Utilizing Results from InSAR to Develop Seismic Location Benchmarks and Implications for Seismic Source Studies



Data and Velocity Models

  • Few events within the time period of the InSAR analysis are candidates for the secondary rupture.
  • All of the events are scattered and biased south of the rupture, with a 20-km bias for the mainshock location (Steck et al., 2000).
  • A Joint Hypocenter Determination (JHD) approach (Dewey, 1983) applied to the aftershocks using global picks was not able to identify the secondary event (Velasco et al., 2000).
  • Use the global catalog as a guide to obtain waveform data from the IRIS database for a set of digital seismic stations within 30 degrees of the mainshock.
  • Individually pick regional travel-time data for all of the aftershocks of this Tibetan earthquake, pick all regional phases than can be identified, and explore the use of S-phases for location.
    Merge regional picks with the global catalog picks from the Reviewed Event
  • Bulletin (REB) developed by the prototype International Data Center (pIDC) and the USGS Earthquake Data Reports (EDR).
  • For consistency and for handling the uncertainty of the travel-time picks, assign measurement errors for regional P- and S-waves to be 1.0 s and 2.0 s, respectively. For the global catalog, assign the measurement errors for P- and S-waves to be 2.0 s and 3.0 s, respectively.
  • Use regional models and modeling errors from previous studies (Jih, 1998; Li and Mooney, 1998; Steck et al., 2000). Calculate travel times for S phases for these same 1-D velocity models, and add a Tibetan model (Jih, 1998).
  • Employ 2-D travel-time corrections (or propagation path corrections - PPCs) based on residuals for regional 1-D velocity models that developed using a kriging interpolation algorithm (Schultz et al., 1998; Steck et al., 2000). Removes the 20-km location bias observed for the Tibet mainshock event (Steck et al., 2000).

  • Introduction | Surface Rupture | Data and Velocity Models | Synthetic Tests and Relocation Procedure | Search for Secondary Rupture Event | Relocation Results | Waveforms for Candidate Events | Relocation of Candidate Events | Conclusions and Recommendations | References