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Correlation.md

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Correlation Format Specification

Description

Correlation is a format designed to encode the basic information of a seismic cross-correlation. Correlation uses the JSON standard.

Usage

Correlation is intended for use in seismic data messaging between seismic applications and organizations.

Output

    {
      "Type"      : "Correlation",
      "ID"        : String,
      "Site"      :
      {
         "Station"  : String,
         "Channel"  : String,
         "Network"  : String,
         "Location" : String
      },
      "Source"      :
      {
         "AgencyID" : String,
         "Author"   : String
      },
      "Phase"       : String,
      "Time"        : ISO8601,
      "Correlation" : Number,
      "Hypocenter"  :
      {
          "Latitude"        : Number,
          "Longitude"       : Number,
          "Depth"           : Number,
          "Time"            : ISO8601,
          "LatitudeError"   : Number,
          "LongitudeError"  : Number,
          "DepthError"      : Number,
          "TimeError"       : Number
      },
      "EventType" :
      {
          "Type"      : String,
          "Certainty" : String
      }
      "Magnitude"   : Number,
      "SNR"         : Number,
      "ZScore"      : Number,
      "DetectionThreshold" : Number,
      "ThresholdType"      : String,
      "AssociationInfo"    :
      {
         "Phase"    : String,
         "Distance" : Number,
         "Azimuth"  : Number,
         "Residual" : Number,
         "Sigma"    : Number
      }
    }

Glossary

Required Values:

These are the values required to define a correlation.

  • Type - A string that identifies this message as a correlation.
  • ID - A string containing an unique identifier for this correlation.
  • Site - An object containing the station the correlation was made at, see Site.
  • Source - An object containing the source of the correlation, see Source.
  • Phase - A string that identifies the seismic phase that was correlated.
  • Time - A string containing the UTC arrival time of the phase that was correlated, in the ISO8601 format YYYY-MM-DDTHH:MM:SS.SSSZ.
  • Correlation - A decimal number containing the correlation value of the detection.
  • Hypocenter - An object containing the hypocenter of the correlation, see Hypocenter.

Optional Values:

The following are supplementary values that may or may not be provided by various correlation algorithms.

  • EventType - An object containing the event type of the correlation, see EventType.
  • Magnitude - A decimal number identifying the relative magnitude of the correlation.
  • SNR - A decimal number identifying Signal to Noise Ratio at the time of the correlation, capped at 1E9.
  • ZScore - A decimal number identifying Z Score at the time of the correlation.
  • DetectionThreshold - A decimal number identifying detection threshold that was used to declare this correlation.
  • ThresholdType - A string containing the type of detection threshold that was used.
  • AssociationInfo - An object containing the association information if this correlation is used as data in a Detection, see Associated.