ISC location procedures

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					International Seismological Centre:
 Providing Data Sets for Scientific
             Research
             István Bondár

       ESC 32nd General Assembly
     Montpellier, September 6-10, 2010
                        Outline
• International   Seismological Centre
• ISC  bulletin
• EHB
• IASPEI Reference Event List
• International Seismographic Station Registry
• Future products




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                               ISC
• International   Seismological Centre
  •   A non-profit, non-governmental entity
  •   Supported by NSF, Royal Society and 55 other
      institutions worldwide
  •   International Seismological Summaries (ISS),
      predecessor of the ISC (1903-1963)
• Mission
  •   Produce the definitive bulletin of the seismicity of the
      Earth
  •   Maintain the International Seismographic Station
      Registry (in cooperation with NEIC)
  •   Host and maintain high-quality data sets openly
      accessible to the scientific community
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                               ISC bulletin
• ISC   bulletin (1960-2010)
  • ~3.5 million reported events, ~1 million ISC solutions
  • ~85 million phases, ~27 million amplitudes
  • ISC bulletin review is 24 months behind real time
  • Since 1999 all reported events are entered into the ISC DB

      Number of events reported/reviewed   Number of associated phases




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Comprehensive ISC Bulletin




   Events reported to the ISC   5
      ISC Bulletin




Events relocated by the ISC   6
                               EHB
• Groomed     ISC bulletin provided by Bob Engdahl
  •   Selected ISC events relocated by the EHB location
      algorithm
  •   More accurate depth and location
  •   Extensively used in seismic tomography studies
• Event   selection criteria
  •   10 or more observations at teleseismic distances (> 28º)
  •   teleseismic secondary azimuthal gap < 180º
• EHB    bulletin
  •   Updated annually
  •   1960-2007
  •   ~140,000 events
  •   ~22 million phases
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EHB




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                 Ground Truth Database
• IASPEI      Reference Event List of GT0-5 events
 •   ~7,300 events
 •   ~500,000 phases
• GT5  events satisfy Bondár and McLaughlin (2009)
  selection criteria
• Used to validate
 •   3D Earth models
 •   Travel-time corrections
 •   New location algorithms
• Updated      regularly
 •   Recently added
      •   GT0 Bouncefield (UK) explosion, 2005/12/11

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Ground Truth DB




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            International Station Registry
• Jointly   maintained by the ISC and NEIC
  •   More than 15,000 stations, both active and closed
  •   Includes USArray stations
• Updated    regularly
  •   IberArray stations will be soon registered
• The   CTBTO is encouraged to register IMS stations




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                         Future Products
• Global      Earthquake Risk Model (GEM)
  •   The ISC is leading a consortium to produce a 100-year
      instrumental catalogue of large earthquakes
  •   Participants:
       •   Willie Lee, Bob Engdahl, Antonio Villaseñor, Peter Bormann,
           SISMOS, ISC and IASPEI (as advisor)
  •   Phase and amplitude readings are being entered to the
      ISC database from historical bulletins and station reports
  •   Events will be relocated with the EHB algorithm
  •   Magnitudes will be calculated according to IASPEI
      standards
       •   MS_20/MS_BB, mB/mB_BB and an Mw proxy
  •   The GEM instrumental catalogue and bulletin will be
      published at the ISC website
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