Threshold magnitudes for a multichannel correlation detector in background seismicity

doi:10.1785/0120150191

Title: Threshold magnitudes for a multichannel correlation detector in background seismicity

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Abstract

Colocated explosive sources often produce correlated seismic waveforms. Multichannel correlation detectors identify these signals by scanning template waveforms recorded from known reference events against "target" data to find similar waveforms. This screening problem is challenged at thresholds required to monitor smaller explosions, often because non-target signals falsely trigger such detectors. Therefore, it is generally unclear what thresholds will reliably identify a target explosion while screening non-target background seismicity. Here, we estimate threshold magnitudes for hypothetical explosions located at the North Korean nuclear test site over six months of 2010, by processing International Monitoring System (IMS) array data with a multichannel waveform correlation detector. Our method (1) accounts for low amplitude background seismicity that falsely triggers correlation detectors but is unidentifiable with conventional power beams, (2) adapts to diurnally variable noise levels and (3) uses source-receiver reciprocity concepts to estimate thresholds for explosions spatially separated from the template source. Furthermore, we find that underground explosions with body wave magnitudes m_b = 1.66 are detectable at the IMS array USRK with probability 0.99, when using template waveforms consisting only of P -waves, without false alarms. We conservatively find that these thresholds also increase by up to a magnitude unit for sources locatedmore »« less

Authors:

Carmichael, Joshua D. ^[1]; Hartse, Hans ^[1]

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Publication Date:: 2016-04-01

Research Org.:: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1255954

Report Number(s):: LA-UR-15-24681
Journal ID: ISSN 0037-1106

Grant/Contract Number:: AC52-06NA25396

Resource Type:: Accepted Manuscript

Journal Name:: Bulletin of the Seismological Society of America

Additional Journal Information:: Journal Volume: 106; Journal Issue: 2; Journal ID: ISSN 0037-1106

Publisher:: Seismological Society of America

Country of Publication:: United States

Language:: English

Subject:: 54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; 97 MATHEMATICS AND COMPUTING; 98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION; continuous threshold monitoring; seismology; cross correlation; statistical signal processing; International Monitoring System; test ban treaty verification; North Korea

Citation Formats


                    Carmichael, Joshua D., and Hartse, Hans. Threshold magnitudes for a multichannel correlation detector in background seismicity.  United States: N. p., 2016. 
        Web.  doi:10.1785/0120150191.

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                    Carmichael, Joshua D., & Hartse, Hans. Threshold magnitudes for a multichannel correlation detector in background seismicity.  United States.  doi:10.1785/0120150191.

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                    Carmichael, Joshua D., and Hartse, Hans. Fri .  
        "Threshold magnitudes for a multichannel correlation detector in background seismicity".  United States.  doi:10.1785/0120150191.  https://www.osti.gov/servlets/purl/1255954.

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@article{osti_1255954,

  title        = {Threshold magnitudes for a multichannel correlation detector in background seismicity},

  author       = {Carmichael, Joshua D. and Hartse, Hans},

  abstractNote = {Colocated explosive sources often produce correlated seismic waveforms. Multichannel correlation detectors identify these signals by scanning template waveforms recorded from known reference events against "target" data to find similar waveforms. This screening problem is challenged at thresholds required to monitor smaller explosions, often because non-target signals falsely trigger such detectors. Therefore, it is generally unclear what thresholds will reliably identify a target explosion while screening non-target background seismicity. Here, we estimate threshold magnitudes for hypothetical explosions located at the North Korean nuclear test site over six months of 2010, by processing International Monitoring System (IMS) array data with a multichannel waveform correlation detector. Our method (1) accounts for low amplitude background seismicity that falsely triggers correlation detectors but is unidentifiable with conventional power beams, (2) adapts to diurnally variable noise levels and (3) uses source-receiver reciprocity concepts to estimate thresholds for explosions spatially separated from the template source. Furthermore, we find that underground explosions with body wave magnitudes mb = 1.66 are detectable at the IMS array USRK with probability 0.99, when using template waveforms consisting only of P -waves, without false alarms. We conservatively find that these thresholds also increase by up to a magnitude unit for sources located 4 km or more from the Feb.12, 2013 announced nuclear test.},

  doi          = {10.1785/0120150191},

  journal      = {Bulletin of the Seismological Society of America},

  number       = 2,

  volume       = 106,

  place        = {United States},

  year         = {2016},

  month        = {4}

}

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