Download or read book The Effects of Seismic Anisotropy on Regional Seismic Wave Propagation written by and published by . This book was released on 1997 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crustal rocks can be highly anisotropic, due to (1) oriented minerals, (2) oriented cracks, and/or (3) thin layers of material with different elastic stiffnesses. Crustal Love and Rayleigh surface waves couple strongly for anisotropic structures that do not possess a vertical axis of symmetry, and cause explosions to generate significant shear motion on the transverse component of seismograms. We developed theory and 1-D layered-media synthetic seismogram codes for anisotropy with an arbitrary axis of symmetry. One code version can synthesize surface waves with periods 100 > T > 0.4 sec. Another code version can synthesize teleseismic body wave reverberations up to 5 Hz. We determined that a tilted axis of symmetry enhances Love-Rayleigh coupling and the scattering of P-waves (compressional) to S-waves (shear). Using P-S scattering, we found evidence for strong (> 10%) anisotropy in the deepest and shallowest crustal layers beneath seismic station ARU (Arti, Russia), an 'open' seismic observatory proximal to the Novaya Zemlya nuclear test site. We also developed a wavelet-based signal processing algorithm that picks out correlated 'signals' from uncorrelated 'noise' in an optimally bandpassed manner. Using the Terrascope regional array in California we applied this algorithm to reconstruct, for a single correlated signal anomalous amplitudes and polarizations at individual stations, allowing more 'signal' to be recovered than via standard 'stacking.'

Download or read book The Effects of Anisotropy on Regional Seismic Wave Propagation written by Jeffrey Park and published by . This book was released on 1995 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have examined the effect of seismic anisotropy on the scattering of surface waves in actively-deforming continental regions, many of which occur in areas of nonproliferation concern. We have approached the problem from three angles, (1) we have developed waveform inversion methods for Love-Rayleigh coupling in seismic data from the Tibetan Plateau and Tien Shan region, (2) we have developed a flat-layered surface wave code to study the effect of crust and upper-mantle anisotropy on crustal resonances, and (3) we have advanced wavelet-based signal processing methods to estimate the polarization of coherent seismic energy across a broadband seismic array. In data from the recent portable broadband PASSCAL deployment in Tibet, we found clear evidence of long-period Love-to-Rayleigh scattering that is best explained by lateral gradients of anisotropy in the upper mantle, developed in the course of the compression and uplift of the plateau. We developed a modal summation technique for waveform perturbations that allowed us to infer that both S and P wave anisotropy, with a ratio consistent with the mineral alignment of sheared peridotite, in the depth range 100-300 km are necessary to fit the observed data. Using a plane-layered geometry, we are investigating the effect of crust and upper mantle anisotropy on Love-Rayleigh coupling in the 5-30 second period range. Most previous studies have posited a horizontal or vertical axis of symmetry for seismic anisotropy, but our code can incorporate a tilted axis of symmetry, which enhances coupling and scattering effects. Such dipping geometries could develop in the crust as a result of thrust ramps in compressive tectonic regimes, either in the form of oriented crystals in shear zones or fine-layering of isotropic material.

Download or read book Seismic Anisotropy in the Earth written by V. Babuska and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Understanding Seismic Anisotropy in Exploration and Exploitation Second Edition written by Leon Thomsen and published by SEG Books. This book was released on 2014-10-01 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding Seismic Anisotropy in Exploration and Exploitation (second edition) by Leon Thomsen is designed to show you how to recognize the effects of anisotropy in your data and to provide you with the intuitive concepts that you will need to analyze it. Since its original publication in 2002, seismic anisotropy has become a mainstream topic in exploration geophysics. With the emergence of the shale resource play, the issues of seismic anisotropy have become central, because all shales are seismically anisotropic, whether fractured or not. With the advent of wide-azimuth surveying, it has become apparent that most rocks are azimuthally anisotropic, with P-wave velocities and P-AVO gradients varying with source-receiver azimuth. What this means is that analysis of such data with narrow-azimuth algorithms and concepts will necessarily fail to get the most out of this expensively acquired data. The issues include not only seismic wave propagation, but also seismic rock physics. Isotropic concepts including velocity, Young’s modulus, and Poisson’s ratio have no place in the discussion of anisotropic rocks, unless qualified in some directional way (e.g., vertical Young’s modulus). Likewise, fluid substitution in anisotropic rocks, using the isotropic Biot/Gassmann formula, leads to formal errors, because the bulk modulus does not appear, in a natural way, within the anisotropic P-wave velocity. This updated edition is now current as of 2014.

Download or read book The Effects of Anisotropy on Regional Wave Propagation written by and published by . This book was released on 1997 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crustal rocks can be highly anisotropic, due to (1) oriented minerals (2) oriented cracks, and/or (3) thin layers of material with different elastic stiffnesses. Crustal Love and Rayleigh surface waves couple strongly for anisotropic structures that do not possess a vertical axis of symmetry, and cause explosion to generate significant shear motion on the transverse component 0 seismograms. We developed theory and 1-D layered-media synthetic seismogram codes for anisotropy with an arbitrary axis of symmetry. One code version can synthesize surface waves with periods 100 > T > 0.4 sec. Another code version can synthesize teleseismic body wave reverberations up to 5 Hz. We determined that a tilted axis of symmetry enhances Love-Rayleigh coupling and the scattering of P-waves (compressional) to S-waves (shear). Using P-S scattering, we found evidence for strong (> 10%) anisotropy in the deepest and shallowest crustal layers beneath seismic station ARU (Arti, Russia), an 'open' seismic observatory proximal to the Novaya Zemiya nuclear test site. We also developed a wavelet-base signal processing algorithm that picks out correlated 'signals' from uncorrelated 'noise' in an optimally bandpassed manner Using the Terrascope regional array in California, we applied this algorithm to reconstruct, for a single correlated signal, anomalous amplitudes and polarizations at individual stations, allowing more 'signal' to be recovered than via standard 'stacking'

Download or read book Seismic Signatures and Analysis of Reflection Data in Anisotropic Media written by Ilya Tsvankin and published by SEG Books. This book was released on 2012 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides essential background on anisotropic wave propagation, introduces efficient notation for transversely isotropic (TI) and orthorhombic media, and identifies the key anisotropy parameters for imaging and amplitude analysis. Particular attention is given to moveout analysis and P-wave time-domain processing for VTI and TTI.

Download or read book Fundamentals of Seismic Wave Propagation written by Chris Chapman and published by Cambridge University Press. This book was released on 2004-07-29 with total page 646 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Seismic Wave Propagation, published in 2004, presents a comprehensive introduction to the propagation of high-frequency body-waves in elastodynamics. The theory of seismic wave propagation in acoustic, elastic and anisotropic media is developed to allow seismic waves to be modelled in complex, realistic three-dimensional Earth models. This book provides a consistent and thorough development of modelling methods widely used in elastic wave propagation ranging from the whole Earth, through regional and crustal seismology, exploration seismics to borehole seismics, sonics and ultrasonics. Particular emphasis is placed on developing a consistent notation and approach throughout, which highlights similarities and allows more complicated methods and extensions to be developed without difficulty. This book is intended as a text for graduate courses in theoretical seismology, and as a reference for all academic and industrial seismologists using numerical modelling methods. Exercises and suggestions for further reading are included in each chapter.

Download or read book Applied Seismic Anisotropy written by Colin MacBeth and published by SEG Books. This book was released on 2000 with total page 740 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seismic Anisotropy written by Erling Fjaer and published by . This book was released on 1996 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seismic Wave Propagation in Stratified Media written by Brian Kennett and published by ANU E Press. This book was released on 2009-05-01 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic Wave Propagation in Stratified Media presents a systematic treatment of the interaction of seismic waves with Earth structure. The theoretical development is physically based and is closely tied to the nature of the seismograms observed across a wide range of distance scales - from a few kilometres as in shallow reflection work for geophysical prospecting, to many thousands of kilometres for major earthquakes. A unified framework is presented for all classes of seismic phenomena, for both body waves and surface waves. Since its first publication in 1983 this book has been an important resource for understanding the way in which seismic waves can be understood in terms of reflection and transmission properties of Earth models, and how complete theoretical seismograms can be calculated. The methods allow the development of specific approximations that allow concentration on different seismic arrivals and hence provide a direct tie to seismic observations.

Download or read book Seismic Wave Propagation and Scattering in the Heterogeneous Earth Second Edition written by Haruo Sato and published by Springer Science & Business Media. This book was released on 2012-01-28 with total page 503 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic waves - generated both by natural earthquakes and by man-made sources - have produced an enormous amount of information about the Earth's interior. In classical seismology, the Earth is modeled as a sequence of uniform horizontal layers (or spherical shells) having different elastic properties and one determines these properties from travel times and dispersion of seismic waves. The Earth, however, is not made of horizontally uniform layers, and classic seismic methods can take large-scale inhomogeneities into account. Smaller-scale irregularities, on the other hand, require other methods. Observations of continuous wave trains that follow classic direct S waves, known as coda waves, have shown that there are heterogeneities of random size scattered randomly throughout the layers of the classic seismic model. This book focuses on recent developments in the area of seismic wave propagation and scattering through the randomly heterogeneous structure of the Earth, with emphasis on the lithosphere. The presentation combines information from many sources to present a coherent introduction to the theory of scattering in acoustic and elastic materials and includes analyses of observations using the theoretical methods developed. The second edition especially includes new observational facts such as the spatial variation of medium inhomogeneities and the temporal change in scattering characteristics and recent theoretical developments in the envelope synthesis in random media for the last ten years. Mathematics is thoroughly rewritten for improving the readability. Written for advanced undergraduates or beginning graduate students of geophysics or planetary sciences, this book should also be of interest to civil engineers, seismologists, acoustical engineers, and others interested in wave propagation through inhomogeneous elastic media.

Download or read book Seismic Wave Propagation and Scattering in the Heterogenous Earth written by Haruo Sato and published by Springer Science & Business Media. This book was released on 2008-12-17 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic waves – generated both by natural earthquakes and by man-made sources – have produced an enormous amount of information about the Earth's interior. In classical seismology, the Earth is modeled as a sequence of uniform horizontal layers (or sperical shells) having different elastic properties and one determines these properties from travel times and dispersion of seismic waves. The Earth, however, is not made of horizontally uniform layers, and classic seismic methods can take large-scale inhomogeneities into account. Smaller-scale irregularities, on the other hand, require other methods. Observations of continuous wave trains that follow classic direct S waves, known as coda waves, have shown that there are heterogeneities of random size scattered randomly throughout the layers of the classic seismic model. This book focuses on recent developments in the area of seismic wave propagation and scattering through the randomly heterogeneous structure of the Earth, with emphasis on the lithosphere. The presentation combines information from many sources to present a coherent introduction to the theory of scattering in acoustic and elastic materials and includes analyses of observations using the theoretical methods developed.

Download or read book Modes Rays and Scattering A Basic Study of Seismic Wave Propagation at Regional Distances written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research was to systematically explore the attributes of the wave form Lg and related wave forms which are trapped in the crust. The different theoretical approximations used to characterize or to fully compute regional seismic waves were thoroughly investigated. Empirical classification of the behavior of Lg was achieved through waveform data analyses. The Kennett conjecture that Lg waves can be adequately described by multiple S energy trapped in the crust has been adopted. It has been shown that Lg magnitudes are much more stable than the chaotic behavior of the ray would seem to imply. As a result of recognizing that a large number of caustic are generated as a consequence of the chaotic ray behavior, it was decided that Maslov theory was probably the only suitable technique to deal with the singularity problem. As a result, it has been shown that Maslov synthetics can be used to justify the use of ray density plots as energy plots, which can be used in turn for the calibration of Lg magnitudes. The 3-component array and single station data from the NPE 1993 detonation have been analyzed in order to examine the effects boundary undulations of the crustal wave guide may have on propagation.

Download or read book Seismology and Structure of the Earth written by Barbara Romanowicz and published by Elsevier. This book was released on 2010-04-20 with total page 873 pages. Available in PDF, EPUB and Kindle. Book excerpt: Treatise on Geophysics: Seismology and Structure of the Earth, Volume 1, provides a comprehensive review of the state of knowledge on the Earths structure and earthquakes. It addresses various aspects of structural seismology and its applications to other fields of Earth sciences. The book is organized into four parts. The first part principally covers theoretical developments and seismic data analysis techniques from the end of the nineteenth century until the present, with the main emphasis on the development of instrumentation and its deployment. The second part reviews the status of knowledge on the structure of the Earths shallow layers, starting with a global review of the Earth's crustal structure. The third part focuses on the Earth's deep structure, divided into its main units: the upper mantle, the transition zone and upper-mantle discontinuities, the D region at the base of the mantle, and the Earth's core. The fourth part comprises two chapters which discuss constraints on Earth structure from fields other than seismology: mineral physics and geodynamics. Self-contained volume starts with an overview of the subject then explores each topic with in depth detail Extensive reference lists and cross references with other volumes to facilitate further research Full-color figures and tables support the text and aid in understanding Content suited for both the expert and non-expert

Download or read book Rock Quality Seismic Velocity Attenuation and Anisotropy written by Nick Barton and published by CRC Press. This book was released on 2006-11-03 with total page 729 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic measurements take many forms, and appear to have a universal role in the Earth Sciences. They are the means for most easily and economically interpreting what lies beneath the visible surface. There are huge economic rewards and losses to be made when interpreting the shallow crust or subsurface more, or less accurately, as the case may be.

Download or read book Mantle Convection and Surface Expressions written by Hauke Marquardt and published by John Wiley & Sons. This book was released on 2021-07-07 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multidisciplinary perspective on the dynamic processes occurring in Earth's mantle The convective motion of material in Earth's mantle, powered by heat from the deep interior of our planet, drives plate tectonics at the surface, generating earthquakes and volcanic activity. It shapes our familiar surface landscapes, and also stabilizes the oceans and atmosphere on geologic timescales. Mantle Convection and Surface Expressions brings together perspectives from observational geophysics, numerical modelling, geochemistry, and mineral physics to build a holistic picture of the deep Earth. It explores the dynamic processes occurring in the mantle as well as the associated heat and material cycles. Volume highlights include: Perspectives from different scientific disciplines with an emphasis on exploring synergies Current state of the mantle, its physical properties, compositional structure, and dynamic evolution Transport of heat and material through the mantle as constrained by geophysical observations, geochemical data and geodynamic model predictions Surface expressions of mantle dynamics and its control on planetary evolution and habitability The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.

Download or read book The Core Mantle Boundary Region written by Michael Gurnis and published by American Geophysical Union. This book was released on 1998-02-04 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The two giant heat engines responsible for plate tectonics and the geodynamo dynamically interact at the core-mantle boundary of the Earth's interior. A multidisciplinary approach is required to determine the composition, structure, and dynamics of the interface. This volume describes original and fundamental research in seismology, geodynamics, mineral physics, and geomagnetism.