Download or read book Advancements in 1D and 2D Near surface Seismic Site Characterization Using Surface Waves and Full Waveform Inversion written by Michael Benjamin Schutt Yust and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic site characterization is a critical part of understanding earthquake hazards in geotechnical engineering. This is often accomplished through various invasive and non-invasive methods for measuring shear-wave velocity (Vs) in-situ, as it is directly related to small-strain shear modulus. For civil engineering applications, the seismic conditions of the near surface (top 30 m) are of particular interest. Surface wave testing has become the tool of choice for many engineers due to its flexibility, efficiency, and ability to characterize a wide variety of subsurface conditions. Surface wave testing is also particularly well suited to near-surface imaging due to the prevalence of surface waves within the elastic wavefield at shallow depths. Surface wave testing, however, is not without limitations. Inversion of surface wave dispersion data is ill-posed and non-unique, meaning that when it is performed rigorously with full consideration of epistemic uncertainty, a potentially large number of reasonable and different 1D Vs profiles are produced. This presents a challenge of evaluating which profiles should be used for further analysis or design. Additionally, engineers often desire information about the lateral variability of seismic parameters in the subsurface, but the inherently 1D nature of the processing and inversion techniques used in surface wave testing make acquiring this information challenging. Evaluation of lateral variability is generally accomplished through multiple individual 1D surface wave analyses across the site, providing only pseudo-2D information. This also introduces a new challenge: how to collect the large amount of experimental data required for multiple analyses as the efficiency of traditional surface wave acquisition is limited by the need to physically move geophone arrays with limited numbers of sensors. This dissertation discusses these challenges and presents potential solutions through the application of the DeltaVs method, distributed acoustic sensing, and full waveform inversion
Download or read book Near surface Characterization Via Seismic Surface wave Inversion written by Soumya Roy and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Characterization of the near-surface is important in identifying shallow properties and structures. In this dissertation, special emphasis is placed on estimating near-surface shear (S)-wave velocities (V_S) which can be used for exploration seismology as well as geotechnical purposes; and even for planetary studies. A frequency-based surface-wave (Rayleigh-wave or ground-roll) inversion method (MASW: Multichannel Analysis of Surface Waves) has been used to estimate 1D and 2D S-wave velocities. The method has been applied on varied seismic datasets related to numerical modeling, physical modeling, and field surveys. The field seismic datasets are from different geological settings and geographical locations: 1) La Marque, Texas, 2) Barringer (Meteor) Crater, Arizona, 3) YBRA field camp, Montana, 4) Hockley fault survey, Texas, and 5) Bradford, Pennsylvania. Estimated S-wave velocities range from as low as 100-300 m/s (La Marque, Hockley) to as high as 3400-3500 m/s (physical model: blank glass block). For the Meteor Crater survey, an unconsolidated near-surface structure (ejecta-blanket) and its thinning thickness trend (thickness decreasing from 20 m to 5 m) has been successfully identified using 2D V_S structure (400-1200 m/s). The depths of investigation for S-wave velocities vary from only 10 m (Hockley survey) to 180 m (Bradford survey) depending on acquisition geometries and source types. Apart from the identification of geological structures; S-wave velocities have been used to calculate S-wave statics and predict densities. The long-wavelength S-wave statics have been calculated for Bradford and Meteor Crater surveys. The densities have been successfully predicted from V_S for modeling experiments and field data (Bradford and YBRA surveys). All predicted densities are consistent with known values with a maximum error of 6%. The effect of lateral heterogeneity on MASW has also been evaluated using different numerical and physical models (dipping layers varying from 10℗ð to 90℗ð). MASW works well for gentle heterogeneity but provides smeared velocity structures for sharp heterogeneities (physical model experiment and Hockley fault survey). A basic full-waveform inversion scheme has been applied on a numerical model with a vertical interface (i.e. 90℗ð dip) showing its potential to handle lateral heterogeneity problems.
Download or read book Surface Wave Analysis for Near Surface Applications written by Giancarlo Dal Moro and published by Elsevier. This book was released on 2014-11-04 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seismic Wave Analysis for Near Surface Applications presents the foundational tools necessary to properly analyze surface waves acquired according to both active and passive techniques. Applications range from seismic hazard studies, geotechnical surveys and the exploration of extra-terrestrial bodies. Surface waves have become critical to near-surface geophysics both for geotechnical goals and seismic-hazard studies. Included in this book are the related theories, approaches and applications which the lead editor has assembled from a range of authored contributions carefully selected from the latest developments in research. A unique blend of theory and practice, the book’s concepts are based on exhaustive field research conducted over the past decade from the world’s leading seismologists and geophysicists. Edited by a geophysicist with nearly 20 years of experience in research, consulting, and geoscience software development Nearly 100 figures, photographs, and examples aid in the understanding of fundamental concepts and techniques Presents the latest research in seismic wave characteristics and analysis, the fundamentals of signal processing, wave data acquisition and inversion, and the latest developments in horizontal-to-vertical spectral ratio (HVSR) Each chapter features a real-world case study—13 in all—to bring the book’s key principles to life
Download or read book The Microtremor Survey Method written by Hiroshi Okada and published by SEG Books. This book was released on 2003 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes the nature of the microtremor noise field, the use of appropriate surface arrays of geophones, and the two principal classes of array-processing techniques, high-resolution beamforming and the spatial autocorrelation method (SPAC). This is the first comprehensive textbook of the microtremor survey method written in English.
Download or read book Surface Wave Methods for Near Surface Site Characterization written by Sebastiano Foti and published by CRC Press. This book was released on 2014-08-25 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface wave methods analysis the dispersive nature of surface wave propagation in heterogeneous media to measure shear wave velocity or material damping ratio profiles, and enable earthquake site response to be assessed. This is the only comprehensive reference that provides a unified treatment of surface wave propagation, signal processing, inverse theory and the testing protocols that form the basis of modern surface wave methods. The use of these tests has increased dramatically since the 1980s, but they are too often performed and interpreted in a variety of ways that are confusing. This book answers the pressing need for a guide to the basic principles as well as outlining a set of reliable, dependable and accepted practices. It is written for geotechnical engineers, engineering seismologists and geophysicists as well as academics in these fields.
Download or read book Inversion of Surface Waves in an Oil and Gas Exploration Context written by Isabella Masoni and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The characterization of the near surface is an important topic for the oil and gas industry. For land and Ocean Bottom Cable (OBC) acquisitions, weathered or unconsolidated top layers, prominent topography and complex shallow structures may make imaging at target depth very difficult. Energetic and complex surface waves often dominate such recordings, masking the signal and challenging conventional seismic processing. Static corrections and the painstaking removal of surface waves are required to obtain viable exploration information.Yet surface waves, which sample the near surface region, are considered as signal on both the engineering and geotechnical scale as well as the global seismology scale. Their dispersive property is conventionally used in surface wave analysis techniques to obtain local shear velocity depth profiles. But limitations such as the picking of dispersion curves and poor lateral resolution have lead to the proposal of Full Waveform Inversion (FWI) as an alternative high resolution technique. FWI can theoretically be used to explain the complete waveforms recoded in seismograms, but FWI with surface waves has its own set of challenges. A sufficiently accurate initial velocity model is required or otherwise cycle-skipping problems will prevent the inversion to converge.This study investigates alternative misfit functions that can overcome cycle-skipping and decrease the dependence on the initial model required. Computing the data-fitting in different domains such as the frequency-wavenumber (f-k) and frequency-slowness (f-p) domains is proposed for robust FWI, and successful results are achieved with a synthetic dataset, in retrieving lateral shear velocity variations.In the second part of this study a FWI layer stripping strategy, specifically adapted to the physics of surface waves is proposed. The penetration of surface waves is dependent on their wavelength, and therefore on their frequency. High-to-low frequency data is therefore sequentially inverted to update top-to-bottom layer depths of the shear velocity model. In addition, near-to-far offsets are considered to avoid cycle-skipping issues. Results with a synthetic dataset show that this strategy is more successful than conventional multiscale FWI in using surface waves to update the shear velocity model.Finally inversion of surface waves for near surface characterization is attempted on a real dataset at the oil and gas exploration scale. The construction of initial models and the difficulties encountered during FWI with real data are discussed.
Download or read book Near Surface Site Characterization Using 3 d Full Waveform Tomography written by Trung Dung Nguyen and published by . This book was released on 2017 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Integration of Surface Seismic Waves Laboratory Measurements and Downhole Acoustic Televiewer Imaging in Geotechnical Characterization written by Amelia Erin Fader and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Geotechnical site characteristics are a function of the subsurface elastic moduli and the geologic structures. This study integrates borehole, surface and laboratory measurements for a geotechnical investigation that is focused on investigating shear-wave velocity (Vs) variation and its implication to geotechnical aspects of the Ogden test site in eastern Kansas. The area has a potential of seismicity due to the seismic zone associated with the Nemaha formation where earthquakes pose a moderate hazard. This study is in response to recent design standards for bridge structures require integrating comprehensive geotechnical site characterization. Furthermore, evaluation of dynamic soil properties is important for proper seismic response analysis and soil modeling programs. In this study, near surface geophysical site characterization in the form of 2D shear-wave velocity (Vs) structure that is compared with laboratory measurements of elastic moduli and earth properties at simulated in situ overburden pressure conditions and synergy with downhole Acoustic Televiewer time and amplitude logs, proved very robust "validated" workflow in site characterization for geotechnical purposes. An important component of a geotechnical site characterization is the evaluation of in-situ shear modulus, Poisson's ratio and reliable and accurate elastic modulus ([lambda]) and shear modulus ([mu]) estimates are important in a good geotechnical site characterization. The geophysical site characterization, undertaken in this study, will complement and help in extrapolating drilling and core-based properties deduced by the geotechnical engineers interested at the test site.
Download or read book New Methods for Engineering Site Characterization Using Reflection and Surface Wave Seismic Surveys written by Susit Chaiprakaikeow and published by . This book was released on 2012 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: PUBLIC ABSTRACT: This study presents two new seismic testing methods for engineering application, a new shallow seismic reflection method and Time Filtered Analysis of Surface Waves (TFASW). Both methods are described in this dissertation. The new shallow seismic reflection was developed to measure reflections at a single point using 2-4 receivers, assuming homogeneous, horizontal layering. Two problems commonly encountered in reflection testing are dealt with in this new method. These problems are: phase shifts between the wave source and ground motion; and, loss of high frequency energy. Using approaches to mitigate these problems significantly improved the shape of measured waveforms. However, none of the sites investigated yielded strong enough reflectors to fully characterize the sites. TFASW is a new surface (Rayleigh) wave method to determine the shear wave velocity profile at soil and rock sites. The method is an improvement over other surface wave seismic methods because digital filters with optimized bandwidths are used to characterize the surface wave dispersion. Successful applications of the TFASW method are shown at three sites.
Download or read book An Integrated Study of Full Wave field Seismic Site Characterization Techniques written by David Craig Pearson and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book IS TOKYO 95 written by Kohji Tokimatsu and published by . This book was released on 1995* with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Full Seismic Waveform Modelling and Inversion written by Andreas Fichtner and published by Springer Science & Business Media. This book was released on 2010-11-16 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent progress in numerical methods and computer science allows us today to simulate the propagation of seismic waves through realistically heterogeneous Earth models with unprecedented accuracy. Full waveform tomography is a tomographic technique that takes advantage of numerical solutions of the elastic wave equation. The accuracy of the numerical solutions and the exploitation of complete waveform information result in tomographic images that are both more realistic and better resolved. This book develops and describes state of the art methodologies covering all aspects of full waveform tomography including methods for the numerical solution of the elastic wave equation, the adjoint method, the design of objective functionals and optimisation schemes. It provides a variety of case studies on all scales from local to global based on a large number of examples involving real data. It is a comprehensive reference on full waveform tomography for advanced students, researchers and professionals.
Download or read book Geotechnical Site Characterization Using Multi channel Analysis of Rayleigh and Love Waves written by James David Lane and published by . This book was released on 2009 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Multi-Channel Analysis of Surface Waves (MASW) is a technique in which surface waves can be analyzed to determine soil shear wave velocity profiles with depth. The shear wave velocity of soil can be used to calculate the shear modulus, which is an important geotechnical engineering parameter. Site surveys were conducted and analyzed located at a location on the flood plain of the Tennessee River. The flood plain consists of a thin layer of soil above rigid (Knox Dolomite) bedrock and exhibited strong stratification. Three different aspects of MASW data acquisition and analysis are presented in the study. The first aspect is the response correction of the classical horizontal and vertical component geophone and its effects on surface wave dispersion; the second aspect is the effect of Rayleigh wave MASW data acquisition, analysis, and modeling as influenced by Rayleigh wave guides; the third aspect is the use of MASW and Love wave data acquisition, analysis, and modeling. MASW is performed using a seismic source and geophones (velocity sensor) without correcting the amplitude and phase errors induced by the equivalent single degree of freedom response function representing the mechanical response of a given velocity sensor. Geophones were experimentally tested in the laboratory to determine their natural frequency, damping ratio, and transduction constants. The results from these tests were mathematically corrected for their mechanical response and compared to uncorrected and corrected field data. Several seismic sources and various sourceoffset distances were evaluated to determine their effects on Rayleigh wave dispersion. Rayleigh waves, guided in a layer, were interpreted to have a profound influence on the Rayleigh wave dispersion data obtained using different seismic sources and source-offset distances. Results from Love wave data analysis produced superior dispersion data in comparison to the dispersion data obtained from Rayleigh wave data, making interpretation much more certain.
Download or read book Near surface Characterization Using Seismic Refraction and Surface wave Methods written by Khaled Al Dulaijan and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The use of surface waves for site characterization and seismic hazard analysis written by Valerio Poggi and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismic Site Characterization Techniques Applied to the NATO RSG 11 Test Site in M nster Nord Federal Republic of Germany written by Donald G. Albert and published by . This book was released on 1982 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Optimization written by Joseph-Frédéric Bonnans and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book starts with illustrations of the ubiquitous character of optimization, and describes numerical algorithms in a tutorial way. It covers fundamental algorithms as well as more specialized and advanced topics for unconstrained and constrained problems. This new edition contains computational exercises in the form of case studies which help understanding optimization methods beyond their theoretical description when coming to actual implementation.
