Analytic expressions derived from a simplified model are invaluable because they often provide deep insight into geophysical phenomena. Such is the case with potential and gravity changes. Here we present of changes caused by faulting on finite rectangular plane buried in homogeneous half‐space. The can be used to evaluate coseismic surface geoid height. Observed gravimetric data combined our formulae thus constraints fault geometry magnitudes dislocation.

This paper studies the potential and gravity changes caused by dislocations in spherically symmetric earth models. We define dislocation Love numbers to describe elastic deformation of raised point sources. discuss shear tensile dislocations, which can be expressed four independent components: a vertical strike-slip, dip-slip, opening on horizontal plane, plane. The results for homogeneous model agree very well, at least within 1°, with those predicted from flat-earth theory. far-field...

With high-resolution continuous gravity recordings from a regional network of superconducting gravimeters, we have detected permanent changes in acceleration associated with recent large earthquake. Detected are smaller than 10(-8) meters seconds(-2) (1 micro-Galileo, about 10(-9) times the surface acceleration) and agree theoretical values calculated dislocation model. Superconducting gravimetry can contribute to studies secular tectonic processes.

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A R Y We derive expressions in closed form which give the gravity potential changes caused by point dislocations.They enable us to evaluate coseismic surface and geoid height.Numerical simulation shows that a great earthquake could cause height change of order 1 m.

Based on the authors' previous work, co-seismic deformations for a spherical symmetric earth model are summarized and reformulated. Unified expressions presented herein accommodate physical deformations: displacement, potential, gravity, geoid strain changes. The corresponding Green's functions derived by combining spheroidal toroidal deformations. Sign errors in publications corrected these new formulas. These developed basically deformed surface because most traditional geodetic...

We introduce a new method by which to compute global post-seismic deformation (PSD) in spherically symmetric, self-gravitating viscoelastic earth model. Previous methods are based on simplified models that neglect compressibility and/or the continuous variation of radial structure Earth. This is because previous mode summation technique cannot avoid intrinsic numerical difficulties caused innumerable poles appear realistic model considers such effects. In contrast, proposed enables both...

We have developed an integrated processing method for muon radiography and gravity anomaly data determining the 3‐D density structures of volcanoes with a higher spatial resolution than is possible by conventional inversion. In present paper, we demonstrate performance proposed performing numerical tests using synthesized data, results obtained applying to volcano, Showa‐Shinzan lava dome, Hokkaido, Japan. detailed shape vent beneath dome detected presence solidified dense near top dome. The...

Cosmic-ray muon radiography has the potential to reveal density structure of gigantic objects. It utilizes strong penetration ability high-energy muons. By measuring number muons that travel through a target object, average can be calculated along path. Since in straight paths matter, specially designed detectors generate maps with higher spatial resolution than those obtained conventional geophysical methods. However, this technique few notable limitations it only applied near-surface...

Calderas are ubiquitous topographic features of volcanos, yet caldera formation itself has not been recorded intensively by modern measurement techniques. Here we report the spatiotemporal gravity changes before and after collapse at Miyakejima volcano, Japan in 2000. A decrease as much 145 μGal (1 = 10 −8 m/s 2 ) summit area since June 1998 was detected days prior to collapse, interpreted reflecting a large void beneath volcano. Gravity initiation can mostly be corrected effect collapsed...

Today, some tens of million years after its creation by the collision between India and Asia, Tibetan Plateau is highest largest plateau on Earth. Results geological tectonic studies indicate that extending. However, almost no quantitative evidence shows whether still uplifting or thickening nowadays. Herein, we present geodetic mass loss beneath increasing crust thickness. Combined absolute gravity Global Positional System (GPS) measurements at three stations in southern southeastern Tibet...

We present a numerical formulation for computing elastic deformations caused by dislocation on finite plane in spherically symmetric earth. It is based our previous work point (Sun & Okubo 1993). The enables us to compute the displacement, potential and gravity changes due an earthquake modelled as spatially distributed dislocations. As application of finite-fault theory, we make case study theoretical observed computed results are excellent agreement with during earthquake. near field can...

We define dislocation Love numbers [ h nm ij , l k t,ij ] and Green's functions to describe the elastic deformation of Earth caused by a point study coseismic displacements in radially heterogeneous spherical model. derive harmonic expressions for shear tensile dislocations, which can be expressed four independent solutions: vertical strike slip, dip opening horizontal plane, plane. carry out calculations with model (1066A). The results indicate that dominating deformations appear near field...

The gravity disturbance caused by groundwater is derived based on hydrological physics solving nonlinear diffusion equations for three‐dimensional and temporal distributions. then estimated the spatial integral of This approach aims to resolve problems previous methods correction disturbances in data, such as instrumental drift relative gravimeters, empirical estimation assuming a linear response precipitation, use lower‐dimensional water transfer models. using proposed model consistent with...

Intriguing reciprocity relations exist between the static deformation excited by a point dislocation in SNREI earth and those generated external forces, such as tidal force, surface loading shear forces. Coseismic deformations can be rewritten follows: (1) potential change terms of tide field, (2) radial displacement load fields, (3) tangential torsional fields. The greatly reduce effort to compute coseismic crustal spherically symmetric earth.

To the present, dislocation theories for a homogeneous half‐space are often used to calculate or interpret displacements and gravity changes caused by an earthquake inverse seismic fault model. However, far‐field effects of spherical curvature radial heterogeneity have be considered. In this research, Okada [1985] Sun et al. [1996] four independent dislocations in three earth models: half‐space, sphere, heterogeneous sphere. Effects investigated through comparison displacements. Results show...

Coseismic deformations observed on the Earth surface or modeled by conventional dislocation theory cannot be compared directly with those gravity satellite missions because of spatial resolution limit and signal attenuation field. in spectrum domain should considered instead. For this purpose [e.g., Sun Okubo , 1993 ] for a spherical model can used it is expressed form harmonic. In study, analytical expressions degree variances coseismic geoid changes shear tensile sources are derived...

This paper investigates whether the Chandler period is variable in time. The first step to develop an Instantaneous Frequency Analysis trace time-varying spectrum for a non-stationary, complex-valued time series. method then applied observed polar motion find no significant fluctuation of period. Next, observational grounds hypothesis are re-examined. It shown that previous analytical technique does yield fluctuating even simulation data constant frequency. We cannot any positive evidence hypothesis.

Post-seismic deformation caused by the 2004 Sumatra-Andaman Earthquake (M = 9.3) has been observed space geodetic techniques such as Global Positioning System (GPS) and Gravity Recovery Climate Experiment (GRACE). To estimate with a spatial scale exceeding 100 km, we can use theories of global post-seismic in which Earth is treated self-gravitating viscoelastic sphere. Previous have imposed limitations on employed earth models, neglecting compressibility time variation self-gravitation or...

Abstract The gravity signal originating from magma mass movement in a volcanic conduit is retrieved the hydrologically disturbed absolute data obtained at Asama Volcano (Central Japan) 2004, using three‐dimensional hydrological model. We improve model of previous study realistic soil parameters and boundary conditions, to better estimate spatiotemporal land‐water distributions consequent disturbances. newly estimated disturbances agree with values observed by FG5 gravimeters 2004–2009 within...

The water in Earth's mantle is closely related with plate subduction and volcanism. Recent studies revealed that the wedge corner at approximately 30 km depth holds high-pressure water, where many slow earthquakes occur. To quantify how such behaves during helps us understand mechanisms of these (eventually) a part long-term cycle between interior surface Earth. However, little evidence has thus far been reported on transient flows deep water. Here, we report anomalous, negative mass...

The theory of Molodensky (1961) on dynamical effects a stratified fluid outer core upon nutations and diurnal Earth tides is reconstructed new probably much simpler ground. A equivalent to Molodensky's well represented the basis two linear equations for angular-momentum balance whole core, which differ from well-known Poincaré (1910) only in existence products inertia due deformations core. are characterized by four parameters easily computed every model usual tide equations. reciprocity...