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  • 1
    ISSN: 1573-0956
    Keywords: Nuclear explosion detection and recognition ; Seismology ; Remote sensing ; Radioactivity ; Ionospheric effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper reports on a joint meeting of the Royal Astronomical Society's Joint Association for Geophysics and VERTIC (the Verification Technology Information Centre) held in London in 1992. The topics presented focused on the detection and recognition of underground nuclear explosions. The objective of the meeting was to emphasize the multi-methodological approach that is important in verifying compliance with test-ban treaties. An overview of seismological monitoring was followed by a discussion of the technical and scientific aspects of a global seismic monitoring network, and in particular of the 1991 experiment to test the large-scale international exchange of seismic data between recording stations and data centres world-wide. The current capabilities of satellite remote-sensing were presented, and their use explained in terms of both the provision of information for monitoring the development of foreign nuclear testing programmes and also for providing sufficient information for the evaluation of treaty compliance. A review of radio-isotope sampling showed how the isotopic signature of both air and ground based sampling programmes can be diagnostic of the nuclear source. Finally, previously classified research on the ionospheric effects of underground nuclear explosions was presented, the generated acoustic waves disturbing the ionosphere and producing detectable changes in the reflection of radio and radar signals which have potential as a monitoring technique.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-11-04
    Description: The Intelligent Monitoring Systern (IMS) currently provides for joint processing of data from six arrays located in Northern and Central Europe. From experience with analyst review of events automatically defined by the IMS, we bave realized that the quality of the automatic event locations can be significantly improved if the event intervals are reprocessed with signal processing pararneters tuned to phases from events in the given region. The tuned processing parameters are obtained from off line analysis of events located in the region of interest. The primary goal of such intelligent post processing is to provide event definitions of a quality that minimizes the need for subsequent manual analysis. The first step in this post processing is to subdivide the arca to be monitored in order to identify sites of interest. Clearly, calibration will be the easiest and potential savings in manpower are the largest for areas of high, recurring seismicity. We bave identified 8 mining sites in Fennoscandia/NW Russia and noted that 65.6% of the events of ML 〉 2.0 in this region can be associated with one of these sites. This result is based on 1 year and a half of data. The second step is to refine the phase arrival and azimuth estimates using frequency filters and processing parameters that are tuned to the initial event location provided by the IMS. In this study, we have analyzed a set of 52 mining explosions from the Khibiny Massif mining area in the Kola peninsula of Russia. Very accurate locations of these events bave been provided by the seismologists from the Kola Regional Seismology Centre. Using an autoregressive likelihood technique we have been able to estimate onset times to an accuracy (standard deviation) of about 0.05 s for P phases and 0.15 0.20 s for S phases. Using fixed frequency bands, azimuth can be estimated to an accuracy (one standard deviation) of 0.9 degrees for the ARCESS array and 3 4 degrees for the small array recently established near Apatity on the Kola peninsula. The third step in the post processing is a relocation of the event, using refined arrivai times and recomputed azimuths from broad band flk analysis. By introducing region specific travel time corrections, a median error of 1.4 km from the reported location has been obtained. This should be compared to the median error of 10.8 km for the automatie IMS processing for these events. This improvement in location accuracy clearly demonstrates the usefulness of the intelligent post processing approach.
    Description: JCR Journal
    Description: open
    Keywords: seismology ; signal processing ; onset time ; event location ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 3879370 bytes
    Format: application/pdf
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