Discrimination Calibration Analysis Methods for Regional Stations

Abstract

For event discrimination, operational implementation of a regional seismic station requires three sequential calibration analyses. (1) Magnitude, distance, and amplitude corrections (MDAC) made to observe regional amplitudes are necessary so that what remains in the corrected amplitude is mostly information about the seismic source-type. Corrected amplitudes can be used in ratios to discriminate between earthquakes and explosions. Calibration of MDAC can be accomplished with empirical Bayes estimation, which naturally provides metrics to determine when adequate calibration data have been acquired, and provides statistical assurance that the errors associated with MDAC calibration are negligible in future operational discrimination analysis. (2) MDAC-corrected amplitudes can then be used in ratios to discriminate between earthquakes and explosions. However, there remain source effects such as those due to depth, focal mechanism, local material property and apparent stress variability that cannot easily be determined and applied as amplitude corrections. We have developed a mathematical model to capture these near source effects as random (unknown) giving an error partition of three sources: model inadequacy, station noise and amplitude correlation. This mathematical model is the basis for a general multi-station regional discriminant. Calibration analysis for the standard error of the discriminant includes the calculation of the variances of model inadequacy and station noise, and amplitude correlation. (3) Likelihood-based seismic event identification analysis with MDAC discriminants requires estimated source population means and covariance matrices for the discriminants from each of the possible source types used in our analysis (e.g., deep earthquake, shallow earthquake, and explosion).

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Document Details

Document Type
Technical Report
Publication Date
Sep 01, 2008
Accession Number
ADA516373

Entities

People

  • Dale N. Anderson
  • Deborah K. Fagan
  • Steven R. Taylor
  • Theresa M. Mercier

Organizations

  • Pacific Northwest National Laboratory

Tags

DTIC Thesaurus Topics

  • Abstracts
  • Air Force Research Laboratories
  • Algorithms
  • Calibration
  • Discrimination
  • Earthquakes
  • Explosions
  • Frequency
  • Ground Based
  • Identification
  • Materials
  • Mathematical Models
  • Measurement
  • Models
  • Monitoring
  • Nuclear Explosions
  • Standards

Readers

  • Computational Modeling and Simulation
  • Seismology
  • Statistical inference.