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Identification of mine collapses, explosions and earthquakes using INSAR: a preliminary investigation

Description: Interferograms constmcted from satellite-borne synthetic aperture radar images have the capability of mapping sub-cm ground surface deformation over areas on the order of 100 x 100 km with a spatial resolution on the order of 10 meters. We investigate the utility of synthetic aperture radar interferomehy (InSAR) used in conjunction with regional seismic methods in detecting and discriminating different types of seismic events in the context of special event analysis for the CTBT. For this initial study, we carried out elastic dislocation modeling of underground explosions, mine collapses and small (M<5.5) shallow earthquakes to produce synthetic interferograms and then analyzed satellite radar data for a large mine collapse. The synthetic modeling shows that, for a given magnitude each type of event produces a distinctive pattern of ground deformation that can be recognized in, and recovered from, the corresponding interferogram. These diagnostic characteristics include not only differences in the polarities of surface displacements but also differences in displacement amplitudes from the different sources. The technique is especially sensitive to source depth, a parameter that is crucial in discriminating earthquakes from the other event types but is often very poorly constrained by regional seismic data alone. The ERS radar data analyzed is from a M<sub>L</sub> 5.2 seismic event that occurred in southwestern Wyoming on February 3,1995. Although seismic data from the event have some characteristics of an underground explosion, based on seismological and geodetic data it has been identified as being caused by a large underground collapse in the Solvay Mine. Several pairs of before-collapse and after-collapse radar images were phase processed to obtain interferograms. The minimum time separation for a before-collapse and after-collapse pair was 548 days. Even with this long time separation, phase coherence between the image pairs was acceptable and a deformation map was successfully obtained. Two images, separated ...
Date: July 7, 1998
Creator: Foxall, B; Sweeney, J J & Walter, W R
Partner: UNT Libraries Government Documents Department

In-Tank Processing (ITP) Geotechnical Summary Report

Description: A geotechnical investigation has been completed for the In Tank Processing Facility (ITP) which consists of buildings 241-96H and 241-32H; and Tanks 241-948H, 241-949H, 241-950H, and 241-951H. The investigation consisted of a literature search for relevant technical data, field explorations, field and laboratory testing, and analyses. This document presents a summary of the scope and results to date of the investigations and engineering analyses for these facilities. A final geotechnical report, which will include a more detailed discussion and all associated boring logs, laboratory test results, and analyses will be issued in October 1994.The purpose of the investigation is to obtain geotechnical information to evaluate the seismic performance of the foundation materials and embankme nts under and around the ITP. The geotechnical engineering objectives of the investigation are to: 1) define the subsurface stratigraphy, 2) obtain representative engineering properties of the subsurface materials, 3) assess the competence of the subsurface materials under static and dynamic loads, 4) derive properties for seismic soil-structure interaction analysis, 5) evaluate the areal and vertical extent of horizons that might cause dynamic settlement or instability, and 6) determine settlement at the foundation level of the tanks.
Date: January 15, 1999
Creator: Cumbest, R. J.
Partner: UNT Libraries Government Documents Department

Representing regional P/S discriminants for event indentification: a comparison of distance corrections, path parameter regressions, cap-averaging and kriging

Description: Short-period regional P/S amplitude ratios hold much promise for discriminating low magnitude explosions from earthquakes in a Comprehensive Test Ban Treaty monitoring context. However, propagation effects lead to variability in regional phase amplitudes that if not accounted for can reduce or eliminate the ability of P/S ratios to discriminate the seismic source. lo this study, several representations of short-period regional P/S amplitude ratios are compared in order to determine which methodology best accounts for the effect of heterogeneous structure on P/S amplitudes. These methodologies are: I) distance corrections, including azimuthal subdivision of the data; 2) path specific crustal waveguide parameter regressions; 3) cap-averaging (running mean smoothing); and 4) kriging. The "predictability" of each method is established by cross-validation (leave-one-out) analysis. We apply these techniques to represent Pn/Lg, Pg/Lg and Pn/Sn observations in three frequency bands (0.75-6.0 Hz) at station ABKT (Alibek, Turkmenistan), site of a primary seismic station of the It~temational Monitoring System (IMS). Paths to ABKT sample diverse crustal stmctores (e.g. various topographic, sedimentary and geologic structures), leading to great variability in the observed P/S amplitude ratios. Subdivision of the data be back-azimuth leads to stronger distance trends than that for the entire data set. This observation alone indicates that path propagation effects due to laterally varying shucture are important for the P/S ratios recorded at ABKT. For these data to be useful for isolating source characteristics, the scatter needs to be reduced by accounting for the path effects and the resulting P/S ratio distribution needs to Gaussian for spatial interpolation and discrimination strategies to be most effective. Each method reduces the scatter of the P/S ratios with varying degrees of success, however kriging has the distinct advantages of providing the greatest variance reduction and a continuous correction surface with an estimate of the model uncertainty. The largest scatter ...
Date: June 18, 1998
Creator: Myers, S C; Rodgers, A J; Schultz, C A & Walter, W R
Partner: UNT Libraries Government Documents Department

Earthquake Risk and U.S. Highway Infrastructure: Frequently Asked Questions

Description: This report addresses frequently asked questions about the risk from earthquakes to highway systems, including bridges, tunnels, pavements, and other highway components. Particular attention is given to highway bridges, which often are the most vulnerable highway structures. The report also discusses federal and nonfederal actions to reduce seismic risk to the U.S. highway system.
Date: March 30, 2011
Creator: Mallett, William J.; Carter, Nicole T. & Folger, Peter
Partner: UNT Libraries Government Documents Department

National Earthquake Engineering Experimental Facility Study: Phase One -- Large Scale Testing Needs

Description: Abstract: This report summarizes information obtained during the first year of a four-year feasibility study for a national earthquake engineering experimental facility. A five-year research program is presented for a national facility in which full-scale or large-scale structures or structural components would be subjected to static or dynamic lateral loads. The facility would have applicability to tests in the following areas: low-rise buildings, medium-rise buildings, high-rise buildings, industrial processing facilities, and power facilities. Representatives from a broad spectrum of professional, industrial, and trade organizations and Federal agencies participated in developing the research program. A comparison of existing testing facilities in the U.S. and other countries engaged in seismic testing and a discussion of international cooperation in large-scale testing are included.
Date: April 1987
Creator: Scribner, Charles F. & Culver, Charles G.
Partner: UNT Libraries Government Documents Department

United States Earthquakes, 1930

Description: Report discussing earthquake activity in the United States during 1930. The report is broken down by regions and has sections for specific earthquakes.
Date: 1932
Creator: Neumann, Frank & Bodle, R. R.
Partner: UNT Libraries Government Documents Department

United States Earthquakes, 1928

Description: Report discussing earthquake activity in the United States during 1928. The report is broken down by regions and has sections for specific earthquakes.
Date: 1930
Creator: Heck, N. H. & Bodle, R. R.
Partner: UNT Libraries Government Documents Department