| Regionalized Maximum Likelihood Surface Wave Analysis |
SEP 96 |
27 pages |
| Authors:
J. L. Stevens; K. L. McLaughlin; S-CUBED LA JOLLA CA
|
 | We develop a method for regionalization of surface wave magnitudes, replacing the traditional Ms measurement with a new type of magnitude, the scalar moment, derived from the equations for surface waves from point sources in layered media. This has the effect of minimizing the frequency dependence and distance dependence of the magnitude, and allows worldwide regionalization so that the magnitude is a consistent measure of source size for any source ... |
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| Modeling and Post Mission Data Analysis |
20 JUN 96 |
37 pages |
| Authors:
V. A. Davis; S-CUBED LA JOLLA CA
|
| This report describes work performed to do analysis in support of three Phillips laboratory flight experiments. The PASP Plus effort is an examination of the interactions of the PASP Plus spacecraft and test solar cells with the low-energy plasma environment. The SPREE effort is the use of comparison with flight data to examine, improve, and validate sheath and electron collection models and to examine some of the interactions that determine ... |
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| Xnice: A System for Assessing Network Identification Performance |
MAY 96 |
138 pages |
| Authors:
T. G. Barker; S-CUBED LA JOLLA CA
|
| This report describes a computer system for evaluating the ability of a network to detect and identify seismic sources. The program, called Xnice, for Network Identification Capability Evaluation running under an X-windows interface, has a complete graphics interface for setting the parameters of simulations and evaluating the results. The performance of both regional and teleseismic discriminants can be easily examined. We describe here the use of the program, including a ... |
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| Further Studies of the Seismic Characteristics of Russian Explosions in Cavities: Implications for Cavity Decoupling of Underground Nuclear Explosions |
JAN 96 |
79 pages |
| Authors:
J. R. Murphy; I. O. Kitov; N. Rimer; D. D. Sultanov; B. W. Barker; S-CUBED LA JOLLA CA
|
| This report provides a summary of the results of a joint research program under which scientists from S-CUBED have been working with scientists from the Russian Institute for Dynamics of the Geospheres in an attempt to develop a better understanding of the effects of cavity decoupling on the seismic signals produced by underground nuclear explosions. Investigations conducted under this program have focused on analyses of seismic data recorded from a ... |
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| Investigations of the Seismic Characteristics of Rockbursts |
DEC 95 |
89 pages |
| Authors:
Theron J. Bennett; Keith L. McLaughlin; Margaret E. Marshall; Brian W. Barker; John R. Murphy; S-CUBED LA JOLLA CA
|
| This research is directed at improving understanding of rockbursts and related mine tremors as seismic sources and at distinguishing them from other source types based on characteristics of their signals. In addition, this effort seeks to gain insight into controllability of rockbursts and its relevance to possible clandestine testing of small nuclear explosions. An observational element of this research has focused on identifying the characteristics of the seismic signals from ... |
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| Equation of State Modeling for HYDROPLUS |
01 SEP 95 |
31 pages |
| Authors:
Stephen Peyton; S-CUBED LA JOLLA CA
|
| This report reviews the theoretical foundation for the non- equilibrium equation of state for silicate rocks, and documents the parametric computational equation so state developed by S-Cubed for the DNA HYDROPLUS methodology. Model results for BEXAR rhyolite are presented. |
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| A Transportable Regional Discriminant Using a Maximum Likelihood Analysis of Surface Waves, |
14 AUG 1995 |
1 pages |
| Authors:
J. L. Stevens; K. L. McLaughlin; S-CUBED LA JOLLA CA
|
| The objective of this research is to develop a robust extension of the mb:Ms discriminant that is: (1) transportable from region to region, (2) optimizeable for each region, (3) frequency independent, (4) usable at regional and teleseismic distances, (5) applicable to small magnitude events, (6) able to determine an upper bound in the absence of surface wave data, (7) robust with respect to regional variations and operational considerations, (8) usable ... |
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| Efficient Calculation of Regional Synthetic Seismograms, |
14 AUG 1995 |
1 pages |
| Authors:
K. L. McLaughlin; S-CUBED LA JOLLA CA
|
| The general behavior of regional seismograms as a function of source type, depth, distance, and frequency is not generally available in many regions of the world where seismic and human activity has not previously provided an empirical base of earthquakes, nuclear explosions, industrial blasts, mine bumps, and rockbursts. Under these circumstances, it is expected that discrimination practice may rely in part on theoretical transportation of discriminants tested in other regions ... |
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| Calibration of Local Magnitude Scales for Use in Seismic Monitoring. |
AUG 1995 |
58 pages |
| Authors:
J. R. Murphy; M. E. Marshall; B. W. Barker; T. J. Bennett; L. T. Grant; S-CUBED LA JOLLA CA
|
| In situations where cavity decoupling of underground nuclear explosions is a plausible evasion scenario, comprehensive seismic monitoring of any eventual CTBT will require the routine identification of many small seismic events with magnitudes in the range 2.0 < m sub b < 3.5. However, since such events are not expected to be detected teleseismically, their magnitudes will have to be estimated from regional recordings using seismic phases and frequency bands ... |
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| Modeling and Post Mission Data Analysis |
29 JUN 95 |
111 pages |
| Authors:
V. A. Davis; B. M. Gardner; S-CUBED LA JOLLA CA
|
| This report describes work performed during the second year of a contract do analysis in support of three Phillips laboratory flight experiments. The PAsP Plus effort is an examination of the interactions of the PAsP Plus spacecraft and test solar cells with the low-energy plasma environment. This report describes work to develop an analytical model of parasitic current and a preliminary examination of some of the flight data. The SPREE ... |
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| Analyses of the Seismic Characteristics of U.S. and Russian Cavity Decoupled Explosions |
NOV 94 |
66 pages |
| Authors:
J. R. Murphy; I. O. Kitov; J. L. Stevens; D. D. Sultanov; B. W. Barker; S-CUBED LA JOLLA CA
|
| This report presents a summary of the initial results of an on-going joint research program in which S-CUBED scientists are working with Russian scientists from the Institute for Dynamics of the Geospheres in an attempt to develop a better understanding of the effects of cavity decoupling on the seismic signals produced by underground nuclear explosions. This program includes analyses of seismic data recorded from a series of 10 tamped and ... |
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| Analyses of the Seismic Characteristics of U.S. and Russian Cavity Decoupled Explosions |
NOV 94 |
66 pages |
| Authors:
J. R. Murphy; I. O. Kitov; J. L. Stevens; D. D. Sultanov; B. W. Barker; S-CUBED LA JOLLA CA
|
| This report presents a summary of the initial results of an on-going joint research program in which S-CUBED scientists are working with Russian scientists from the Institute for Dynamics of the Geospheres in an attempt to develop a better understanding of the effects of cavity decoupling on the seismic signals produced by underground nuclear explosions. This program includes analyses of seismic data recorded from a series of 10 tamped and ... |
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| Development of a Geophysical Data Fusion System for Assessment and Remediation Studies of Polluted Groundwater Aquifers |
OCT 94 |
38 pages |
| Authors:
J. R. Murphy; D. C. O'Neill; B. W. Barker; S-CUBED LA JOLLA CA
|
| The research described in this report is directed toward the development of a workstation-based data management, analysis and visualization system which can be used to improve the Air Force's capability to evaluate site specific environmental hazards. The initial prototype system described in this report is directed toward a specific application to the Massachusetts Military Reservation (formerly Otis Air Force Base) on Cape Cod, Massachusetts. This system integrates a comprehensive, on-line ... |
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| Network Identification Capability Evaluation (NICE) of Regional Networks |
JUL 94 |
51 pages |
| Authors:
T. G. Barker; K. L. McLaughlin; J. L. Stevens; S-CUBED LA JOLLA CA
|
| The computer program NICE, for Network Identification Capability Evaluation, was written to assess the ability of a seismic network to discriminate earthquakes from explosions. In this report on the progress during the first phase of a two-year project, we describe enhancements to the program which allow assessment of regional networks and discriminants. The enhanced program, called XCNICE simulates the detection, location and identification of a suite of events using a ... |
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| Modeling and Post Mission Data Analysis |
08 JUN 94 |
115 pages |
| Authors:
V. A. Davis; M. J. Mandell; S-CUBED LA JOLLA CA
|
| This report described work performed during the first year of a contract to do analysis in support of three Phillips Laboratory flight experiments. The PASP Plus effort is an examination of the interactions of the PASP Plus spacecraft and test solar cells with the low-energy plasma environment. This report describes calculations done to assist in determinations of the PASP Plus floating potential. The SPREE effort is the use of comparisons ... |
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| Numerical Simulation of Quarry Blast Sources |
01 JAN 94 |
25 pages |
| Authors:
Keith L. McLaughlin; T. G. Barker; J. L. Stevens; S-CUBED LA JOLLA CA
|
| This final report summarizes the principal results of numerical investigations of the quarry blast as a seismic source. The goal was to derive simple but physically meaningful models that could be used to predict regional and teleseismic waveforms for large industrial blasts. The source models may then be used to develop seismic discrimination strategies for the identification of industrial blasts and other natural and man made seismic sources. Physical models ... |
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| Seismic Identification Analyses of Cavity Decoupled Nuclear and Chemical Explosions |
JAN 94 |
82 pages |
| Authors:
John R. Murphy; Brian W. Barker; S-CUBED LA JOLLA CA
|
| Successful seismic monitoring of any eventual Comprehensive Test Ban Treaty will require development of a capability to identify signals from small cavity decoupled nuclear explosions from among numerous signals to be expected from earthquakes, rockbursts and chemical explosion (CE) events of comparable magnitude. The investigations summarized in this report focus on preliminary studies which have been carried out in an attempt to distinguish between decoupled nuclear explosions and CE events ... |
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| Data Analysis Support for the SPREE Instruments on the TSS-1 Shuttle Flight |
11 AUG 93 |
32 pages |
| Authors:
I. Katz; M. J. Mandell; S-CUBED LA JOLLA CA
|
| The objective of this contract is a scientific study of the interactions between the first flight of the Tethered Satellite System (TXX-1) and the ionosphere to increase understanding of the structure and current characteristics of high-voltage sheaths in the ionosphere. A paper describing the results of a review of the data sets for evidence of presheath heating around the subsatellite is included. |
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| Data Analysis Support for the SPREE Instruments on the TSS-1 Shuttle Flight. |
11 AUG 1993 |
|
| Authors:
I. Katz; M. J. Mandell; S-CUBED LA JOLLA CA
|
 | The objective of this contract is a scientific study of the interactions between the first flight of the Tethered Sateillite System (TXX-1) and the ionosphere to increase understanding of the structure and current characteristics of high-voltage sheaths in the ionosphere. A paper describing the results of a review of the data sets for evidence of presheath heating around the subsatellite is included. |
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| Development of a Comprehensive Seismic Yield Estimation System for Underground Nuclear Explosions |
MAY 93 |
117 pages |
| Authors:
Jack R. Murphy; Jeffrey L. Stevens; D. C. O'Neill; B. W. Barker; Keith L. McLaughlin; S-CUBED LA JOLLA CA
|
| This report summarizes the research which has been carried out in conjunction with the development of a comprehensive new seismic yield estimation system (YES) for underground nuclear explosions. Specifically, it provides a detailed description of the final version of YES which has been implemented at the ARPA Center for Seismic Studies (CSS) to estimate seismic yields of explosions at the Shagan River and Novaya Zemlya test sites of the former ... |
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| Numerical Simulation of Quarry Blast Sources |
01 JAN 93 |
66 pages |
| Authors:
T. G. Barker; K. L. McLaughlin; J. L. Stevens; S-CUBED LA JOLLA CA
|
| Quarry blast sources are developed based on well-documented blasting practices from decades of blasting in quarries and used to simulate seismic signals from quarry blasts, and to examine the 'hide-in-quarry blast' scenario for evading detection of nuclear weapons testing. Blasting is designed to break rock through spallation, and the resultant spall is an important part of the quarry blast source. The quarry blast source models include the finite size of ... |
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| Seismic Characteristics of Rockbursts for Use in Discrimination |
JAN 93 |
104 pages |
| Authors:
Theron J. Bennett; James F. Scheimer; Antoinette K. Campanella; John R. Murphy; S-CUBED LA JOLLA CA
|
| This research program is aimed at characterizing the seismic behavior of rockbursts and other stress-release events associated with mining for use in their discrimination. The frequent occurrence of rockbursts in mining areas throughout the world could present problems for routine discrimination at low thresholds. In addition, the possibility of controlling rockbursts in some mining areas may provide the opportunity to conceal a small or decoupled nuclear explosion test. Review of ... |
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| Seismic Characteristics of Rockbursts for Use in Discrimination. |
JAN 1993 |
|
| Authors:
Theron J. Bennett; James F. Scheimer; Antoinette K. Campanella; John R. Murphy; S-CUBED LA JOLLA CA
|
| This research program is aimed at characterizing the seismic behavior of rockbursts and other stress-release events associated with mining for use in their discrimination. The frequent occurrence of rockbursts in mining areas throughout the world could present problems for routine discrimination at low thresholds. In addition, the possibility of controlling rockbursts in some mining areas may provide the opportunity to conceal a small or decoupled nuclear explosion test. Review of ... |
|
| Spacecraft Surface Charging Handbook |
NOV 92 |
352 pages |
| Authors:
V. A. Davis; L. W. Gordon; S-CUBED LA JOLLA CA
|
| Spacecraft surface charging is the buildup of net electric charge-- and therefore electrostatic potential--on the external surfaces of a spacecraft due to incident particles with energies in the kilo-electron volt to tens of kilo-electron volts range. Geosynchronous and low-altitude, polar-orbiting spacecraft encounter charging environments. Surface charging causes problems for operational spacecraft. A primary effect is the occurrence of electronic switching anomalies which can be triggered by differential charging related discharges. ... |
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| Data Analysis Support for the Shuttle Potential and Return Electron Experiment (SPREE) on the Tethered Satellite System 1 (TSS-1) Flight |
29 JUN 92 |
94 pages |
| Authors:
M. J. Mandell; I. Katz; V. A. Davis; G. A. Jongeward; S-CUBED LA JOLLA CA
|
| This report describes the second year of a scientific study of the interactions between the first flight of the Tethered Satellite System (TSS-1) and the ionosphere to increase understanding of the structure and current characteristics of high-voltage sheaths in the ionosphere. The investigations described here include an examination of electron collection and presheath structure by a positively biased, conducting sphere in the ionosphere moving at orbital velocity, including the effects ... |
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| Analysis of Dynamical Plasma Interactions with High-Voltage Spacecraft |
JUN 92 |
183 pages |
| Authors:
M. J. Mandell; T. Luu; J. Lilley; G. Jongeward; I. Katz; S-CUBED LA JOLLA CA
|
| This volume describes numerous plasma interaction problems done in support of DynaPAC code development, and in support of the SPEAR-II and SPEAR-3 programs. Two dimensional calculations show that oscillations of a beam emitted into an underdense plasma can cause overcharging of a beam emitting rocket, as was observed on MAIMIK. The effects of the sheath instability caused by orbital motion of a positive body are studied, showing that substantial potential ... |
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| Analysis of Dynamical Plasma Interactions with High-Voltage Spacecraft |
JUN 92 |
128 pages |
| Authors:
M. J. Mandell; T. Luu; J. Lilley; S-CUBED LA JOLLA CA
|
| This volume is the users' and programmers' manual for the DynaPAC computer code. DynaPAC is a user-friendly and programmer-friendly workbench for studying plasma interactions with realistic spacecraft in three dimensions. DynaPAC enables plasma interactions specialists to perform predictive scientific calculations with direct application to engineering problems. DynaPAC uses a finite element algorithm with strictly continuous electric fields for accurate potential calculation and particle tracking, and contains a powerful database utility ... |
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| Analysis of the Dynamical Plasma Interactions with High-Voltage Spacecraft. |
JUN 1992 |
|
| Authors:
M. J. Mandell; T. Luu; J. Lilley; G. Jongeward; I. Katz; S-CUBED LA JOLLA CA
|
| This volume describes numerous plasma interaction problems done in support of DynaPAC code development, and in support of the SPEAR-II and SPEAR-3 programs. Two dimensional calculations show that oscillations of a beam emitted into an underdense plasma can cause overcharging of a beam emitting rocket, as was observed on MAIMIK. The effects of the sheath instability caused by orbital motion of a positive body are studied, showing that substantial potential ... |
|
| Demonstration of Regional Discrimination of Eurasian Seismic Events Using Observations at Soviet IRIS and CDSN Stations |
MAR 92 |
123 pages |
| Authors:
Theron J. Bennett; Antoinette K. Campanella; James F. Scheimer; John R. Murphy; S-CUBED LA JOLLA CA
|
| This study has brought together a large, high-quality database of regional signals from Eurasian seismic events, including 38 underground nuclear explosions and 68 earthquakes, recorded at Soviet IRIS and CDSN stations. Characteristics of regional phases observed at each of the Soviet IRIS stations and their relation to propagation and source effects have been analyzed. The high quality of the signals indicates the strong potential of the stations for monitoring events ... |
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| Development of a Comprehensive Seismic Yield Estimation System for Underground Nuclear Explosions |
MAR 92 |
112 pages |
| Authors:
J. R. Murphy; J. N. Jenab; S-CUBED LA JOLLA CA
|
| This report summarizes progress which has been achieved during the past year in the development of a comprehensive new seismic yield estimation system (YES) for underground nuclear explosions. Specifically, a prototype version of YES which is applicable to explosions at the Soviet Shagan River and Novaya Zemlya test sites is described in detail. In its current configuration, the YES encompasses a database of more than 10,000 digital seismograms recorded at ... |
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| Three-Dimensional Finite Difference Modeling of Surface Wave Propagation Across the Barents Shelf |
OCT 91 |
|
| Authors:
K. L. McLaughlin; T G. Barker; J. L. Stevens; B. Shkoller; S. M. Day; S-CUBED LA JOLLA CA
|
| A three-dimensional (3D) finite difference simulation has been conducted of surface waves propagating across a laterally heterogeneous velocity and density model of the Barents Shelf. The 3D model encompasses a region of 1620 by 810 km to a depth of 210 km. The calculations were designed to model 0. 02 to 0.05 Hz surface waves from an isotropic source at Novaya Zemlya in a 3D heterogeneous model. Extensive focusing/defocusing of ... |
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| Two-Dimensional Axisymmetric Calculations of Surface Waves Generated by an Explosion in an Island, Mountain and Sedimentary Basin |
OCT 91 |
50 pages |
| Authors:
J. L. Stevens; K. L. McLaughlin; S. M. Day; B. Shkoller; S-CUBED LA JOLLA CA
|
| The generation of long period (20-50 second) surface waves by an explosion on an island, inside a mountain, or near a material discontinuity is studied using two-dimensional axisymmetric finite difference calculations. The generation of surface waves can be reduced substantially if the explosion is close to a vertical boundary such as a material velocity reduction, mountain slope, or island/ocean boundary. This occurs because the horizontal components of the static stress ... |
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| Data Analysis Support for the Shuttle Potential and Return Electron Experiment (SPREE) on the Tethered Satellite System 1 (TSS-1) Flight |
24 JUN 91 |
126 pages |
| Authors:
T. T. Luu; V. A. Davis; J. R. Lilley; I. Katz; S-CUBED LA JOLLA CA
|
| This study describes the interactions between the first flight of the Tethered Satellite System (TSS-1) and the ionosphere to increase understanding of the structure and current characteristics of high-voltage sheaths in the ionosphere. The investigations described here include a determination of the tether current and voltages, an evaluation of the shuttle orbiter ion collection, the ion current detected by the SPREE instrumentation, and the effect of the subsatellite thrusters on ... |
|
| Development of a Comprehensive Seismic Yield Estimation System for Underground Nuclear Explosions |
MAY 91 |
36 pages |
| Authors:
J. R. Murphy; J. L. Stevens; D. C. O'Neill; B. W. Barker; K. L. McLaughlin; S-CUBED LA JOLLA CA
|
| This report summarizes the progress which has been achieved during the past year in the development of a comprehensive new seismic yield estimation system for underground nuclear explosions. Specifically, a preliminary prototype version of this system, which has now been successfully implemented at the DARPA Center for Seismic Studies (CSS), is described in detail and its functionality is graphically illustrated through a sample application to the seismic data recorded from ... |
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| Two and Three Dimensional Numeical Modeling of Surface Waves from Underground Explosions, Analysis of Data from the Soviet JVE, and Magnitude/ Yield Relations for East Kazakh Explosions |
JAN 91 |
58 pages |
| Authors:
K. L. McLaughlin; T. G. Barker; S. M. Day; B. Shkoller; J. L. Stevens; S-CUBED LA JOLLA CA
|
| We perform three dimensional finite difference simulation of surface waves generated at the Amchitka test site and find that the Aleutian arc structure causes higher amplitudes to the east relative to the north and south, and that this structure can also generate rapid amplitude changes over a small range of azimuths and generate Love waves with substantial amplitudes. A series of two-dimensional finite difference simulations show that long period surface ... |
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| Effects of Subduction Zone Structure on the Propagation of Explosion- Generated Long-Period Rayleigh Waves |
JAN 91 |
|
| Authors:
K. L. McLaughlin; T. G. Barker; S. M. Day; B. Shkoller; J. L. Stevens; S-CUBED LA JOLLA CA
|
| 3D linear elastic finite difference calculations were used to investigate effects of near-source scattering on long-period surface waves radiated by shallow explosions located in the arc of a subduction zone. These simulations were motivated by the teleseismic Rayleigh-wave amplitude patterns of explosions detonated at the Amchitka test site. Amplitude patterns of these explosion-generated 20-40 second surface waves show evidence of both tectonic release and source-receiver path effects. A 3D velocity ... |
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| Regional Discrimination Research and Methodology Implementation: Analyses of CDSN and Soviet IRIS Data |
JUL 90 |
|
| Authors:
T. J. Bennett; J. F. Scheimer; A. K. Campanella; J. R. Murphy; S-CUBED LA JOLLA CA
|
| 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 ... |
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| An Analysis of the Effects of Spall on Regional and Teleseismic Waveforms Using Two-Dimensional Numerical Modeling of Underground Explosions |
MAY 90 |
|
| Authors:
T. G. Barker; S. M. Day; K. L. McLaughlin; B. Shkoller; J. L. Stevens; S-CUBED LA JOLLA CA
|
| A simple, physical model for spall is developed by comparing the waveforms from two-dimensional explosion simulations with the waveforms generated by a one-dimensional explosion plus a shallow tension crack in the same layered medium. The tension crack is parameterized by its radius, depth, and a distribution of takeoff velocities over its surface. This model accurately reproduces the P-waves from the two-dimensional simulations. The parameters for the spall model a ... |
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| Implications of Explosion Generated Spall Models: Regional Seismic Signals |
MAY 90 |
|
| Authors:
K. L. McLaughlin; T. G. Barker; S. M. Day; S-CUBED LA JOLLA CA
|
| The contribution of the spall source to the short period regional explosion seismogram is studied using new parametric models for the spallation seismic source derived from (2-D) axisymmetric nonlinear finite difference simulations for underground nuclear explosions. It is concluded that in high- velocity crustal structures spall may be a significant source of short period Lg and may significantly affect the Pg excitation. Regional phase excitation from a vertical point force ... |
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| A Simple Physical Model for Spall from Nuclear Explosions Based Upon Two-Dimensional Nonlinear Numerical Simulations |
MAY 90 |
|
| Authors:
T. G. Barker; S. M. Day; S-CUBED LA JOLLA CA
|
| Examine the effect of spall on the source function for explosion waveforms using two-dimensional nonlinear numerical simulations of explosions. A simple, physical model for spall is developed by comparing the complete two- dimensional waveform with the waveform generated by a one-dimensional explosion plus a shallow tension crack in teh same layered medium. This is an extension to higher frequencies of the spall model. The tension crack is parameterized by its ... |
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| Pre-Shock Soil Temperature Predictions of a Simplified Soil Heating Model |
01 MAR 90 |
|
| Authors:
Burton E. Freeman; Purna C. Patnaik; S-CUBED LA JOLLA CA
|
| A model of energy transport and temperature evolution in the surface layers of soil subjected to thermal radiation prior to the time-of-arrival (TOA) of the blastwave from a low height-of-burst (HOB) nuclear explosion has been developed and evaluated. Processes taken into account are thermal conductivity, boiling of water, transpiration cooling, and attenuation of thermal radiation in the soil. Calculations were carried out for a range parameters. We present an analytic ... |
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| Streak Damping |
01 DEC 89 |
|
| Authors:
J. Baker; S. Peyton; H. Freiberg; S-CUBED LA JOLLA CA
|
| This report documents a study aimed at improving the damping in STREAK. We recommend a form and value for an artificial viscosity which appears to control ringing and overshoots without overdamping. Keywords: Streak computer program; Misty echo shot; Shock; Artificial viscosity; Damping. (jhd) |
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| POLAR User's Manual |
OCT 89 |
|
| Authors:
John R. Lilley Jr.; David L. Cooke; Gary A. Jongeward; Ira Katz; S-CUBED LA JOLLA CA
|
| This report documents the physical principles and computational algorithms of the POLAR code. POLAR models in three dimensions the interactions of large spacecraft with the plasma environment in low polar orbit. It includes models of space charge limited particle collection, satellite wakes, the polar auroral environment, magnetic field effects, spacecraft surface charging, particle beam effects, and sheath ionization. |
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| Polar Code Validation |
30 SEP 89 |
|
| Authors:
I. Katz; J. R. Lilley Jr.; G. A. Jongeward; M. J. Mandell; T. T. Luu; S-CUBED LA JOLLA CA
|
| The POLAR code was written to model charging by large spacecraft in low, polar orbit. This report documents comparisons of POLAR code calculations with flight experiments. Calculations of the plasma wake behind the Shuttle Orbiter are compared with the situ measurements of Murphy et al. 1989. Calculations of the charging of DMSP-7, performed by Dr. David Cooke for the GL, are compared with the flight measurements of Gussenhoven et al. ... |
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| Nonlinear Finite Difference Simulations of Cavity Decoupled Explosions in Salt and Tuff |
30 JUN 89 |
|
| Authors:
J. L. Stevens; J. R. Murphy; N. Rimer; S-CUBED LA JOLLA CA
|
| Nonlinear finite difference simulations are performed to model the seismic source functions for decoupled, partially coupled, and overdecoupled explosions in air-filled cavities in salt and unsaturated tuff emplacement media. The tuff simulations are performed in an 11 meter cavity under conditions similar to the Mill Yard experiment. The salt simulations are performed in a 17 meter cavity under conditions similar to the Sterling test. The maximum low frequency decoupling factor ... |
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| Regional Discrimination of Quarry Blasts, Earthquakes and Underground Nuclear Explosions |
07 APR 89 |
|
| Authors:
T. J. Bennett; B. W. Barker; K. L. McLaughlin; J. R. Murphy; S-CUBED LA JOLLA CA
|
| 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, ... |
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| Advanced Constitutive Modeling of Plain and Reinforced Concretes |
31 DEC 88 |
|
| Authors:
G. A. Hegemier; H. E. Head; K. C. Valanis; H. Murakami; S-CUBED LA JOLLA CA
|
| This report summarizes research conducted by S-CUBED to develop advanced constitutive models of plain and reinforced concrete for ultimate use in the cost-effective design and hardness assessment of concrete protective structures. The specific goals of the research are two-fold; namely, (1) development of a mixture theory which can accurately account for steel-concrete interaction and (2) formulation of an advanced constitutive theory for plain concrete which can accurately portray its nonlinear, ... |
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| Effects of Depth of Burial and Tectonic Strain Release on Regional and Teleseismic Explosion Waveforms |
04 NOV 88 |
|
| Authors:
K. L. McLaughlin; T. G. Barker; S. M. Day; B. Shkoller; J. L. Stevens; S-CUBED LA JOLLA CA
|
| The seismic motions from nonlinear two dimensional (2D) axisymmetric finite difference calculations of underground explosions are propagated to regional and teleseismic distances. Synthetic seismograms are computed and examined to study the effects of depth of burial, medium structure, and prestress on seismic waveforms. The elastodynamic representation theorem is used to couple the results of finite difference source calculations to regional Green's functions computed using a wavenumber integration algorithm. The 2D ... |
|
| An Endochronic Plasticity Model for ISST Soils |
MAY 1988 |
78 pages |
| Authors:
K. C. Valanis; H. E. Read; S-CUBED LA JOLLA CA
|
| A new endochronic plasticity model that has the capability to describe both densification and dilatency is described and applied to laboratory data from reconstructed ISST soils generated by the US Army Engineer Waterways Experiment Station. An efficient, explicit numerical scheme is developed for integrating the system of equations which govern the new model, and a corresponding computer program for the numerical scheme is given. In numerical studies conducted with the ... |
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| High Frequency Seismic Source Characteristics of Cavity Decoupled Underground Nuclear Explosions |
MAY 88 |
|
| Authors:
J. R. Murphy; J. L. Stevens; N. Rimer; S-CUBED LA JOLLA CA
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| The research investigated the high frequency characteristics of the seismic sources corresponding to cavity decoupled nuclear explosions and to assess the implications of these investigations with regard to the detection and discrimination of small decoupled explosions. This study has been carried out using a combination of deterministic simulations and analyses of empirical data recorded from selected cavity decoupled explosions. With regard to the deterministic simulations, a series of nonlinear finite ... |
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