Ground Truth Aftershock Locations in Tibet Using Results from InSAR

Aaron A. Velasco, Michael Begnaud and Lee K. Steck
Geophysics Group (EES-11), Los Alamos National Laboratory


  • Aftershock relocations of the 1997 Nov. 8 (Mw = 7.5) Tibet earthquake poorly located with teleseismic data and standard techniques.
  • Mainshock and secondary surface rupture (ground truth) identified from InSAR (Peltzer et al., 1999).
  • No known seismic event associated with secondary rupture; goal to find event and use as ground truth.
  • Largest aftershock is only mb = 5.1; must rely on regional data.
  • Will add significant amount of regional data, test relocation approach, and obtain higher resolution aftershock relocations.


    Seismicity, faults, and topography of the region where the Nov. 8, 1997 Tibet earthquake occurred. The USGS events from Jan. 1973 to prior to mainshock (white circles) are plotted along with PDE mainshock and aftershock locations (shaded circles). The long period surface wave solution from Velasco et al. (1999) gives a strike-slip mechanism. The earthquake occurred west of the mapped trace of the Kun Lun fault and is 750 km south of the Lop Nor Nuclear Test Site. Shaded triangles are digital stations within the region.

    Click 'InSAR Results' below to continue.

    Introduction | InSAR Results | Previous Location Results | Method and Data | Results | Summary and Future Work