Download or read book Fractal Approach to the Regional Seismic Event Discrimination Problem written by D. N. Belyashov and published by . This book was released on 2000 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the framework of the Comprehensive Test Ban Treaty, development of reliable methods to discriminate between underground nuclear explosions and earthquakes at regional distances (less than 2500km) continues to be very important especially in connection with the last (in May, 1998) nuclear explosions conducted at Indian and Pakistan test sites. Since the lithosphere is a fractal, we suppose the signals, which propagate through the media, inherit its self similar' (scaling) features. We assumed that these features of explosions and earthquakes or their topological reconstructions (embeddings) have to be different. Scaling reflects correlations of more high order then it is possible to estimate by linear discriminating methods and can be used as base of non-linear discrimination. We propose to build a universal geometrical model of a seismic signal using the canon algorithm of F. Takens and to estimate scaling of the model. The scaling features were used as patterns of seismic signals for entering them into an artificial neural network. Records of nuclear explosions and earthquakes from different regions were included into the training set. The net was trained to classify types of seismic events. Results have shown 80% correct classification of the unknown signals. As additional tools for distinguishing between nuclear explosions and earthquakes we propose to use Hurst's method and the cross correlation method. Results of using these methods are demonstrated on examples of some explosions and earthquakes.

Download or read book Paradigms Of Complexity Fractals And Structures In The Sciences written by Miroslav M Novak and published by World Scientific. This book was released on 2000-04-18 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Every reader will find something of interest in this book — from superdiffusion of the ocean surface to fetal heartbeats, from solar wind to the wearing-out of tools, from radioactive contamination to texture analysis, from image rendering to neural developments. The all-pervading link connecting these disparate disciplines is the realization that a linear approach to the majority of natural processes is at best only an approximation that can frequently be downright misleading. Consequently, the rise of what is broadly called the theory of complexity has gained tremendous momentum in the last decade or two. This modern approach aims at, and frequently succeeds in, correctly explaining many natural processes.The papers in this volume are based on presentations of the sixth international conference exploring the above-mentioned issues. These conferences are now regular and well established among the nonlinear series of conferences. This conference series is organized in different geographical regions, to encourage international collaboration. Among the distinguishing features of the series is its multidisciplinary nature, which has been growing steadily.

Download or read book Application of Regularized Discrimination Analysis to Regional Seismic Event Identification written by and published by . This book was released on 2000 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a generalized multivariate seismic event identification method, Regularized Discrimination Analysis (RDA) [Friedman 1989], that can be applied to a large number of regional discriminants. RDA is readily adaptable to an outlier or classical identification approach to regional seismic identification. RDA is designed to address the problems associated with linear (LDA) and quadratic (QDA) discrimination in small-sample, high-dimensional settings. RDA includes LDA, QDA and Euclidean distance based nearest neighbor discrimination in its parameterization. RDA can be used to transition from an outlier analysis approach to seismic identification to classical discrimination as quality explosion calibration data are collected. Further, RDA provides the statistical structure to model highly correlated seismic measurements. We demonstrate the importance of including the correlation structure between seismic measurements in event identification. Not including this correlation structure in any identification framework can aggravate identification errors and give an erroneous impression of capability. With RDA, a large number of amplitudes from a Magnitude and Distance Amplitude Correction (MDAC) analysis [see Taylor et al. 1999] can be used and no a priori sub-selection of amplitudes (or discriminants) is necessary.

Download or read book Discrimination of Problem Seismic Events by Modeling the Combined Effects of Deterministic and Statistical Structure on Regional Seismograms written by and published by . This book was released on 2015 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Case Studies of Seismic Discrimination Problems and Regional Discriminant Transportability written by Douglas R. Baumgardt and published by . This book was released on 1995 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes case studies of regional seismic discriminants, using the Intelligent Seismic Event Identification System (ISEIS), and addresses issues related to the transportability of regional discriminants. Some of the key results of this study include: (1) Observations of large Lg waves from mine blasts. (2) Investigation of the P/S frequency-dependence discriminant. (3)The importance of signal decorrelation in the generation of spectral scalloping by ripple fired mine blasts. (4) Path corrections for the Lg spectral ratio discriminant using a simple anelastic attenuation model. Also described in this report is a discrimination study of the January 5, 1995 Urals mine event. Because there were no nearby earthquakes or blasts in the Urals mine region, recordings of the event at regional station ARU were compared with WMQ recordings of Chinese nuclear blasts and earthquakes at comparable distance, but in a different geographic and tectonic region. This comparison indicated that the January 3, 1995 event had Pn/Lg amplitude ratios more comparable to Chinese earthquakes than nuclear explosions. Based on the analysis of Pn/Lg ratios at NORESS and comparison those produced by PNEs in the same region recorded at NORSAR, we conclude that the January 3, 1995 event produced much stronger shear waves (Sn, Lg) relative to P than did nuclear blasts. We conclude that the event was probably a mine tremor or collapse.

Download or read book Fractal Analysis for Natural Hazards written by Giuseppe Cello and published by Geological Society of London. This book was released on 2006 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Earth Sciences, the concept of fractals and scale invariance is well-recognized in many natural objects. However, the use of fractals for spatial and temporal analyses of natural hazards has been less used (and accepted) in the Earth Sciences. This book brings together twelve contributions that emphasize the role of fractal analyses in natural hazard research, including landslides, wildfires, floods, catastrophic rock fractures and earthquakes. A wide variety of spatial and temporal fractal-related approaches and techniques are applied to 'natural' data, experimental data, and computer simulations. These approaches include probabilistic hazard analysis, cellular-automata models, spatial analyses, temporal variability, prediction, and self-organizing behaviour. The main aims of this volume are to present current research on fractal analyses as applied to natural hazards, and to stimulate the curiosity of advanced Earth Science students and researchers in the use of fractals analyses for the better understanding of natural hazards.

Download or read book Cross Region Analysis Path Corrections and the Transportability of Regional Seismic Discriminants written by Douglas R. Baumgardt and published by . This book was released on 1995 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study has investigated the problem of transporting regional discriminants, principally the regional P/S amplitude ratio and Lg spectral discriminants, between regions of differing tectonic type. The effects of differential regional phase attenuation and propagation blockages need to be taken into account and corrected before decision criteria for discriminants developed in one tectonic region can be transported to a different tectonic region. We have developed a set of frequency-dependent distance correction curves to correct the Pn/Sn and Pn/Lg amplitude ratio to a standard distance. Similar corrections have been developed for the Lg spectral ratio using a standard Lg attenuation model. Also, we have developed a method, called cross-region seismic event characterization, to characterize and identify new events which occur in aseismic regions or regions lacking known source types. Discrimination processing results of the Intelligent Seismic Event Identification System (ISEIS) for many different regions are stored in an Oracle database and can be called up on a regionalized basis. When a new event occurs, the method of cross-region seismic event characterization tries to find reference events from different regions, probably recorded at different stations than the new event, but at comparable distance for comparison which can be used as reference or training events to identify the new event. We construct crustal cross sections for the different propagation paths and determine if the new event has similar cross sections as the reference events. If the paths are not too different, the discriminants can be directly compared, after correcting for differences in distance.

Download or read book Seismic Signal Detection by Fractal Dimension Approach written by B. K. Gangrade and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Regional Seismic Discrimination in Central Asia with Emphasis on Western China written by and published by . This book was released on 1996 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: In support of an anticipated Comprehensive Test Ban Treaty, the authors have started to evaluate regional seismic event discrimination capabilities for central Asia, emphasizing western China. The authors have measured noise and seismic phase amplitudes of over 250 earthquakes and 18 underground nuclear explosions recorded at the broadband, digital station WMQ in western China and over 100 earthquakes and 5 nuclear explosions at station AAK in Kyrgyzstan. The explosions are from the Kazakh Test Site (KTS) and Lop Nor, China. The earthquakes are mostly from northwest China. They have also evaluated a single suspected chemical explosion. Event magnitudes (m{sub b}) range between 2.5 and 6.5 and maximum event-station distance is about 1,700 km. Using these measurements the authors formed phase, spectral, cross-spectral, short-period/long-period, and long-period ratios to test many possible event discriminants. All ratios were corrected for distance effects before forming ratio-versus-magnitude discrimination plots. The authors found that all five classes of these discriminants are useful for separating earthquakes from explosions in central Asia, provided the right combinations of frequency bands and phases are selected. Results are described.

Download or read book Regional Seismic Discrimination Research at LLNL written by and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to verify a Comprehensive Test Ban Treaty (CTBT) depends in part on the ability to seismically detect and discriminate between potential clandestine underground nuclear tests and other seismic sources, including earthquakes and mining activities. Regional techniques are necessary to push detection and discrimination levels down to small magnitudes, but existing methods of event discrimination are mainly empirical and show much variability from region to region. The goals of Lawrence Livermore National Laboratory's (LLNL's) regional discriminant research are to evaluate the most promising discriminants, improve the understanding of their physical basis and use this information to develop new and more effective discriminants that can be transported to new regions of high monitoring interest. In this report the authors discuss preliminary efforts to geophysically characterize the Middle East and North Africa. They show that the remarkable stability of coda allows one to develop physically based, stable single station magnitude scales in new regions. They then discuss progress to date on evaluating and improving physical understanding and ability to model regional discriminants, focusing on the comprehensive NTS dataset. The authors apply this modeling ability to develop improved discriminants including slopes of P to S ratios. They find combining disparate discriminant techniques is particularly effective in identifying consistent outliers such as shallow earthquakes and mine seismicity. Finally they discuss development and use of new coda and waveform modeling tools to investigate special events.

Download or read book Fractals and Chaos in the Earth Sciences written by SAMMIS and published by Birkhäuser. This book was released on 2013-11-22 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book LLNL s Regional Seismic Discrimination Research written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of the Department of Energy's research and development effort to improve the monitoring capability of the planned Comprehensive Nuclear-Test-Ban Treaty international monitoring system, Lawrence Livermore Laboratory (LLNL) is testing and calibrating regional seismic discrimination algorithms in the Middle East, North Africa and Western Former Soviet Union. The calibration process consists of a number of steps: (1) populating the database with independently identified regional events; (2) developing regional boundaries and pre-identifying severe regional phase blockage zones; (3) measuring and calibrating coda based magnitude scales; (4a) measuring regional amplitudes and making magnitude and distance amplitude corrections (MDAC); (4b) applying the DOE modified kriging methodology to MDAC results using the regionalized background model; (5) determining the thresholds of detectability of regional phases as a function of phase type and frequency; (6) evaluating regional phase discriminant performance both singly and in combination; (7) combining steps 1-6 to create a calibrated discrimination surface for each stations; (8) assessing progress and iterating. We have now developed this calibration procedure to the point where it is fairly straightforward to apply earthquake-explosion discrimination in regions with ample empirical data. Several of the steps outlined above are discussed in greater detail in other DOE papers in this volume or in recent publications. Here we emphasize the results of the above process: station correction surfaces and their improvement to discrimination results compared with simpler calibration methods. Some of the outstanding discrimination research issues involve cases in which there is little or no empirical data. For example in many cases there is no regional nuclear explosion data at IMS stations or nearby surrogates. We have taken two approaches to this problem, first finding and using mining explosion data when available, and second using test-site based models to transport earthquake-explosion discrimination behavior to new regions. Finally an important component of our research is assessing improvement in the ability to discriminate events. By combining the multivariate discriminants with the threshold detection curves for the regional seismic phases used in those discriminants, we have started to make maps of the probability an event will be identified properly. These maps serve a broad range of purposes from demonstrating progress to funding agencies to prioritizing research and calibration efforts.

Download or read book A Discrimination Analysis of Regional Seismic Data Recorded at Tonto Forest Observatory from Nevada Test Site Explosions and Nearby Earthquakes written by J. R. Murphy and published by . This book was released on 1981 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: The principal objectives of the research reported here are to identify any diagnostic differences between regional seismic phases produced by earthquakes and underground nuclear explosions and to assess their applicability to events occurring in various regions of the U.S.S.R. Two approaches are used: one employs traditional time-domain amplitude and period measurements to compare the relative excitation of various regional phases for earthquakes and explosions, while the second focuses on more sophisticated measurement or processing techniques such as spectral ratios or narrow-band filtering to extract information about frequency differences in the signals generated by the two types of events. The research reported here was directed at identification of discriminants based on measurements of seismic phases at regional distances from a well-controlled set of Western U.S. explosions and nearby earthquakes. The set includes more than 50 Nevada Test Site events (explosions and nearby earthquakes) recorded at the Tonto Forest Observatory in Arizona. The investigation included spectral analyses of the short-period regional phases, Pn, Pg, and Lg which follows-up a previously reported study of time-domain characteristics of these phases. In addition, the current study includes an analysis of the time-domain characteristics of the long-period data from the Nevada Test Site event set, with particular emphasis on the potential applicability of the Ms/mb discriminant to the identification of small events (mb

Download or read book Discrimination Calibration Analysis Methods for Regional Stations written by and published by . This book was released on 2008 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: For event discrimination, operational implementation of a regional seismic station requires three sequential calibration analyses. (1) Magnitude, distance, and amplitude corrections (MDAC) made to observe regional amplitudes are necessary so that what remains in the corrected amplitude is mostly information about the seismic source-type. Corrected amplitudes can be used in ratios to discriminate between earthquakes and explosions. Calibration of MDAC can be accomplished with empirical Bayes estimation, which naturally provides metrics to determine when adequate calibration data have been acquired, and provides statistical assurance that the errors associated with MDAC calibration are negligible in future operational discrimination analysis. (2) MDAC-corrected amplitudes can then be used in ratios to discriminate between earthquakes and explosions. However, there remain source effects such as those due to depth, focal mechanism, local material property and apparent stress variability that cannot easily be determined and applied as amplitude corrections. We have developed a mathematical model to capture these near source effects as random (unknown) giving an error partition of three sources: model inadequacy, station noise and amplitude correlation. This mathematical model is the basis for a general multi-station regional discriminant. Calibration analysis for the standard error of the discriminant includes the calculation of the variances of model inadequacy and station noise, and amplitude correlation. (3) Likelihood-based seismic event identification analysis with MDAC discriminants requires estimated source population means and covariance matrices for the discriminants from each of the possible source types used in our analysis (e.g., deep earthquake, shallow earthquake, and explosion).

Download or read book Fractal and Chaotic Properties of Earthquakes written by Christian Goltz and published by Springer. This book was released on 1997 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the application of fractal and nonlinear time-series analysis to seismicity and earthquakes within the framework of earthquake prediction research. Emphasis is on theoretical foundations as well as practical implementation and pitfalls to enable readers to conduct their own analyses. The theoretical parts include introductions to fractals and multifractals, the relation between fractal dimension and entropy, the Hurst phenomenon, basic ideas of low-dimensional chaotic dynamics and a roadmap of nonlinear time-series analysis. Practical implementation is discussed in each case and synthetic data sets are analyzed. Fractal methods are applied to landslide and seismicity patterns in space and time, nonlinear analysis is carried out for radon and strain data as well as earthquake intervals. Due to the comprehensive coverage of theoretical background and step-by-step applications, readers of all levels will benefit from this book.

Download or read book Evaluation of Regional Seismic Discriminants Using the Intelligent Seismic Event Identification System written by and published by . This book was released on 1992 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the effectiveness of several regional waveform discriminants and processing methods are being evaluated using a large database of regional waveforms. ISEIS has been installed at the Center for Seismic Studies (CSS) where it is being used to process and analyze discriminants for seismic events formed by the Intelligent Monitoring System (IMS). The system has undergone a number of modifications to interface with the CSS databases and to improve the processing efficiency of the system in the CSS environment. Also, a number of new features have been added to facilitate the processing of the data and discrimination research, including automated feature extraction and processing, improved plotting displays for reviewing IMS and analyst phase identification, data viewing displays for reference events plotted in scatterplots, a new top-level display for viewing ISEIS processing results, multichannel coherence and deconvolution processing interfaces, and a research interface for multivariate classification using a simulated neural network approach.

Download or read book Regional Seismic Discrimination Optimization With and Without Nuclear Test Data written by W. R. Walter and published by . This book was released on 2005 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The western U.S. has abundant natural seismicity, historic nuclear explosion data, and widespread mine blasts, making it a good testing ground to study the performance of regional source-type discrimination techniques. We have assembled and measured a large set of these events to systematically explore how to best optimize discrimination performance. Nuclear explosions can be discriminated from a background of earthquakes using regional phase (Pn, Pg, Sn, Lg) amplitude measures such as high frequency P/S ratios. The discrimination performance is improved if the amplitudes can be corrected for source size and path length effects. We show good results are achieved using earthquakes alone to calibrate for these effects with the MDAC technique (Walter and Taylor, 2001). We show significant further improvement is then possible by combining multiple MDAC amplitude ratios using an optimized weighting technique such as Linear Discriminant Analysis (LDA). However this requires data or models for both earthquakes and explosions. In many areas of the world regional distance nuclear explosion data is lacking, but mine blast data is available. Mine explosions are often designed to fracture and/or move rock, giving them different frequency and amplitude behavior than contained chemical shots, which seismically look like nuclear tests. Here we explore discrimination performance differences between explosion types, the possible disparity in the optimization parameters that would be chosen if only chemical explosions were available and the corresponding effect of that disparity on nuclear explosion discrimination. There are a variety of additional techniques in the literature also having the potential to improve regional high frequency P/S discrimination. We explore two of these here: three-component averaging and maximum phase amplitude measures. Typical discrimination studies use only the vertical component measures and for some historic regional nuclear records these are all that are available. However S-waves are often better recorded on the horizontal components and some studies have shown that using a three-component average or a vertical-P/horizontal-S or other three-component measure can improve discrimination over using the vertical alone (e.g. Kim et al. 1997; Bowers et al 2001). Here we compare the performance of vertical and three-component measures on the western U.S. test set. A complication in regional discrimination is the variation in P and S-wave propagation with region. The dominantly observed regional high frequency S-wave can vary with path between Sn and Lg in a spatially complex way. Since the relative lack of high frequency S-waves is the signature of an explosion, failing to account for this could lead to misidentifying an earthquake as an explosion. The regional P phases Pn and Pg vary similarly with path and also with distance, with Pg sometimes being a strong phase at near regional distances but not far regional. One way to try and handle these issues is to correct for all four regional phases but choose the phase with the maximum amplitude. A variation on this strategy is to always use Pn but choose the maximum S phase (e.g. Bottone et al. 2002). Here we compare the discrimination performance of several different (max P)/(max S) measures to vertical, three-component and multivariate measures. Our preliminary results show that multivariate measures perform much better than single ratios, though transportability of the LDA weights between regions is an issue. Also in our preliminary results, we do not find large discrimination performance improvements with three-component averages and maximum phase amplitude measures compared to using the vertical component alone.