Comparative study of temporal variations in the earth’s gravity field using GRACE gravity models in the regions of three recent giant earthquakes

2014 ◽  
Vol 50 (2) ◽  
pp. 177-191 ◽  
Author(s):  
V. O. Mikhailov ◽  
I. Panet ◽  
M. Hayn ◽  
E. P. Timoshkina ◽  
S. Bonvalot ◽  
...  
Keyword(s):  
Comparative Study ◽  
Gravity Field ◽  
Temporal Variations ◽  
Gravity Models ◽  
Earth’S Gravity Field

scholarly journals An improved test of the general relativistic effect of frame-dragging using the LARES and LAGEOS satellites

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Ignazio Ciufolini ◽  
Antonio Paolozzi ◽  
Erricos C. Pavlis ◽  
Giampiero Sindoni ◽  
John Ries ◽  
...  
Keyword(s):  
General Relativity ◽  
Gravity Field ◽  
Temporal Variations ◽  
Gravity Field Model ◽  
Earth’S Gravity Field ◽  
Frame Dragging ◽  
Earth Gravity ◽  
Gravity Field Determination ◽  
General Relativistic ◽  
Static Part

Abstract We report the improved test of frame-dragging, an intriguing phenomenon predicted by Einstein’s General Relativity, obtained using 7 years of Satellite Laser Ranging (SLR) data of the satellite LARES (ASI, 2012) and 26 years of SLR data of LAGEOS (NASA, 1976) and LAGEOS 2 (ASI and NASA, 1992). We used the static part and temporal variations of the Earth gravity field obtained by the space geodesy mission GRACE (NASA and DLR) and in particular the static Earth’s gravity field model GGM05S augmented by a model for the 7-day temporal variations of the lowest degree Earth spherical harmonics. We used the orbital estimator GEODYN (NASA). We measured frame-dragging to be equal to $$0.9910 \pm 0.02$$0.9910±0.02, where 1 is the theoretical prediction of General Relativity normalized to its frame-dragging value and $$\pm 0.02$$±0.02 is the estimated systematic error due to modelling errors in the orbital perturbations, mainly due to the errors in the Earth’s gravity field determination. Therefore, our measurement confirms the prediction of General Relativity for frame-dragging with a few percent uncertainty.

scholarly journals Lithospheric stress, strain and displacement changes from GRACE-FO time-variable gravity: case study for Sar-e-Pol Zahab Earthquake 2018

2020 ◽  
Vol 223 (1) ◽  
pp. 379-397
Author(s):  
Mehdi Eshagh ◽  
Farzam Fatolazadeh ◽  
Robert Tenzer
Keyword(s):  
Gravity Field ◽  
Elastic Shell ◽  
Lower Boundary ◽  
Stable Solution ◽  
Temporal Variations ◽  
Stress Strain ◽  
Satellite Gravity ◽  
Earth’S Gravity Field ◽  
Long Wavelength ◽  
Ill Posed

SUMMARY Temporal variations in the Earth's gravity field can be used for monitoring of lithospheric deformations. The network of continuously operating gravity stations is required for this purpose but a global coverage by such network is currently extremely sparse. Temporal variations in long-wavelength part of the Earth's gravity field have been, however, observed by two satellite missions, namely the Gravity Recovery And Climate Experiment (GRACE) and the GRACE Follow-On (GRACE-FO). These satellite gravity observations can be used to study long-wavelength deformations of the lithosphere. Consequently, considering the lithosphere as a spherical elastic shell and solving the partial differential equation of elasticity for it, the stress, strain and displacement inside the lithosphere can be estimated. The lower boundary of this shell is assumed to be stressed by mantle convection, which has a direct relation to the Earth's gravity field according to Runcorn's theory. Changes in gravity field lead to changes in the sublithospheric stress and the stress propagated throughout the lithosphere. In this study, we develop mathematical models in spherical coordinates for describing the stress propagation from the sublithosphere through the lithosphere. We then organize a system of observation equations for finding a special solution to the boundary-value problem of elasticity in the way that provides a stable solution. In contrast, models presented in previously published studies are ill-posed. Furthermore, we use constants of the solution determined from the boundary stresses to determine the strain and displacements leading to these stresses, while in previous studies only the stress has been considered according to rheological properties of the lithosphere. We demonstrate a practical applicability of this theoretical model to estimate the stress–strain redistribution caused by the Sar-e-Pol Zahab 2018 earthquake in Iran by using the GRACE-FO monthly solutions.

scholarly journals DIONYSOS SATELLITE OBSERVATORY AND HIGHER GEODESY LABORATORY: HISTORY AND PERSPECTIVES

2017 ◽  
Vol 50 (2) ◽  
pp. 1091
Author(s):  
A. Marinou ◽  
D. Anastasiou ◽  
X. Papanikolaou ◽  
D. Paradissis ◽  
V. Zacharis
Keyword(s):  
Gravity Field ◽  
Temporal Variations ◽  
Technological Advance ◽  
Satellite Geodesy ◽  
Research Needs ◽  
Reference Systems ◽  
Earth’S Gravity Field ◽  
Wide Range

Dionysos Satellite Observatory and Higher Geodesy Laboratory have been in operation since the 60s and their main objective is to fulfill academic and research needs, determined through the ongoing scientific and technological advance in the field of geodesy. They are involved in all scientific domains related to the determination of earth’s size and figure, as well as its temporal variations. Their field of expertise is Satellite Geodesy, (spanning a wide range of applications like reference systems, tectonic geodesy, etc.), as well as the study of the geoid and earth's gravity field.

scholarly journals ANALYSIS OF ISOSTATICALLY-BALANCED CORTICAL MODELS USING MODERN GLOBAL GEOPOTENTIAL MODELS

2017 ◽  
Vol 23 (4) ◽  
pp. 623-635
Author(s):  
Claudia Infante ◽  
Claudia Tocho ◽  
Daniel Del Cogliano
Keyword(s):  
Gravity Field ◽  
Temporal Variations ◽  
Geoid Height ◽  
Geological Structure ◽  
Earth’S Gravity Field ◽  
Isostatic Equilibrium ◽  
Geopotential Models ◽  
Show Evidence ◽  
Residual Geoid ◽  
Cortical Models

Abstract: The knowledge of the Earth's gravity field and its temporal variations is the main goal of the dedicated gravity field missions CHAMP, GRACE and GOCE. Since then, several global geopotential models (GGMs) have been released. This paper uses geoid heights derived from global geopotential models to analyze the cortical features of the Tandilia structure which is assumed to be in isostatic equilibrium. The geoid heights are suitably filtered so that the structure becomes apparent as a residual geoid height. Assuming that the geological structure is in isostatic equilibrium, the residual geoid height can be assimilated and compared to the isostatic geoid height generated from an isostatically compensated crust. The residual geoid height was obtained from the EGM2008 and the EIGEN-6C4 global geopotential models, respectively. The isostatic geoid was computed using the cortical parameters from the global crustal models GEMMA and CRUST 1.0 and from local parameters determined in the area under study. The obtained results make it clear that the isostatic geoid height might become appropriate to validate crustal models if the structures analyzed show evidence of being in isostatic equilibrium.

scholarly journals Strategy for the realisation of the International Height Reference System (IHRS)

2021 ◽  
Vol 95 (3) ◽  
Author(s):  
Laura Sánchez ◽  
Jonas Ågren ◽  
Jianliang Huang ◽  
Yan Ming Wang ◽  
Jaakko Mäkinen ◽  
...  
Keyword(s):  
Gravity Field ◽  
Reference System ◽  
International Association ◽  
Accuracy Assessment ◽  
Equipotential Surface ◽  
Precise Determination ◽  
Gravity Models ◽  
Reference Network ◽  
Global Gravity Models

AbstractIn 2015, the International Association of Geodesy defined the International Height Reference System (IHRS) as the conventional gravity field-related global height system. The IHRS is a geopotential reference system co-rotating with the Earth. Coordinates of points or objects close to or on the Earth’s surface are given by geopotential numbersC(P) referring to an equipotential surface defined by the conventional valueW0 = 62,636,853.4 m2 s−2, and geocentric Cartesian coordinatesXreferring to the International Terrestrial Reference System (ITRS). Current efforts concentrate on an accurate, consistent, and well-defined realisation of the IHRS to provide an international standard for the precise determination of physical coordinates worldwide. Accordingly, this study focuses on the strategy for the realisation of the IHRS; i.e. the establishment of the International Height Reference Frame (IHRF). Four main aspects are considered: (1) methods for the determination of IHRF physical coordinates; (2) standards and conventions needed to ensure consistency between the definition and the realisation of the reference system; (3) criteria for the IHRF reference network design and station selection; and (4) operational infrastructure to guarantee a reliable and long-term sustainability of the IHRF. A highlight of this work is the evaluation of different approaches for the determination and accuracy assessment of IHRF coordinates based on the existing resources, namely (1) global gravity models of high resolution, (2) precise regional gravity field modelling, and (3) vertical datum unification of the local height systems into the IHRF. After a detailed discussion of the advantages, current limitations, and possibilities of improvement in the coordinate determination using these options, we define a strategy for the establishment of the IHRF including data requirements, a set of minimum standards/conventions for the determination of potential coordinates, a first IHRF reference network configuration, and a proposal to create a component of the International Gravity Field Service (IGFS) dedicated to the maintenance and servicing of the IHRS/IHRF.

Theory of the earth's gravity field

1974 ◽  
Vol 10 (3) ◽  
pp. 237-238
Author(s):  
F. Morrison
Keyword(s):  
Gravity Field ◽  
Earth’S Gravity Field
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