Download or read book Double Difference Earthquake Relocation After Full Waveform Discrimination written by Prabhat Shrestha and published by . This book was released on 2015 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: The estimation of the hypocentres of seismic events is crucial in the interpretation of subsurface structure and tectonics. The principle objective was to refine estimates of these hypocentres by analysing the full seismic wave field - rather than the P or P and S waves alone - of a cluster of events. The events we examine were originally located using their P and S wave arrivals on borehole seismometers, as part of a CO2 sequestration project from the Aneth Oil field in Utah, USA. These events were then clustered based on their P wave similarity alone. We further sub-clustered these events based on their full waveform. Similar results were obtained from the full-waveform analysis in both time and frequency domains. We then compared earthquake relocation based on double-difference tomography of the original cluster, and relocation of the events, per sub-cluster. The double difference algorithm was applied in software package HypoDD. Six sub-clusters arose from the full waveform analysis on a possible "en echelon" structure with a north-west south-east alignment. Total-cluster relocations converged to the centroid of this cluster; these hypocentre locations were deemed less likely than the original locations, given prior knowledge of the geology. However, relocations were more refined when HypoDD was run for individual clusters. Individual cluster relocations appeared to condense within their sub-cluster centroid, the pre-processing step of sub-clustering retained en echelon structure and the north-west southeast alignment, preserving spatial information. This supports our assumption that the initial locations identified using correlated P arrivals were accurate at the outset. HypoDD's inability to accept negative station elevations in conjunction with a layered velocity model prompted us to shift the station and event locations above the surface. The presence of a low velocity zone also prompted the adjustment of the velocity model such that this zone was eradicated. This was achieved by adjusting the velocity model such that the velocity increased in conjunction with the depth throughout. Shifting the location of the earthquakes above the surface may have affected our hypocentre relocations but our epicentre relocation accuracy was kept intact. Our alteration of the geological structure through the adjustment of the low velocity zone may have also affected our hypocentre locations. However, our aims of witnessing the sub-clusters converge while keeping their en echelon structure and north-west south-east alignment was fulfilled. This suggests that the errors which originate from these approximations were minimal. The application of the double difference algorithm on a known sub-cluster at a CO2 sequestration project at Aneth field refines the location of epicentre estimations, but maintains the structure of fault systems hidden in the full seismic waveforms. In the future, further knowledge of the subsurface will allow us to better reconstruct the low velocity zone. This may result in more refined epicentre and hypocentre relocations. These newly found locations could be mapped with known fault structures, in order to find new fault regimes within these structures.
Download or read book Parameter Estimation and Inverse Problems written by Richard C. Aster and published by Elsevier. This book was released on 2018-10-16 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: Parameter Estimation and Inverse Problems, Third Edition, is structured around a course at New Mexico Tech and is designed to be accessible to typical graduate students in the physical sciences who do not have an extensive mathematical background. The book is complemented by a companion website that includes MATLAB codes that correspond to examples that are illustrated with simple, easy to follow problems that illuminate the details of particular numerical methods. Updates to the new edition include more discussions of Laplacian smoothing, an expansion of basis function exercises, the addition of stochastic descent, an improved presentation of Fourier methods and exercises, and more. - Features examples that are illustrated with simple, easy to follow problems that illuminate the details of a particular numerical method - Includes an online instructor's guide that helps professors teach and customize exercises and select homework problems - Covers updated information on adjoint methods that are presented in an accessible manner
Download or read book Analysis of Seismic Source Characteristics Across A Broad Range Of Spatial Scales written by Chanel Deane and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the abundance of global seismic waveform data across a broad range of temporal and spatial scales, ample opportunities exist to investigate seismic source and propagation effects. In this dissertation, I present results from three inductive, observation-driven analyses that exploit local-to-teleseismic distance seismic observations to explore seismic source characteristics across a broad range of spatial scales. Each investigation emphasized one or more seismological challenges that remain despite advances in global instrumentation, source characterization approaches, and seismic wave propagation modeling. For the first investigation, we exploited local-distance P- and S-wave observations generated by mining-related and small-magnitude events at a gold mine in South Africa to explore the robustness of P-to-S-wave amplitude ratios. P/S amplitude ratios are traditionally used in discrimination studies between earthquakes and explosions recorded at regional and teleseismic distances (greater than 200km). Fewer studies have explored the variability of P/S amplitude ratios using data recorded at local distances, distances less than 200 km, where more scrutiny of wave propagation, near-surface geology, and source and strain release patterns are required. We took advantage of the dense seismic network at the Klerksdorp mine to investigate the variability of low-yield earthquake and mining-related event P/S amplitude ratios at local distances. Our results showed that most locally recorded low-magnitude events in the Klerksdorp region have comparable shear-wave energy to low-magnitude earthquakes. Our time-domain rms-based measurement of P and S amplitudes resulted in stable event average P/S ratios that are likely separate from explosive sources. We used the observations to demonstrate the expected variability of the ratios with smaller seismic networks (3-, 5-, 7-station) to show the amplitude ratios remained relatively stable across a bandwidth of 1-30 Hz, but ratio variability decreased with increasing station number. In the second investigation, we conducted an earthquake relocation study of moderate-to-large magnitude events along the Southwest Indian Ridge (SWIR) from 1990 to 2022 using global surface wave observations. Earthquake locations are essential parameters used in seismology to investigate earthquake processes, tectonics, and the subsurface. Although seismologists have constrained the location of an earthquake reasonably well using arrival-time measurements, important tectonic regions, such as mid-ocean ridges (MOR), remain less well-constrained because of the lack of nearby seismic stations. We leveraged an existing surface-wave relative relocation approach to estimate precise relative locations along the SWIR, investigate updated seismicity patterns, and relate those patterns to tectonic processes occurring along the ultra-slow-to-slow spreading ridge system. To handle the large data set from a broad region we used an artificial neural network to identify the highest-quality observations and reduce the computational burden associated with cross-correlating millions of surface waveforms. Our results show a 3-second reduction in location misfit and precise locations well within 5 km of bathymetric features demonstrating the ability to use global surface-wave observations to improve the precision of earthquake locations in a remote region. We observed (with greater clarity) many expected general tectonic patterns including single- and multiple strands active along transform faults, the gradual transition from normal to strike-slip faulting along ridge-transform intersections, clustering of normal-faulting along the ridge segments (including doublet and multiplet sequences), occasional migration of events along transforms and ridge segments, and clustering of events around ridge volcanoes or regions of unusual bathymetry. For the final investigation, we utilized abundant mining-related seismic events that occur each year in Pennsylvania and the wealth of local to regional seismic networks to evaluate short-period seismic-wave propagation across the region. Pennsylvania hosts many industrial seismic events and experiences a small number of naturally-occurring earthquakes, but industrial seismic sources are currently excluded in the generation of ground motion prediction equations. We performed a linear regression of peak ground-velocity measurements for industrial explosions in Pennsylvania. We examined the data across a frequency band from 1 to 16 Hz, but the best results with the most observations were those from the 1-2 Hz band. The results show that the small-magnitude explosion data are unable to resolve differences in simple models of the decrease in amplitude with distance. But the results demonstrate that applying the geometric spreading corrections used for magnitude estimates across the eastern US is reasonable for the short distances used to estimate the size of small mining events across the region. Regression produced a set of relative source sizes that exhibit a complicated relationship with locally estimated magnitudes. The difference between regression estimated source size and traditional analyst-based magnitudes correlates with local magnitude. Careful examination of the data suggested that observations from greater distance are hard to screen using signal-to-noise measurements and simple magnitude-dependent distance cutoff relationships. Thus, the traditional approach to magnitude estimation that relies on human or AI-expert-trained systems to separate signal and noise remains important, especially for the smaller events.
Download or read book Advances in Seismic Event Location written by Cliffort H. Thurber and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Seismic Event Location provides a broad overview of the fundamental issues involved in seismic event location, and presents a variety of state-of-the-art location methods and applications at a wide range of spatial scales. Three important themes in the book are: seismic monitoring for a Comprehensive Nuclear-Test-Ban Treaty (CTBT), seismic event location in three-dimensional Earth models, and methods for multiple-event location. Each chapter contains background material to help readers less familiar with the topics covered, as well as to provide abundant references for readers interested in probing deeper into a topic. However, most of the emphasis is on recent advances in methodology and their application. Audience: The book is intended primarily for academic and professional researchers and graduate students in seismology.
Download or read book Imaging the Rupture Processes of Earthquakes Using the Relative Back Projection Method written by Hao Zhang and published by Springer. This book was released on 2017-12-27 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis adopts the relative back-projection method to dramatically reduce “swimming” artifacts by identifying the rupture fronts in the time window of a reference station; this led to a faster and more accurate image of the rupture processes of earthquakes. Mitigating the damage caused by earthquakes is one of the primary goals of seismology, and includes saving more people’s lives by devising seismological approaches to rapidly analyze an earthquake’s rupture process. The back-projection method described in this thesis can make that a reality.
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 Developments in Ground Control in Mining 1981 2020 written by Syd S. Peng and published by Society for Mining, Metallurgy & Exploration. This book was released on 2022-06-03 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: The best of ground control technology, 40 years in the making. Developments in Ground Control summarizes the objectives, methodology used, and major conclusions reached from papers presented and published in the International Conference on Ground Control in Mining (ICGCM) proceedings from 1981 to 2020. Because the subject areas of the papers published in the proceedings are so broad, ranging from accident training and coal/rock bursts to geology, pillar, multiseam mining, in situ stresses, roof falls, and roof supports to surface subsidence, the papers were grouped into 13 aggregate topics and addressed separately in 13 book chapters by 13 authors from 4 countries. These book chapters are a fresh look at the topics, providing new insights, sourcing older papers, and summarizing data. This is an enormous help for those seeking information on ground control. There were 1,795 papers in the 40 years of ICGCM proceedings in more than 40 ground control topical areas. It would certainly be very time consuming if not impossible to find the right papers of interest in a timely manner. This book makes it easy for interested people to find the progress, application, and achievements of certain techniques from the past 40 years and how they affected the field of ground control and the world mining industry, in particular, the United States. Generally speaking, most researchers tend to favor recent developments when performing a literature search, ignoring or considering old papers outdated. In contrast, over the last 40 years, most research findings for a specific topic in ICGCM received continuing attention for subsequent development or repeated citations if applications were successful.
Download or read book Encyclopedia of Geology written by and published by Academic Press. This book was released on 2020-12-16 with total page 5634 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encyclopedia of Geology, Second Edition presents in six volumes state-of-the-art reviews on the various aspects of geologic research, all of which have moved on considerably since the writing of the first edition. New areas of discussion include extinctions, origins of life, plate tectonics and its influence on faunal provinces, new types of mineral and hydrocarbon deposits, new methods of dating rocks, and geological processes. Users will find this to be a fundamental resource for teachers and students of geology, as well as researchers and non-geology professionals seeking up-to-date reviews of geologic research. Provides a comprehensive and accessible one-stop shop for information on the subject of geology, explaining methodologies and technical jargon used in the field Highlights connections between geology and other physical and biological sciences, tackling research problems that span multiple fields Fills a critical gap of information in a field that has seen significant progress in past years Presents an ideal reference for a wide range of scientists in earth and environmental areas of study
Download or read book Complexity of Seismic Time Series written by Tamaz Chelidze and published by Elsevier. This book was released on 2018-05-21 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complexity of Seismic Time Series: Measurement and Application applies the tools of nonlinear dynamics to seismic analysis, allowing for the revelation of new details in micro-seismicity, new perspectives in seismic noise, and new tools for prediction of seismic events. The book summarizes both advances and applications in the field, thus meeting the needs of both fundamental and practical seismology. Merging the needs of the classical field and the very modern terms of complexity science, this book covers theory and its application to advanced nonlinear time series tools to investigate Earth's vibrations, making it a valuable tool for seismologists, hazard managers and engineers. - Covers the topic of Earth's vibrations involving many different aspects of theoretical and observational seismology - Identifies applications of advanced nonlinear time series tools for the characterization of these Earth's signals - Merges the needs of geophysics with the applications of complexity theory - Describes different methodologies to analyze problems, not only in the context of geosciences, but also those associated with different complex systems across disciplines
Download or read book Routine Data Processing in Earthquake Seismology written by Jens Havskov and published by Springer Science & Business Media. This book was released on 2010-06-16 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this book is to get a practical understanding of the most common processing techniques in earthquake seismology. The book deals with manual methods and computer assisted methods. Each topic will be introduced with the basic theory followed by practical examples and exercises. There are manual exercises entirely based on the printed material of the book, as well as computer exercises based on public domain software. Most exercises are computer based. The software used, as well as all test data are available from http://extras.springer.com. This book is intended for everyone processing earthquake data, both in the observatory routine and in connection with research. Using the exercises, the book can also be used as a basis for university courses in earthquake processing. Since the main emphasis is on processing, the theory will only be dealt with to the extent needed to understand the processing steps, however references will be given to where more extensive explanations can be found. Includes: • Exercises • Test data • Public domain software (SEISAN) available from http://extras.springer.com
Download or read book Seismological Research Letters written by and published by . This book was released on 2006 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geophysics and Geosequestration written by Thomas L. Davis and published by Cambridge University Press. This book was released on 2019-05-09 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: An overview of the geophysical techniques and analysis methods for monitoring subsurface carbon dioxide storage for researchers and industry practitioners.
Download or read book The Seismic Analysis Code written by George Helffrich and published by Cambridge University Press. This book was released on 2013-09-19 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first comprehensive guide to SAC, complete with introductory materials and detailed descriptions of its most advanced features.
Download or read book Moment Tensor Solutions written by Sebastiano D'Amico and published by Springer. This book was released on 2018-05-12 with total page 751 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book first focuses on the explanation of the theory about focal mechanisms and moment tensor solutions and their role in the modern seismology. The second part of the book compiles several state-of-the-art case studies in different seismotectonic settings of the planet.The assessment of seismic hazard and the reduction of losses due to future earthquakes is probably the most important contribution of seismology to society. In this regard, the understanding of reliable determination seismic source and of its uncertainty can play a key role in contributing to geodynamic investigation, seismic hazard assessment and earthquake studies. In the last two decades, the use of waveforms recorded at local-to-regional distances has increased considerably. Waveform modeling has been used also to estimate faulting parameters of small-to-moderate sized earthquakes.
Download or read book Tectonic Geomorphology written by Douglas W. Burbank and published by John Wiley & Sons. This book was released on 2011-11-02 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tectonic geomorphology is the study of the interplay between tectonic and surface processes that shape the landscape in regions of active deformation and at time scales ranging from days to millions of years. Over the past decade, recent advances in the quantification of both rates and the physical basis of tectonic and surface processes have underpinned an explosion of new research in the field of tectonic geomorphology. Modern tectonic geomorphology is an exceptionally integrative field that utilizes techniques and data derived from studies of geomorphology, seismology, geochronology, structure, geodesy, stratigraphy, meteorology and Quaternary science. While integrating new insights and highlighting controversies from the ten years of research since the 1st edition, this 2nd edition of Tectonic Geomorphology reviews the fundamentals of the subject, including the nature of faulting and folding, the creation and use of geomorphic markers for tracing deformation, chronological techniques that are used to date events and quantify rates, geodetic techniques for defining recent deformation, and paleoseismologic approaches to calibrate past deformation. Overall, this book focuses on the current understanding of the dynamic interplay between surface processes and active tectonics. As it ranges from the timescales of individual earthquakes to the growth and decay of mountain belts, this book provides a timely synthesis of modern research for upper-level undergraduate and graduate earth science students and for practicing geologists. Additional resources for this book can be found at: www.wiley.com/go/burbank/geomorphology.
Download or read book The 1940 Vrancea Earthquake Issues Insights and Lessons Learnt written by Radu Vacareanu and published by Springer. This book was released on 2016-03-02 with total page 511 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings include most of the available information on this major seismic event and its consequences. With an estimated moment magnitude of 7.7 and a heavy toll in terms of human and economic losses, it ranks as the largest intermediate-depth earthquake in Europe in the twentieth century. Nevertheless, because of the difficult conditions in the 1940s, the lessons learnt after the Vrancea earthquake were not extensively shared with the international scientific community and thus, this book fills a gap in the literature discussing the knowledge acquired after major disasters. Past experience together with current understanding of the 1940 Vrancea earthquake are presented along with the latest information on Romanian seismicity, seismic hazard and risk assessment, and seismic evaluation and rehabilitation of buildings and structures. Moreover, it includes excerpts from Romanian post-disaster reports and textbooks concerning the earthquake.
Download or read book Geophysics Tectonics Abstracts written by and published by . This book was released on 1985 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:
