Use of Imperfect Calibration for Seismic Location
Efforts to more effectively monitor nuclear explosions include the calibration of travel times along specific paths. Benchmark events are used to improve travel-time prediction by (1) improving models, (2) determining travel times empirically, or (3) using a hybrid approach. Even velocity models that are determined using geophysical analogy (i.e. models determined without the direct use of calibration data) require validation with calibration events. Ideally, the locations and origin times of calibration events would be perfectly known. However, the existing set of perfectly known events is spatially limited and many of these events occurred prior to the installation of current monitoring stations, thus limiting their usefulness. There are, however, large numbers of well (but not perfectly) located events that are spatially distributed, and many of these events may be used for calibration. Identifying the utility and limitations of the spatially distributed set of imperfect calibration data is of paramount importance to the calibration effort. In order to develop guidelines for calibration utility, we examine the uncertainty and correlation of location parameters under several network configurations that are commonly used to produce calibration-grade locations. We then map these calibration uncertainties through location procedures with network configurations that are likely in monitoring situations. By examining the ramifications of depth and origin-time uncertainty, we expand on previous studies that focus strictly on epicenter accuracy. Particular attention is given to examples where calibration events are determined with teleseismic or local networks and monitoring is accomplished with a regional network.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15002081
- Report Number(s):
- UCRL-JC-138985; TRN: US200408%%64
- Resource Relation:
- Conference: 22nd Seismic Research Symposium, New Orleans, LA (US), 09/12/2000--09/15/2000; Other Information: PBD: 12 Jul 2000
- Country of Publication:
- United States
- Language:
- English
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