutions named WHU-GRACE-GPD01s were developed from August 2002 to July 2016 using GRACE-based geopotential differences. The constrained solutions were estimated using Kaula regularization and their performance was validated against official SH solutions and mass concentration solutions. The results showed that the constrained solutions were comparable to the official SH solutions and can be used without postprocessing.
EARTH AND SPACE SCIENCE
(2023)
Article
Geosciences, Multidisciplinary
Orlando Alvarez, Stefanie Pechuan Canet, Mario Gimenez, Andres Folguera
Summary: Over the past two decades, space geodesy has greatly improved the study of large megathrust earthquakes by accurately mapping rupture areas, slip distribution, and seismic coupling. By modeling gravity gradients and comparing them with coseismic slip models, we have identified mass heterogeneities and their relationship with seismic activity. This research suggests that combining geodetic and seismological data can help identify and monitor areas with higher seismic hazard potential worldwide.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Geochemistry & Geophysics
Marie Bouih, Isabelle Panet, Dominique Remy, Laurent Longuevergne, Sylvain Bonvalot
Summary: Subduction zones megathrust faults are a major cause of the world's largest earthquakes. However, the role of deeper subduction processes in earthquake generation is poorly understood. In this study, the variations of the Earth's gravity gradients derived from GRACE geoid models are analyzed from 2003 to 2014. The analysis reveals a large-amplitude gravity gradient signal north of the epicentral area in the three months prior to the earthquake. The results suggest that these signals are related to mass redistributions within the solid Earth on the continental side of the subduction zone. The study highlights the importance of monitoring the Earth's time-varying gravity field to better understand the seismic cycle and dynamic processes in subduction zones.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Geochemistry & Geophysics
Y. Cui, C. Zheng, L. Jiang, J. Huang, F. Sun, Z. Zou, J. Du
Summary: This study investigated the three-dimensional (3D) temporal variations and correlation analysis of CO, CH4 and O3 concentrations associated with two great earthquakes offshore Sumatra, Indonesia. The results showed that large amounts of gases were emitted from the Earth's crust before, during and after the earthquakes compared to the earthquake-free periods and background areas. Anomalies in gas concentrations occurred along the fault system and the correlation coefficients between the gas parameters increased closer to the earthquake occurrence. The findings are helpful in understanding geochemical earthquake anomalies and the mechanism of lithosphere-atmosphere-ionosphere coupling.
Article
Environmental Sciences
Ming Xu, Xiaoyun Wan, Runjing Chen, Yunlong Wu, Wenbing Wang
Summary: This study compares the errors of GRACE/GFO with coseismic gravity variations caused by large earthquakes, showing that the precision of GFO monthly models is higher but still faces challenges in accurately extracting coseismic signals.
Article
Geochemistry & Geophysics
Bramha Dutt Vishwakarma, Yann Ziegler, Jonathan L. Bamber, Sam Royston
Summary: The visco-elastic response of the solid Earth to glacial cycles and surface mass change can be detected using geodetic observation systems. In order to better understand current surface mass change driven by climate change, it is necessary to consider the glacial isostatic adjustment (GIA) signal. A new framework is proposed that uses geophysical relations to estimate data-driven GIA solutions, which differ significantly from traditional forward models in certain regions.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Environmental Sciences
Mokhamad Nur Cahyadi, Deasy Arisa, Ihsan Naufal Muafiry, Buldan Muslim, Ririn Wuri Rahayu, Meilfan Eka Putra, Mega Wulansari, Bambang Setiadi, Andria Arisal, Pakhrur Razi, Syachrul Arief
Summary: Ionospheric disturbances caused by the 2016 West Sumatra earthquake have been studied using total electron content measurements. A three-dimensional tomography method was used to analyze the anomalous movement of the ionosphere after the earthquake. The results showed that a positive anomaly appeared 11 minutes after the earthquake and moved 1 degree towards the geomagnetic field every minute.
Article
Geochemistry & Geophysics
Sk. Shamim, Prosanta Kumar Khan, Sarada P. Mohanty, Manoranjan Mohanty
Summary: The Andaman-Nicobar-Sumatra subduction margin has a complex geological structure with the presence of multiple regional faults between the volcanic arc, fore-arc basin, and trench, causing deformation of lithospheric plates. The observed negative gravity anomaly in the margin's gravity model may be associated with a fore-arc shear fault above fractured oceanic crust with a thick sedimentary layer, located in an area of sharp bending of the converging Indian lithosphere in the fore-arc basin.
SURVEYS IN GEOPHYSICS
(2021)
Article
Geochemistry & Geophysics
Apsara Sharma Dhakal, Irene Molinari, Lapo Boschi
Summary: Different methods of mapping seismic rupture in space and time often give inconsistent results for the same event. Building on previous work, we use a combination of time-reversal and backpropagation of seismic surface wave recordings to study the focusing of the time-reversed field at the seismic source. Our new method combines seismic time reversal with a surface wave ray-tracing algorithm based on a generalized spherical-harmonic parametrization of surface wave phase velocity, accounting for azimuthal anisotropy.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geosciences, Multidisciplinary
Xuezhong Chen, Yane Li, Lijuan Chen
Summary: This study investigated the temporal variations of the b value in the aftershock zone prior to the 2004 Sumatra earthquake. The results showed that the b value significantly decreased from 1990 to 1999 and remained low from 2000 onwards. The study also found a larger relative decline in the b value near the epicenter of the Sumatra event. These findings can help to better constrain the location of future great earthquakes in seismic hazard analysis.
GEOMATICS NATURAL HAZARDS & RISK
(2022)
Article
Geosciences, Multidisciplinary
Orlando Alvarez, Mario Gimenez, Andres Folguera
Summary: In the past decade, the three largest and most destructive earthquakes with associated tsunamis occurred. Technological and scientific advancements have allowed for the unprecedented study and modeling of these phenomena. Gravity field models have been used to infer mass displacements associated with these events, yielding good results when compared with other methods. The study of the 2011 Tohoku-Oki earthquake revealed that the maximum slip occurred near a lobe of minimum Tzz and that the rupture was influenced by density structures.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Geochemistry & Geophysics
Yushiro Fujii, Kenji Satake, Shingo Watada, Tung-Cheng Ho
Summary: The study reexamined the slip distribution on faults of the 2004 Sumatra-Andaman earthquake through inversion of tsunami data with phase-corrected Green's functions and satellite altimetry data, resulting in the identification of the best slip distribution model. This model performs well in reproducing tsunami waveforms, significantly improving the reproducibility of spatiotemporal SSHs.
PURE AND APPLIED GEOPHYSICS
(2021)
Article
Geochemistry & Geophysics
Alexander L. Burky, Jessica C. E. Irving, Frederik J. Simons
Summary: The study explores the mantle structure of the Bermuda rise, attempting to understand the connection between the mantle plume and surface manifestations in Bermuda through seismic records and wave-speed models. By analyzing the structure of the mantle transition zone, it is found that the transition zone may be thicker than average, which is inconsistent with the traditional mantle plume model.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(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)
Review
Geosciences, Multidisciplinary
Michal Sprlak, Shin-Chan Han
Summary: This article discusses the use of spherical harmonic expansion for gravitational field modeling, highlighting limitations of external spherical harmonic parametrization and drawing clear conclusions. The study reveals issues in global lunar gravitational field models and provides important insights for future gravitational field determinations of other planetary bodies.
EARTH-SCIENCE REVIEWS
(2021)
Article
Geochemistry & Geophysics
Sirawich Pipatprathanporn, Frederik J. Simons
Summary: A fleet of autonomously drifting profiling floats known as mermaid monitors seismic activity using hydrophones inside oceans. The floats recorded signals from 213 global earthquakes, with only 10 automatically reported. After removing seismic and other signals, infrasonic ambient noise recorded at 1500 m depth was analyzed, showing interactions of oceanic surface gravity waves.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Mohsen Feizi, Mehdi Raoofian-Naeeni, Shin-Chan Han
Summary: This study focuses on local geopotential field modelling over a mountainous region in Tanzania using vector airborne gravity data. The results indicate that the local models are significantly more accurate than global models and fully exploit the airborne vector data with minimal measurement error. Additionally, regional models constrained by vertical or horizontal gravity observations are found to be less accurate than 3-D gravity data inversion models.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2021)
Article
Geochemistry & Geophysics
Joel D. Simon, Frederik J. Simons, Jessica C. E. Irving
Summary: This study presents the first 16 months of data from a mobile array of diving instruments in the South Pacific, focusing on recording seismic wavefields and analyzing traveltime anomalies for seismic tomography. The data collected will be used for future earthquake research and contribute to understanding the Earth's mantle.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Joel D. Simon, Frederik J. Simons, Jessica C. E. Irving
Summary: MERMAID is a passively drifting oceanic diving float that can quickly transmit seismic records after global earthquakes.It is able to map 3D mantle wavespeed anomalies with high resolution under the Pacific in French Polynesia, and the returned data contain not only P-wave information but also acoustic signals generated by earthquakes heard across the globe.
SEISMOLOGICAL RESEARCH LETTERS
(2021)
Article
Multidisciplinary Sciences
Shin-Chan Han, Khosro Ghobadi-Far, In-Young Yeo, Christopher M. McCullough, Eunjee Lee, Jeanne Sauber
Summary: The size and timing of monsoon floods in Bangladesh are challenging to measure accurately. Utilizing satellite observations and flood models can provide important information for understanding and forecasting floods in the region.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Geochemistry & Geophysics
Khosro Ghobadi-Far, Shin-Chan Han, Christopher M. McCullough, David N. Wiese, Richard D. Ray, Jeanne Sauber, Linus Shihora, Henryk Dobslaw
Summary: This article examines the sensitivity of GRACE-FO LRI measurements to sub-monthly time-variable gravity signals and presents an alternative analysis method for studying short-term mass changes. By combining the LRI observations with other data and models, high-frequency oceanic mass variability and sub-monthly variations in surface water can be detected.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Qiancheng Liu, Umair bin Waheed, Dmitry Borisov, Frederik J. Simons, Fuchun Gao, Paul Williamson
Summary: Passive seismic inversion at the reservoir scale using a large and dense array of seismic sensors in the Himalayan foothills has been successfully employed to characterize earthquake sources and build wave speed models. The workflow includes waveform fitting procedures, data selection based on signal-to-noise considerations, and spectral-element simulations of wave propagation. The study presents updated centroid moment tensor solutions for 86 seismic events and provides a detailed analysis of the resulting catalog.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Statistics & Probability
Arthur P. Guillaumin, Adam M. Sykulski, Sofia C. Olhede, Frederik J. Simons
Summary: We propose a computationally and statistically efficient method to estimate the parameters of a stochastic covariance model observed on a regular spatial grid. Our method, called the Debiased Spatial Whittle likelihood, corrects the bias caused by boundary effects and aliasing and allows for missing data and irregular sampling boundaries. We provide a theoretical framework that ensures consistency and asymptotic normality in various practical settings, including missing data and non-Gaussian processes. The implementation guidelines ensure that the estimation procedure can be conducted in O(nlogn) operations, maintaining computational scalability for large datasets.
JOURNAL OF THE ROYAL STATISTICAL SOCIETY SERIES B-STATISTICAL METHODOLOGY
(2022)
Article
Environmental Sciences
Mehdi Khaki, Shin-Chan Han, Khosro Ghobadi-Far, In-Young Yeo, Natthachet Tangdamrongsub
Summary: This article introduces a new method that directly assimilates data from the GRACE-FO laser ranging interferometer into a land surface model, overcoming the limitations of traditional approaches. The proposed method provides more accurate information on short time scales and has been applied globally and evaluated for its performance.
WATER RESOURCES RESEARCH
(2023)
Article
Astronomy & Astrophysics
Shin-Chan Han, Simon McClusky, T. Dylan Mikesell, Lucie Rolland, Emile Okal, Craig Benson
Summary: Multiple passages of atmospheric waves were observed after the HTHH volcanic eruption, perturbing the ionosphere and producing TIDs. New observations of TIDs at high altitudes (>550 km) were made using CubeSat GPS tracking data, which provided complementary information to ground receivers due to their larger spatial coverage over a shorter period of time. The TIDs traveled globally and reached high altitudes, indicating a speed of approximately 350 m/s.
EARTH AND SPACE SCIENCE
(2023)
Editorial Material
Geochemistry & Geophysics
Isabelle Manighetti, Rachel Abercrombie, Yves Bernabe, Michael Bostock, Mark J. Dekkers, Satoshi Ide, Douglas R. Schmitt, Shin-Chan Han, Paul Tregoning
Summary: The editors of JGR-Solid Earth express their gratitude to the peer reviewers who contributed in reviewing articles for the journal in 2022.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Engineering, Electrical & Electronic
Mehdi Khaki, Shin-Chan Han, In-Young Yeo, Andrew Frost
Summary: The study validates the reliability of CYGNSS in Australia for monitoring soil moisture changes and identifying inundated areas, using a constellation of microsatellites to observe global positioning system signals. By comparing with various measurements and applying decomposition methods, the study analyzes the relationship between CYGNSS and independent measurements, as well as its response to extreme climate events.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2021)
