21 Matching Results

Search Results

Advanced search parameters have been applied.

Status report on method and results for new discriminants and combinations of discriminants for different ranges

Description: A number of discriminants have been developed for seismic monitoring. These include the Ms-mb discriminant which measures differences in surface and body wave magnitudes (e.g., Marshall and Basham, 1972), short period P to S wave amplitude ratio discriminants (e.g., Blandford, 1981) and spectral ratios discriminants (e.g., Murphy and Bennett, 1982). Unfortunately, existing discrimination capabilities are insufficient to meet the needs that will be required by a comprehensive test ban treaty (CTBT). Of particular concern are limitations of current capabilities for discriminating small magnitude (mb<4) seismic events such as earthquakes, mining explosions, and mining related seismicity (rockbursts and collapse events) from small magnitude nuclear explosions (both coupled and decoupled). In this report, we summarize our work on the development of new methods for discriminating such small magnitude events.
Date: April 7, 1995
Creator: Goldstein, P.
Partner: UNT Libraries Government Documents Department

SAC Availability for the IRIS Community

Description: SAC (also known as SAC2000) is a signal processing and analysis code that has been developed by Lawrence Livermore National Laboratory (LLNL) over the past 20+ years for a variety of seismic and geophysical research projects. SAC has evolved into a general purpose interactive program designed for the study of sequential signals, especially time-series data. Emphasis has been placed on analysis tools used by research seismologists in the detailed study of seismic events. Analysis capabilities include general arithmetic operations, Fourier transforms, three spectral estimation techniques, IIR and FIR filtering, signal stacking, decimation, interpolation, correlation, and seismic phase picking. SAC also contains an extensive graphics capability. SAC is used extensively by the seismic community because: (1) it has a broad range of well-tested, efficient data analysis capabilities (examples include: data inspection, phase picking, signal correction, quality control, unary and binary data operations, travel-time analysis, spectral analysis including high-resolution spectral estimation, spectrograms and binary sonograms, and array and three-component analysis), (2) it is easy to use and reliable, (3) it has a macro programming language that allows users to develop innovative new analysis techniques, (4) it has interfaces to the Unix operating system, Matlab (www.mathworks.com), and the Generic Mapping Tools (GMT) software (Wessel and Smith, 1991, 1998 and gmt.soest.hawaii.edu) that make it very flexible, allowing researchers to solve many research problems innovatively with minimal programming effort, and (5) the suite of analysis capabilities are integrated so that innovative processing schemes are easily implemented. SAC is also widely used because of its user oriented development philosophy, which has led to consistent, easy to use capabilities that are backward compatible. A sample of some of SAC's capabilities is displayed in Figure 1.
Date: April 6, 2005
Creator: Goldstein, P & Snoke, A
Partner: UNT Libraries Government Documents Department

Influence of deep sedimentary basins, crustal thining, attenuation, and topography on regional phases: selected examples from theEastern Mediteranean and the Caspian Sea Regions

Description: Monitoring of a CTBT will require transportable seismic identification techniques, especially in regions where there is limited data. Unfortunately, most existing techniques are empirical and can not be used reliably in new regions. Our goal is to help develop transportable regional identification techniques by improving our ability to predict the behavior of regional phases and discriminants in diverse geologic regions and in regions with little or no data. Our approach is to use numerical modeling to understand the physical basis for regional wave propagation phenomena and to use this understanding to help explain observed behavior of regional phases and discriminants. In this paper, we focus on results from simulations of data in selected regions and investigate the sensitivity of these regional simulations to various features of the crustal structure. Our initial models use teleseismically estimated source locations, mechanisms, and durations and seismological structures that have been determined by others. We model the Mb 5.9, October 1992, Cairo Egypt earthquake at a station at Ankara Turkey (ANTO) using a two-dimensional crustal model consisting of a water layer over a deep sedimentary basin with a thinning crust beneath the basin. Despite the complex tectonics of the Eastern Mediterranean region, we find surprisingly good agreement between the observed data and synthetics based on this relatively smooth two-dimensional model.
Date: July 15, 1997
Creator: Goldstein, P.; Schultz, C. & Larsen, S.
Partner: UNT Libraries Government Documents Department

Recent developments in SAC2000

Description: Before discussing recent developments in SAC2000, I will summarize what SAC2000 is/does. SAC2000 is the rebirth and evolution of Lawrence Livermore National Laboratory`s (LLNL`s) Seismic Analysis Code (SAC) developed during the 1980`s for a variety of geophysical applications. Primary funding for the development of SAC2000 has been through the LLNL as part of the Department of Energy`s (DOE`s) CTBT R&D program. The primary development goals for SAC2000 have been to meet the seismic signal processing and analysis needs of the DOE CTBT R&D teams and the rest of the CTBT R&D community. SAC2000`s strengths include its ability to process a diverse range of data types, its extensive, well documented signal processing capabilities (both on-line and on the web at http://www-ep.es.llnl.gov/tvp/sac.html), its macro language, and its ability to do both branch and interactive processing. Its extensive usage (over 200 institutions worldwide) had also made it much easier for researchers to develop collaborative research projects. SAC2000`s extensive signal processing capabilities include: data inspection, signal correction, and quality control, unary and binary data operations, travel-time analysis, spectral analysis including high-resolution spectral estimation, spectrograms and binary sonograms, and array and three-component analysis. Recent development in SAC2000 include: enhanced compatibility with the CSS3.0 database schema, complete compatibility with the widely used SEED data format instrument responses, map making capabilities via an interface to GMT, a new three component polarization and phase identification tool, an external interface that allows users to define their own commands, and an interface to MATLAB that allows the user to use MATLAB commands and scripts on SAC data from within SAC2000. We have also implemented a number of commands to enhance user efficiency and numerous improvements and enhancements to many individual SAC commands. Current development in SAC2000 are motivated by the need for easy and efficient access to, and processing and ...
Date: July 1, 1997
Creator: Goldstein, P.; Dodge, D. & Firpo, M
Partner: UNT Libraries Government Documents Department

A status report on the development of SAC2000: A new seismic analysis code

Description: We are developing a new Seismic Analysis Code (SAC2000) that will meet the research needs of the seismic research and treaty monitoring communities. Our first step in this development was to rewrite the original Seismic Analysis Code (SAC) -- a Fortran code that was approximately 140,000 lines long -- in the C programming language. This rewrite has resulted in a much more robust code that is faster, more efficient, and more portable than the original. We have implemented important processing capabilities such as convolution and binary monograms, and we have significantly enhanced several previously existing capabilities. For example, the spectrogram command now produces a correctly registered plot of the input time series and a color image of the output spectrogram. We have also added an image plotting capability with access to 17 predefined color tables or custom color tables. A rewritten version of the readcss command can now be used to access any of the documented css.3.0 database data formats, a capability that is particularly important to the Air Force Technical Applications Center (AFTAC) and the monitoring community. A much less visible, but extremely important contribution is the correction of numerous inconsistencies and errors that have evolved because of piecemeal development and limited maintenance since SAC was first written. We have also incorporated on-line documentation and have made SAC documentation available on the Internet via the world-wide-web at http://www-ep/tvp/sac.html.
Date: August 1, 1995
Creator: Goldstein, P. & Minner, L.
Partner: UNT Libraries Government Documents Department

Status report on preliminary assessment of variations of regional phases and discriminants with distance

Description: An improved understanding of the variability of regional seismic phases with distance is needed to improve the performance and transportability of regional seismic discriminants. Observations of large variations in regional phase amplitudes, over relatively short distances, are not uncommon. For example, large variations in Pn amplitudes of the Non-Proliferation Experiment (NPE) were observed along lines to the west (e.g., Keller et al., 1994), and northwest (e.g., McCormack et al., 1994). Numerous studies, in a number of areas, have also observed large variations in Sn and Lg over relatively short distances (e.g., Kadinsky-Cade et al., 1981; Ni and Barazangi, 1983). An improved understanding of these variations has been gained from numerous empirical observations (e.g., Chavez and Priestley, 1984; Zhang et al., 1994) and theoretical studies (e.g., Campillo, 1990, Kennett, 1993). We are developing a number of techniques and procedures for characterizing such features on a region specific basis.
Date: June 5, 1995
Creator: Goldstein, P. & Schultz, C.
Partner: UNT Libraries Government Documents Department

Simulation of Hypervelocity Penetration in Limestone

Description: A parameter study was performed to examine the (shock) damage obtained with long-rod and spherical mono-material penetrators impacting two varieties of limestone. In all cases, the impacts were assumed to be normal to the plane of the rock and at zero angle of attack (in the case of the rods). Impact velocities ranged to 15 km/s but most calculations were performed at 4 and 6 km/s and the penetrator mass was fixed at 1000 kg. For unlined underground structures, incipient damage was defined to occur when the peak stress, {sigma}{sub pk}, exceeds 1 kb (100 MPa) and the applied impulse per unit area, I{sub pk}, exceeds 1 ktap (1 kb-{micro}s). Severe damage was assumed to occur when {sigma}{sub pk} exceeds 1 kb and I{sub pk} exceeds 1000 ktaps. Using the latter definition it was found that severe damage in hard, non-porous limestone with spherical impactors extended to a depth of 9 m on-axis for an impact velocity of 4 km/s and 12 m at 6 km/s. Cylinders with length-to-diameter (L/D) ratio of 8.75 achieved depth to severe damage of 23 m and 40 m, respectively under the same conditions. For a limestone medium with 2% initial gas porosity, the latter numbers were reduced to 12 m and 18 m.
Date: May 31, 2005
Creator: Antoun, T; Glenn, L; Walton, O; Goldstein, P; Lomov, I & Liu, B
Partner: UNT Libraries Government Documents Department

LLNL`s regional seismic discrimination research

Description: The ability to negotiate and 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 our 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 we discuss our preliminary efforts to geophysically characterize two regions, the Korean Peninsula and the Middle East-North Africa. We show that the remarkable stability of coda allows us to develop physically based, stable single station magnitude scales in new regions. We then discuss our progress to date on evaluating and improving our physical understanding and ability to model regional discriminants, focusing on the comprehensive NTS dataset. We apply this modeling ability to develop improved discriminants including slopes of P to S ratios. We find combining disparate discriminant techniques is particularly effective in identifying consistent outliers such as shallow earthquakes and mine seismicity. Finally we discuss our development and use of new coda and waveform modeling tools to investigate special events.
Date: July 1, 1995
Creator: Walter, W.R.; Mayeda, K.M. & Goldstein, P.
Partner: UNT Libraries Government Documents Department

Status report of propagation models: Middle East and North Africa (S5.3)

Description: An improved understanding of the influence that tectonic structure has on regional seismic phases is needed to improve the current performance of regional discriminants and their transportability to the Middle East and North Africa. In the case that the crustal structure can be approximated by a flat layered laterally invariant medium, layer-cake reflectivity modeling can be used to obtain an accurate representation of regional phases. However, a laterally heterogeneous crust is just as common as a layered cake structure and in this case large variations in regional phase amplitudes are not uncommon. For instance, it has been shown that rough surface topography and undulations in the Moho can cause the transfer of energy between various surface wave modes and between surface waves and body waves greatly increasing the potential variability of seismic phases. Larger scale structure such as thickening or thinning of the crust can also greatly affect phase propagation. In some instances, changes between different tectonic regions such as that which occurs at a continental-oceanic boundary can completely block phases such as Lg rendering certain discriminants useless. In addition to structure along the path, lateral structure and free surface topography near the source and receiver can cause complex scattering effects with strong directional, frequency, and near-field effects. Given that the Middle East and North Africa cross many different tectonic boundaries, the authors are using numerical propagation models to understand how the relevant tectonic features affect the propagation of primary discriminant phases.
Date: November 1, 1995
Creator: Schultz, C.A.; Patton, H.J. & Goldstein, P.
Partner: UNT Libraries Government Documents Department

Implications of mining practices in an open-pit gold mine for monitoring of a comprehensive test-ban treaty

Description: This report summarizes the results of an experiment at the Gold Quarry pit, operated by the Newmont Gold Company at Carlin, NV The purpose of the experiment was to obtain local and regional seismic data, together with ``ground truth``, from conventional surface blasting activity and to use these data to help determine the effectiveness with which conventional mining blasts can be discriminated from underground nuclear explosions.
Date: January 1, 1996
Creator: Jarpe, S.P.; Moran, B.; Goldstein, P. & Glenn, L.A.
Partner: UNT Libraries Government Documents Department

Wave propagation modeling capabilities at LLNL: Applications to regional discrimination

Description: A primary goal of our research at LLNL has been to develop an assemblage of the most promising numerical techniques for simulating regional wave propagation through complex media. These numerical capabilities will be an integral part of our approach to regional characterization in both the Middle East and North Africa. In this paper, we focus on demonstrating and validating our current modeling capabilities, which include reflectivity, boundary integral, finite-difference, along with hybrid forms of these approaches. We use the boundary integral and finite-difference techniques to provide better understanding of regional discriminant variability along three arrays which were deployed to record regional signals from the NPE. These arrays extend west, northwest, and east from NTS, with the western line coinciding with one of three Southern Sierra Continental Dynamics (SSCD) refraction experiment profiles. This gives detailed coverage of regional phases along one of the most well constrained crustal profiles in the western United States. Phase amplitudes and the resulting discriminant variability are presented. This ``ground truth`` dataset will then act as the basis for the future validation of our numerical codes concurrent with our regionalization of the Middle East and North Africa.
Date: July 1, 1995
Creator: Schultz, C.A.; Larsen, S.C.; Goldstein, P. & Ruppert, S.D.
Partner: UNT Libraries Government Documents Department

Seismic results from DOE`s non-proliferation experiment: A comparison of chemical and nuclear explosions

Description: The basic results from the US Department of Energy`s (DOE`s) NonProliferation Experiment (NPE) for seismic signal generation are that the source function for a chemical explosion is equivalent to that of a nuclear explosion of about twice the yield and that the seismic moment measurements are consistent between freefield, local, and regional measurements. In addition, evidence was found that Pn in the Basin and Range province of the western United States is a turning ray and is simply proportional to the source function while the transfer functions for Pg and Lg are low-pass in nature.
Date: January 1, 1995
Creator: Denny, M.; Goldstein, P.; Mayeda, K. & Walter, W.
Partner: UNT Libraries Government Documents Department

Preliminary report on the implications of mining practices in an open-pit gold mine for monitoring of a comprehensive Test Ban Treaty

Description: This report summarizes the preliminary results of an ongoing experiment at the Gold Quarry pit, operated by the Newmont Gold Company at Carlin, NV. The purpose of the experiment is to obtain local and regional seismic data together with ``ground truth``, from conventional surface blasting activity and to use these data to help determine the effectiveness with which conventional mining blasts can be discriminated from underground nuclear explosions.
Date: July 1, 1995
Creator: Jarpe, S.P.; Goldstein, P.; Moran, B. & Glenn, L.A.
Partner: UNT Libraries Government Documents Department

Depth and source mechanism estimation for special event analysis, event screening, and regional calibration

Description: We have summarized the advantages and disadvantages of a variety of techniques for depth and mechanism estimation and suggest that significant work remains to be done for events with magnitudes of interest for test ban monitoring. We also describe a new, waveform modeling-based tool for fast and accurate, high-resolution depth and mechanism estimation. Significant features of this tool include its speed and accuracy and its applicability at relatively high frequencies. These features allow a user to rapidly determine accurate, high-resolution depth estimates and constraints on source mechanism for relatively small magnitude (mb-4.5) events. Based on the accuracy of depth estimates obtained with this tool, we conclude it is useful for both the analysis of unusual or suspect events and for event screening. We also find that this tool provides significant constraints on source mechanism and have used it to develop ''ground-truth'' estimates of depth and mechanism for a set of events in the Middle East and North Africa. These ''ground-truth'' depths and mechanisms should be useful for regional calibration.
Date: July 23, 1999
Creator: Goldstein, P; Dodge, D; Ichinose, Rodgers, A; Bhattacharyya, B & Leach, R
Partner: UNT Libraries Government Documents Department

Regional seismic discrimination research at LLNL

Description: 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.
Date: October 1, 1995
Creator: Walter, W.R.; Mayeda, K.M.; Goldstein, P.; Patton, H.J.; Jarpe, S. & Glenn, L.
Partner: UNT Libraries Government Documents Department

Advances in National Capabilities for Consequence Assessment Modeling of Airborne Hazards

Description: This paper describes ongoing advancement of airborne hazard modeling capabilities in support of multiple agencies through the National Atmospheric Release Advisory Center (NARAC) and the Interagency Atmospheric Modeling and Atmospheric Assessment Center (IMAAC). A suite of software tools developed by Lawrence Livermore National Laboratory (LLNL) and collaborating organizations includes simple stand-alone, local-scale plume modeling tools for end user's computers, Web- and Internet-based software to access advanced 3-D flow and atmospheric dispersion modeling tools and expert analysis from the national center at LLNL, and state-of-the-science high-resolution urban models and event reconstruction capabilities.
Date: November 26, 2007
Creator: Nasstrom, J; Sugiyama, G; Foster, K; Larsen, S; Kosovic, B; Eme, B et al.
Partner: UNT Libraries Government Documents Department

On the sensitivity of broadband regional seismic phases to multi-dimensional earth structure: implications for phase identification

Description: We have developed and are utilizing state-of-the-art, elastic wave propagation modeling capabilities to understand the physical basis of regional wave propagation phenomena. Understanding the physical basis of these phenomena is essential for developing transportable seismic identification techniques and for predicting the behavior of regional phases in relatively aseismic regions. Based on modeling of data in the vicinity of the Eastern Mediterranean, we find that regional phases (body waves, guided waves, and surface waves) are very sensitive to the existence of deep sedimentary basins. Crustal thinning also affects the regional body and guided waves but to a much lesser degree.
Date: July 23, 1999
Creator: Bhattacharyya, J; Dodge, D; Goldstein, P; Ichinose, G; Larsen, S; Leach, R et al.
Partner: UNT Libraries Government Documents Department

Signatures of testing: On-site inspection technologies

Description: This paper describes the phenomenology of nuclear explosions and technologies for their detection as relevant to On-Site Inspection (OSI) for a comprehensive test-ban (CTB). Our experience with the US nuclear test program which has been primarily carried out at the Nevada Test Site (NTS) and in the Pacific Ocean. The goals of OSI are to resolve ambiguous events, reduce uncertainty, deter attempts at evasion, and provide responsive and technically competent means of confirming the occurrence of a nuclear explosion should deterrence fail. These goals would include finding evidence of an evasive nuclear explosion or evidence that the event was non-nuclear, such as an earthquake or large chemical explosion.
Date: January 1, 1995
Creator: Zucca, J.J.; Carrigan, C.; Goldstein, P.; Jarpe, S.P.; Sweeney, J.; Pickles, W.L. et al.
Partner: UNT Libraries Government Documents Department

Technical Integration of Defense Threat Reduction Agency (DTRA) Location Related Funded Projects into the DOE Knowledge Base

Description: This document directly reviews the current Defense Threat Reduction Agency (DTRA) PRDA contracts and describes how they can best be integrated with the DOE CTBT R&amp;D Knowledge Base. Contract descriptions and numbers listed below are based on the DOE CTBT R&amp;D Web Site - http://www.ctbt.rnd.doe.gov. More detailed information on the nature of each contract can be found through this web site. In general, the location related PRDA contracts provide products over a set of categories. These categories can be divided into five areas, namely: Contextual map information; Reference event data; Velocity models; Phase detection/picking algorithms; and Location techniques.
Date: March 14, 2000
Creator: Schultz, C.A.; Bhattacharyya, J.; Flanaga, M.; Goldstein, P.; Myers, S. & Swenson, J.
Partner: UNT Libraries Government Documents Department