Download or read book Discrimination of Earthquakes and Chemical Explosions with a Regional Network written by Peder Johansson and published by . This book was released on 1987 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book REGIONAL SEISMIC CHEMICAL AND NUCLEAR EXPLOSION DISCRIMINATION written by V. Johnson and published by . This book was released on 2006 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: We continue exploring methodologies to improve regional explosion discrimination using the western U.S. as a natural laboratory. 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 explosion 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. Even after correcting for average path and site effects, regional phase ratios contain a large amount of scatter. This scatter appears to be due to variations in source properties such as depth, focal mechanism, stress drop, in the near source material properties (including emplacement conditions in the case of explosions) and in variations from the average path and site correction. Here we look at several kinds of averaging as a means to try and reduce variance in earthquake and explosion populations and better understand the factors going into a minimum variance level as a function of epicenter (see Anderson ee et al. this volume). We focus on the performance of P/S ratios over the frequency range from 1 to 16 Hz finding some improvements in discrimination as frequency increases. We also explore averaging and optimally combining P/S ratios in multiple frequency bands as a means to reduce variance. Similarly we explore the effects of azimuthally averaging both regional amplitudes and amplitude ratios over multiple stations to reduce variance. Finally we look at optimal performance as a function of magnitude and path length, as these put limits the availability of good high frequency discrimination measures.

Download or read book Investigations Into Seismic Discrimination Between Earthquakes Chemical Explosions and Nuclear Explosions written by and published by . This book was released on 1995 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report we describe some results of investigations on a problem of discrimination between nuclear explosions, chemical explosions and earthquakes, carried out in the Complex Seismological Expedition of the Joint Institute of Physics of the Earth of the Russian Academy of Sciences. Records of underground nuclear explosions from the Semipalatinsk test site, and from region the Pre-Caspian depression, and also records of nearby chemical explosions and earthquakes were processed. We analysed records of permanent and temporary stations, located mainly in the North Tien Shan, northern Kazakhstan and Urals regions. We studied the influence of regional conditions on the effectiveness of seismic monitoring of nuclear explosions. Various amplitude criteria of the discrimination between explosions and earthquakes are considered. We analyzed possibilities to discriminate different source types using spectral-temporal characteristics of seismograms. The nature of some wave types, recorded at region distances, is investigated. We consider possibilities of discrimination between nuclear and chemical explosions and earthquakes using analysis of characteristics of irregular waves. We outline future investigations, connected with the study of the unique set of seismograms kept in the CSE.

Download or read book Discrimination Between Earthquakes and Chemical Explosions in Eastern Russia Using Amplitude Ratios Obtained from Analog Records written by Lepolt Linkimer and published by . This book was released on 2006 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Regional Discrimination of Quarry Blasts Earthquakes and Underground Nuclear Explosions written by T. J. Bennett and published by . This book was released on 1989 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigations conducted under this contract focused on analyses of the higher-frequency phases observed at regional distances from underground nuclear explosions, earthquakes, and commercial blasts. These analyses systematically compared the time-domain amplitude and spectral characteristics of the observed regional seismic signals in order to identify diagnostic differences which would be indicative of source type. The sources were located in three tectonic environments: (1) eastern North America, (2) southern Soviet Union, and (3) western United States. Each source environment provides a unique contribution to the regional discrimination problem. For these source regions digital data from several different high-quality seismic networks were analyzed. The data sources were the Regional Seismic Test Network (RSTN), the Eastern Canada Telemetered Network (ECTN), the Chinese Digital Seismic Network (CDSN), the Soviet/Natural Resources Defense Council (NRDC) network, and the Lawrence Livermore National Laboratory (LLNL) network. (jhd).

Download or read book Monitoring the Comprehensive Nuclear Test Ban Treaty Seismic Event Discrimination and Identification written by William R. Walter and published by Springer. This book was released on 2013-04-18 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: In September 1996, the United Nations General Assembly adopted the Comprehensive Nuclear-Test-Ban Treaty (CTBT), prohibiting nuclear explosions worldwide, in all environments. The treaty calls for a global verification system, including a network of 321 monitoring stations distributed around the globe, a data communications network, an international data center, and onsite inspections, to verify compliance. The problem of identifying small-magnitude banned nuclear tests and discriminating between such tests and the background of earthquakes and mining-related seismic events, is a challenging research problem. Because they emphasize CTBT verification research, the 12 papers in this special volume primarily addresses regional data recorded by a variety of arrays, broadband stations, and temporarily deployed stations. Nuclear explosions, earthquakes, mining-related explosions, mine collapses, single-charge and ripple-fired chemical explosions from Europe, Asia, North Africa, and North America are all studied. While the primary emphasis is on short-period, body-wave discriminants and associated source and path corrections, research that focuses on long-period data recorded at regional and teleseismic distances is also presented Hence, these papers demonstrate how event identification research in support of CTBT monitoring has expanded in recent years to include a wide variety of event types, data types, geographic regions and statistical techniques.

Download or read book Discrimination Between Eathquakes and Chemical Explosions Using Artificial Neural Networks written by Ajit Kundu and published by . This book was released on 2012 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigations Into Seismic Discrimination Between Earthquakes Chemical Explosions and Nuclear Explosions written by L. V. Antonova and published by . This book was released on 1995 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: We analyzed possibilities to discriminate different source types using spectral-temporal characteristics of seismograms. The nature of some wave types, recorded at regional distances, is investigated. We consider possibilities of discrimination between nuclear and chemical explosions and earthquakes using analysis of characteristics of irregular waves. We outline future investigations, connected with the study of the unique set of seismograms kept in the CSE.

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.

Download or read book Earthquake Or Explosion written by Lepolt Linkimer and published by . This book was released on 2007 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discrimination between earthquakes and chemical explosions is a significant problem facing many regional seismic networks around the world. Both earthquakes and chemical explosions are sources of elastic waves; therefore, both are recorded by seismic networks. In this study various types of Pg/Sg amplitude phase ratios are explored as discriminants to distinguish between earthquakes and explosions. Amplitude information from 237 earthquakes (1.5

Download or read book Chemical Explosions and the Discrimination Problem written by and published by . This book was released on 1991 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report is in three sections: Section one describes empirical estimates of yield and tectonic release for 71 underground nuclear explosions conducted at the Shagan River Test Site, Kazakhstan, from 1977 to 1989. The method is based upon teleseismic observations of fundamental mode Love and Rayleigh waves at stations of the GDSN, CDSN, RSTN, and IRIS/USGS GSN. In 1977 as few as five stations were providing data, while in the late 1980's more than 25 stations were operational. Section two makes a case for generating lists of problems events - seismic sources whose signals cannot easily be discriminated - as a mechanism for achieving three goals: (1) encouraging seismologists to contribute data that may help to discriminate events listed; (2) training; and (3) helping to build consensus in the technical community, on what types of problem events are truly intractable with current data Section three describes spectral-temporal characteristics of regional seismograms and shows how they can be used to discriminate between different types of seismic sources. We analyze the high-frequency (1-40 hz) spectral of chemical explosions and earthquakes at local and regional distances to understand the seismic signal characteristics of different types of sources and to find stable discriminators. We evaluate the application of the spectrogram technique to regional seismograms in different geologic settings using data from single explosions, multiple-hole instantaneous explosions, ripple-fired quarry blasts, and earthquakes. The effects on high frequency spectra of local source and recorder site conditions and source to receiver path are also analyzed.

Download or read book Forensic Explosion Seismology written by So Gu Kim and published by Cambridge Scholars Publishing. This book was released on 2020-03-02 with total page 531 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses three major physical phenomena for active source seismology, namely underwater explosions, underground nuclear explosions, and large-scale on-surface chemical explosions. In particular, contributors consider how to use the technologies and applications in active source seismology and seismo-acoustics, rather than the theoretical approach for the resolution of the forensic explosion seismology in the light of an application for defense sciences. The volume also presents seismological investigations of discrimination between earthquakes and man-made explosions.

Download or read book EMPIRICAL OBSERVATIONS OF EARTHQUAKE EXPLOSION DISCRIMINATION USING P written by and published by . This book was released on 2007 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: We continue exploring methodologies to improve earthquake-explosion discrimination using regional amplitude ratios such as P/S. The earliest simple source models predicted P/S wave amplitudes for explosions should be much larger than for earthquakes across the body wave spectrum. However empirical observations show the separation of explosions from earthquakes using regional P/S amplitudes is strongly frequency dependent, with relatively poor separation at low frequencies (≈ 1 Hz) and relatively good separation at high frequencies (> ≈3 Hz). We demonstrate this using closely located pairs of earthquakes and explosions recorded on common, publicly available stations at test sites around the world e.g. Nevada, Lop Nor, Novaya Zemlya, Semipalatinsk, India, Pakistan, and North Korea. We show this pattern appears to have little dependence on the point source variability revealed by longer period surface wave modeling. For example regional waveform modeling shows strong tectonic release from the May 1998 India test in contrast with very little tectonic release in the recent North Korea test, but the P/S discrimination behavior is similar in both events, using the limited regional data available. While accepted explosion P-wave models have been available for many years, the frequency behavior of the P/S discriminant has inspired a variety of competing models to explain how explosions generate S-waves. We briefly review some of these models in the context of the P/S discriminant observations. One hypothesis is that S-waves are generated mainly from conversion of P-waves and surface waves, so S-waves from explosions can be predicted from the P-wave models via a frequency dependent transfer function. A different hypothesis is that significant generation of S-waves comes from the CLVD (compensated linear vector dipole) component created by spall above the explosion. A recent model by Fisk (2006) shows the explosion S-wave spectra can be modeled using the P-wave spectra with the corner frequency reduced by the ratio of the wave velocities, which seems to imply a direct generation of S-waves in the source region. We examine a number of nuclear tests from around the world in light of these models. Given the importance of depth on some of the model predictions we reexamine some of the overburied explosions in Nevada. We also look at chemical explosions, including dedicated single shots at different depths and mining shots at adjacent open pit and underground mines to look at depth effects. Finally we examine a subset of Nevada data with signal above noise up to 16 Hz to determine if discrimination performance saturates at frequencies around 6 Hz as some models predict, or continues to improve at higher frequencies.

Download or read book Discrimination of Earthquakes and Explosions at Regional Distances Using Complexity written by and published by . This book was released on 1993 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Regional Discrimination Research and Methodology Implementation Analyses of CDSN and Soviet IRIS Data written by and published by . This book was released on 1990 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research is to evaluate the capability of regional stations in discrimination of underground nuclear explosions from earthquakes and non-nuclear explosions. Efforts during the first year of this program have focused on studies of regional data from the Chinese Digital Seismic Network(CDSN) and Incorporated Research Institutions for Seismology(IRIS) stations in the Soviet Union. A previous report described observations from the CDSN station at WMQ which indicated differences in relative spectral content of Lg versus regional P for explosions and earthquakes. In the current research we used different spectral analyses to study the signals from a larger event sample including 27 East Kazakh explosions and 32 regional earthquakes. Lg/P ratios for regional earthquakes were found to be enriched at high frequencies compared to similar explosions. In comparing explosions from Shagan River and Degelen Mountain areas it was found that regional P signals are relatively stronger from SR than from DM explosions with similar Lg signals. Analysis of East Kazakh explosion signals recorded at Soviet IRIS stations indicates that regional signals are observable down to very low magnitudes. Lg magnitude residuals from these stations have been used to derive effective Q values for these paths.

Download or read book Estimating Characteristics of Chemical Explosions in New England and Eastern Kazakhstan Using Local and Regional Seismic Data written by A. L. Kafka and published by . This book was released on 1989 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the problems associated with monitoring a comprehensive nuclear test ban treaty is that of discrimination between small explosions and earthquakes based on seismic data. Chemical explosions are used routinely in the mining and construction industries in both the United States and the Soviet Union. These chemical explosions usually occur at very shallow depths (a few tens of feet), and probably are all shallower than a few hundred meters. Most nuclear explosions are detonated at depths of less than about one kilometer, and the deepest underground nuclear explosions are a few kilimeters deep. On the other hand, most earthquakes occur deeper in the earth's crust. Thus, accurate estimation of the depths of seismic sources can be helpful in discriminating earthquakes from explosions. During the past several years, the Principal Investigator (PI) for this summer project has been studying the use of short-period Rayleigh waves (Rg) as a depth discriminant for seismic sources in New England.

Download or read book RMS Lg Studies of Underground Nuclear Explosions in the U S S R and the U S written by P. G. Richards and published by . This book was released on 1993 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: