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 Seismic Surface Waves in a Laterally Inhomogeneous Earth written by V.I. Keilis-Borok and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface waves form the longest and strongest portion of a seismic record excited by explosions and shallow earthquakes. Traversing areas with diverse geologic structures, they 'absorb' information on the properties of these areas which is best retlected in dispersion, the dependence of velocity on frequency. The other prop erties of these waves - polarization, frequency content, attenuation, azimuthal variation of the amplitude and phase - arc also controlled by the medium between the source and the recording station; some of these are affected by the properties of the source itself and by the conditions around it. In recent years surface wave seismology has become an indispensable part of seismological practice. The maximum amplitude in the surface wave train of virtually every earthquake or major explosion is being measured and used by all national and international seismological surveys in the determination of the most important energy parameter of a seismic source, namely, the magnitude M,. The relationship between M, and the body wave magnitude fI1t, is routinely employed in identification of underground nuclear explosions. Surface waves of hundreds of earthquakes recorded every year are being analysed to estimate the seismic moment tensor of earthquake sources, to determine the periods of free oscillations of the Earth, to construct regional dispersion curves from which in turn the crustal and upper mantle structure in various areas is derived, and to evaluate the dissipative parameters of the mantle material.
Download or read book Seismic Geomorphology written by R. J. Davies and published by Geological Society of London. This book was released on 2007 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: We are poised to embark on a new era of discovery in the study of geomorphology. The discipline has a long and illustrious history, but in recent years an entirely new way of studying landscapes and seascapes has been developed. It involves the use of 3D seismic data. Just as CAT scans allow medical staff to view our anatomy in 3D, seismic data now allows Earth scientists to do what the early geomorphologists could only dream of - view tens and hundreds of square kilometres of the Earth's subsurface in 3D and therefore see for the first time how landscapes have evolved through time. This volume demonstrates how Earth scientists are starting to use this relatively new tool to study the dynamic evolution of a range of sedimentary environments.
Download or read book Land Seismic Source Study Vibrator source characteristics from downhole measurements An analysis of three component walk away noise test data for different land seismic sources Land seismic source study analysis and comparison of reflection spread measurement written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Treatise on Geophysics written by and published by Elsevier. This book was released on 2015-04-17 with total page 5604 pages. Available in PDF, EPUB and Kindle. Book excerpt: Treatise on Geophysics, Second Edition, is a comprehensive and in-depth study of the physics of the Earth beyond what any geophysics text has provided previously. Thoroughly revised and updated, it provides fundamental and state-of-the-art discussion of all aspects of geophysics. A highlight of the second edition is a new volume on Near Surface Geophysics that discusses the role of geophysics in the exploitation and conservation of natural resources and the assessment of degradation of natural systems by pollution. Additional features include new material in the Planets and Moon, Mantle Dynamics, Core Dynamics, Crustal and Lithosphere Dynamics, Evolution of the Earth, and Geodesy volumes. New material is also presented on the uses of Earth gravity measurements. This title is essential for professionals, researchers, professors, and advanced undergraduate and graduate students in the fields of Geophysics and Earth system science. Comprehensive and detailed coverage of all aspects of geophysics Fundamental and state-of-the-art discussions of all research topics Integration of topics into a coherent whole
Download or read book Living on an Active Earth written by National Research Council and published by National Academies Press. This book was released on 2003-09-22 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: The destructive force of earthquakes has stimulated human inquiry since ancient times, yet the scientific study of earthquakes is a surprisingly recent endeavor. Instrumental recordings of earthquakes were not made until the second half of the 19th century, and the primary mechanism for generating seismic waves was not identified until the beginning of the 20th century. From this recent start, a range of laboratory, field, and theoretical investigations have developed into a vigorous new discipline: the science of earthquakes. As a basic science, it provides a comprehensive understanding of earthquake behavior and related phenomena in the Earth and other terrestrial planets. As an applied science, it provides a knowledge base of great practical value for a global society whose infrastructure is built on the Earth's active crust. This book describes the growth and origins of earthquake science and identifies research and data collection efforts that will strengthen the scientific and social contributions of this exciting new discipline.
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 A Vision for NSF Earth Sciences 2020 2030 written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2020-08-31 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Earth system functions and connects in unexpected ways - from the microscopic interactions of bacteria and rocks to the macro-scale processes that build and erode mountains and regulate Earth's climate. Efforts to study Earth's intertwined processes are made even more pertinent and urgent by the need to understand how the Earth can continue to sustain both civilization and the planet's biodiversity. A Vision for NSF Earth Sciences 2020-2030: Earth in Time provides recommendations to help the National Science Foundation plan and support the next decade of Earth science research, focusing on research priorities, infrastructure and facilities, and partnerships. This report presents a compelling and vibrant vision of the future of Earth science research.
Download or read book Earthquakes and Multi hazards Around the Pacific Rim Vol I written by Yongxian Zhang and published by Birkhäuser. This book was released on 2017-12-20 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first of two volumes devoted to earthquakes and multi-hazards around the Pacific Rim. The circum-Pacific seismic belt is home to roughly 80% of the world’s largest earthquakes, making it the ideal location for investigating earthquakes and related hazards such as tsunamis and landslides. Gathering 16 papers that cover a range of topics related to multi-hazards, the book is divided into three sections: earthquake physics, earthquake simulation and data assimilation, and multi-hazard assessment and earthquake forecasting models. The first section includes papers on laboratory-derived rheological parameters as well as seismic studies in the Gulf of California and China. In turn, the second section includes papers on improvements in earthquake simulators as well as the statistical methods used to evaluate their performance, automated methods for determining fault slip using near-field interferometric data, variabilities in earthquake stress drops in California, and the use of social media data to supplement physical sensor data when estimating local earthquake intensity. The final section includes a paper on probabilistic tsunami hazard assessment, several papers on time-dependent seismic hazard analysis around the Pacific Rim, and a paper on induced and triggered seismicity at the Geysers geothermal field in California. Rapid advances are being made in our understanding of multi-hazards, as well as the range of tools used to investigate them. This volume provides a representative cross-section of how state-of-the-art knowledge and tools are currently being applied to multi-hazards around the Pacific Rim. The material here should be of interest to scientists involved in all areas of multi-hazards, particularly seismic and tsunami hazards. In addition, it offers a valuable resource for students in the geosciences, covering a broad spectrum of topics related to hazard research.
Download or read book U S Geological Survey Circular written by and published by . This book was released on 1984 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Strong Motion Program Report January December 1985 written by and published by . This book was released on 1989 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laurentia written by Steven J. Whitmeyer and published by Geological Society of America. This book was released on 2023-01-04 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This Memoir focuses on 7 'turning points' that had specific and lasting impacts on Laurentian evolution: The Neoarchean, characterized by cratonization; the Paleoproterozoic and the initial assembly of Laurentia; the Mesoproterozoic southern margin of Laurentia; the Midcontinent rift and the Grenville orogeny; (5) the Neoproterozoic breakup of Rodinia; the mid-Paleozoic phases of the Appalachian-Caledonian orogen; and the Jurassic-Paleogene assembly of the North American Cordillerar"--
Download or read book Numerical Methods in Geotechnical Engineering IX written by António S. Cardoso and published by CRC Press. This book was released on 2018-06-19 with total page 2563 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical Methods in Geotechnical Engineering IX contains 204 technical and scientific papers presented at the 9th European Conference on Numerical Methods in Geotechnical Engineering (NUMGE2018, Porto, Portugal, 25—27 June 2018). The papers cover a wide range of topics in the field of computational geotechnics, providing an overview of recent developments on scientific achievements, innovations and engineering applications related to or employing numerical methods. They deal with subjects from emerging research to engineering practice, and are grouped under the following themes: Constitutive modelling and numerical implementation Finite element, discrete element and other numerical methods. Coupling of diverse methods Reliability and probability analysis Large deformation – large strain analysis Artificial intelligence and neural networks Ground flow, thermal and coupled analysis Earthquake engineering, soil dynamics and soil-structure interactions Rock mechanics Application of numerical methods in the context of the Eurocodes Shallow and deep foundations Slopes and cuts Supported excavations and retaining walls Embankments and dams Tunnels and caverns (and pipelines) Ground improvement and reinforcement Offshore geotechnical engineering Propagation of vibrations Following the objectives of previous eight thematic conferences, (1986 Stuttgart, Germany; 1990 Santander, Spain; 1994 Manchester, United Kingdom; 1998 Udine, Italy; 2002 Paris, France; 2006 Graz, Austria; 2010 Trondheim, Norway; 2014 Delft, The Netherlands), Numerical Methods in Geotechnical Engineering IX updates the state-of-the-art regarding the application of numerical methods in geotechnics, both in a scientific perspective and in what concerns its application for solving practical boundary value problems. The book will be much of interest to engineers, academics and professionals involved or interested in Geotechnical Engineering.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-06 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Earth s Deep Mantle written by Robert D. van der Hilst and published by American Geophysical Union. This book was released on 2005-01-14 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 160. Understanding the inner workings of our planet and its relationship to processes closer to the surface remains a frontier in the geosciences. Manmade probes barely reach ˜10 km depth and volcanism rarely brings up samples from deeper than ˜150 km. These distances are dwarfed by Earth's dimensions, and our knowledge of the deeper realms is pieced together from a range of surface observables, meteorite and solar atmosphere analyses, experimental and theoretical mineral physics and rock mechanics, and computer simulations. A major unresolved issue concerns the nature of mantle convection, the slow (1-5 cm/year) solid-state stirring that helps cool the planet by transporting radiogenic and primordial heat from Earth's interior to its surface. Expanding our knowledge here requires input from a range of geoscience disciplines, including seismology, geodynamics, mineral physics, and mantle petrology and chemistry. At the same time, with better data sets and faster computers, seismologists are producing more detailed models of 3-D variations in the propagation speed of different types of seismic waves; new instrumentation and access to state-of-the-art community facilities such as synchrotrons have enabled mineral physicists to measure rock and mineral properties at ever larger pressures and temperatures; new generations of mass spectrometers are allowing geo-chemists to quantify minute concentrations of diagnostic isotopes; and with supercomputers geodynamicists are making increasingly realistic simulations of dynamic processes at conditions not attainable in analogue experiments. But many questions persist. What causes the lateral variations in seismic wavespeed that we can image with mounting accuracy? How reliable are extrapolations of laboratory measurements on simple materials over many orders of magnitude of pressure and temperature? What are the effects of volatiles and minor elements on rock and mineral properties under extreme physical conditions? Can ab initio calculations help us understand material behavior in conditions that are still out of reach of laboratory measurement? What was the early evolution of our planet and to what extent does it still influence present-day dynamics? And how well do we know such first-order issues as the average bulk composition of Earth?
Download or read book California Basins written by United States. National Resources Committee. Water Resources Committee and published by . This book was released on 1937 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The History of the Study of Landforms or the Development of Geomorphology Volume 5 written by T.P. Burt and published by Geological Society of London Memoirs. This book was released on 2022-10-20 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: Co-published with British Society for Geomorphology This volume is the fifth in the definitive series, The History of the Study of Landforms or the Development of Geomorphology. Volume 1 (1964) dealt with contributions to the field up to 1890, Volume 2 (1973) with the concepts and contributions of William Morris Davis and Volume 3 (1991) covered historical and regional themes during the ‘classic’ period of geomorphology (1890–1950). Volume 4 (2008) concentrated on studies of geomorphological processes and Quaternary geomorphology between 1890 and 1965; by the end of this period, process-based studies had become dominant. Volume 5 builds on this platform, covering in detail the revolutionary changes in approach that characterized the study of geomorphology in the second half of the twentieth century. It is divided into three sections: the first deals with changes in approach and method; the second with changes in ideas and the broader scientific context within which geomorphology is studied; and the final section details advances in research on processes and landforms. The volume’s objective is to describe and analyse many of the developments that provide a foundation for the rich and varied subject matter of twenty-first century geomorphology.
