The Experts below are selected from a list of 87723 Experts worldwide ranked by ideXlab platform
Robert Vanâ Derâ D Hilst - One of the best experts on this subject based on the ideXlab platform.
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a new algorithm for three dimensional joint inversion of Body Wave and surface Wave data and its application to the southern california plate boundary region
Journal of Geophysical Research, 2016Co-Authors: Hongjian Fang, Haijiang Zhang, A A Allam, Dimitri Zigone, Yehuda Benzion, C H Thurber, Robert Vanâ Derâ D HilstAbstract:We introduce a new algorithm for joint inversion of Body Wave and surface Wave data to get better 3-D P Wave (Vp) and S Wave (Vs) velocity models by taking advantage of the complementary strengths of each data set. Our joint inversion algorithm uses a one-step inversion of surface Wave traveltime measurements at different periods for 3-D Vs and Vp models without constructing the intermediate phase or group velocity maps. This allows a more straightforward modeling of surface Wave traveltime data with the Body Wave arrival times. We take into consideration the sensitivity of surface Wave data with respect to Vp in addition to its large sensitivity to Vs, which means both models are constrained by two different data types. The method is applied to determine 3-D crustal Vp and Vs models using Body Wave and Rayleigh Wave data in the Southern California plate boundary region, which has previously been studied with both double-difference tomography method using Body Wave arrival times and ambient noise tomography method with Rayleigh and Love Wave group velocity dispersion measurements. Our approach creates self-consistent and unique models with no prominent gaps, with Rayleigh Wave data resolving shallow and large-scale features and Body Wave data constraining relatively deeper structures where their ray coverage is good. The velocity model from the joint inversion is consistent with local geological structures and produces better fits to observed seismic Waveforms than the current Southern California Earthquake Center (SCEC) model.
A A Allam - One of the best experts on this subject based on the ideXlab platform.
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a new algorithm for three dimensional joint inversion of Body Wave and surface Wave data and its application to the southern california plate boundary region
Journal of Geophysical Research, 2016Co-Authors: Hongjian Fang, Haijiang Zhang, A A Allam, Dimitri Zigone, Yehuda Benzion, C H Thurber, Robert Vanâ Derâ D HilstAbstract:We introduce a new algorithm for joint inversion of Body Wave and surface Wave data to get better 3-D P Wave (Vp) and S Wave (Vs) velocity models by taking advantage of the complementary strengths of each data set. Our joint inversion algorithm uses a one-step inversion of surface Wave traveltime measurements at different periods for 3-D Vs and Vp models without constructing the intermediate phase or group velocity maps. This allows a more straightforward modeling of surface Wave traveltime data with the Body Wave arrival times. We take into consideration the sensitivity of surface Wave data with respect to Vp in addition to its large sensitivity to Vs, which means both models are constrained by two different data types. The method is applied to determine 3-D crustal Vp and Vs models using Body Wave and Rayleigh Wave data in the Southern California plate boundary region, which has previously been studied with both double-difference tomography method using Body Wave arrival times and ambient noise tomography method with Rayleigh and Love Wave group velocity dispersion measurements. Our approach creates self-consistent and unique models with no prominent gaps, with Rayleigh Wave data resolving shallow and large-scale features and Body Wave data constraining relatively deeper structures where their ray coverage is good. The velocity model from the joint inversion is consistent with local geological structures and produces better fits to observed seismic Waveforms than the current Southern California Earthquake Center (SCEC) model.
Dimitri Zigone - One of the best experts on this subject based on the ideXlab platform.
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a new algorithm for three dimensional joint inversion of Body Wave and surface Wave data and its application to the southern california plate boundary region
Journal of Geophysical Research, 2016Co-Authors: Hongjian Fang, Haijiang Zhang, A A Allam, Dimitri Zigone, Yehuda Benzion, C H Thurber, Robert Vanâ Derâ D HilstAbstract:We introduce a new algorithm for joint inversion of Body Wave and surface Wave data to get better 3-D P Wave (Vp) and S Wave (Vs) velocity models by taking advantage of the complementary strengths of each data set. Our joint inversion algorithm uses a one-step inversion of surface Wave traveltime measurements at different periods for 3-D Vs and Vp models without constructing the intermediate phase or group velocity maps. This allows a more straightforward modeling of surface Wave traveltime data with the Body Wave arrival times. We take into consideration the sensitivity of surface Wave data with respect to Vp in addition to its large sensitivity to Vs, which means both models are constrained by two different data types. The method is applied to determine 3-D crustal Vp and Vs models using Body Wave and Rayleigh Wave data in the Southern California plate boundary region, which has previously been studied with both double-difference tomography method using Body Wave arrival times and ambient noise tomography method with Rayleigh and Love Wave group velocity dispersion measurements. Our approach creates self-consistent and unique models with no prominent gaps, with Rayleigh Wave data resolving shallow and large-scale features and Body Wave data constraining relatively deeper structures where their ray coverage is good. The velocity model from the joint inversion is consistent with local geological structures and produces better fits to observed seismic Waveforms than the current Southern California Earthquake Center (SCEC) model.
Alexander G. Ramm - One of the best experts on this subject based on the ideXlab platform.
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Many-Body Wave scattering problems in the case of small scatterers
arXiv: Mathematical Physics, 2012Co-Authors: Alexander G. RammAbstract:Formulas are derived for solutions of many-Body Wave scattering problems by small particles in the case of acoustically soft, hard, and impedance particles embedded in an inhomogeneous medium. The case of transmission (interface) boundary conditions is also studied in detail. The limiting case is considered, when the size $a$ of small particles tends to zero while their number tends to infinity at a suitable rate. Equations for the limiting effective (self-consistent) field in the medium are derived. The theory is based on a study of integral equations and asymptotics of their solutions as $a\to 0$. The case of Wave scattering by many small particles embedded in an inhomogeneous medium is also studied.
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numerical solution of many Body Wave scattering problem for small particles
arXiv: Computational Physics, 2012Co-Authors: M I Andriychuk, Alexander G. RammAbstract:A numerical approach to the problem of Wave scattering by many small particles is developed under the assumptions k >a, where a is the size of the particles and d is the distance between the neighboring particles. On the Wavelength one may have many small particles. An impedance boundary conditions are assumed on the boundaries of small particles. The results of numerical simulation show good agreement with the theory. They open a way to numerical simulation of the method for creating materials with a desired refraction coefficient.
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many Body Wave scattering by small bodies and applications ii
arXiv: Mathematical Physics, 2009Co-Authors: Alexander G. Ramm, A RonaAbstract:The many-Body Wave scattering problem is studied in the case where the bodies are small, $ka \ll 1$, where $a$ is the characteristic size of a Body. The limiting case when $a \to 0$ and the total number of the small bodies is $M = O (a^{2-\kappa})$ is studied, $\kappa\in (0,1)$ is a parameter, the distance $d$ between neighboring bodies is $d=O(a^{(2-\kappa)/3}$.
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many Body Wave scattering by small bodies and applications
Journal of Mathematical Physics, 2007Co-Authors: Alexander G. RammAbstract:A rigorous reduction of the many-Body Wave scattering problem to solving a linear algebraic system is given bypassing solving the usual system of integral equation. The limiting case of infinitely many small particles embedded into a medium is considered and the limiting equation for the field in the medium is derived. The impedance boundary conditions are imposed on the boundaries of small bodies. The case of Neumann boundary conditions (acoustically hard particles) is also considered. Applications to creating materials with a desired refraction coefficient are given. It is proved that by embedding a suitable number of small particles per unit volume of the original material with suitable boundary impedances, one can create a new material with any desired refraction coefficient. The governing equation is a scalar Helmholtz equation, which one obtains by Fourier transforming the Wave equation.
David J. Schodt - One of the best experts on this subject based on the ideXlab platform.
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Seismic Characterization of the Nevada National Security Site Using Joint Body Wave, Surface Wave, and Gravity InversionSeismic Characterization of the NNSS Using Joint Body Wave, Surface Wave, and Gravity Inversion
Bulletin of the Seismological Society of America, 2019Co-Authors: Leiph Preston, Christian Poppeliers, David J. SchodtAbstract:ABSTRACT As a part of the series of Source Physics Experiments (SPE) conducted on the Nevada National Security Site in southern Nevada, we have developed a local-to-regional scale seismic velocity model of the site and surrounding area. Accurate earth models are critical for modeling sources like the SPE to investigate the role of earth structure on the propagation and scattering of seismic Waves. We combine seismic Body Waves, surface Waves, and gravity data in a joint inversion procedure to solve for the optimal 3D seismic compressional and shear-Wave velocity structures and earthquake locations subject to model smoothness constraints. Earthquakes, which are relocated as part of the inversion, provide P- and S-Body-Wave absolute and differential travel times. Active source experiments in the region augment this dataset with P-Body-Wave absolute times and surface-Wave dispersion data. Dense ground-based gravity observations and surface-Wave dispersion derived from ambient noise in the region fill in many areas where Body-Wave data are sparse. In general, the top 1–2 km of the surface is relatively poorly sampled by the Body Waves alone. However, the addition of gravity and surface Waves to the Body-Wave dataset greatly enhances structural resolvability in the near surface. We discuss the methodology we developed for simultaneous inversion of these disparate data types and briefly describe results of the inversion in the context of previous work in the region.