Integrated Verification Experiment data collected as part of the Los Alamos National Laboratory's Source Region Program. Appendix E: Local and near-regional seismic data for IVEs.

摘要

Our goal was to obtain a better understanding of the effects of near-source phenomenology on far-field signals used for monitoring the testing limits of the Threshold Test Ban Treaty. Specifically, we tried to determine if regional phases, with or without corrections for working point media or spallation effects, provide yield estimates with acceptable uncertainties. When acquiring regional seismic data, careful selection of hard-rock sites was paramount to reducing the ground-motion amplitude scatter typical of network data sets. In spite of this cautious approach to siting stations, the scatter of the observed amplitudes was unacceptably large, and so we tried measurements of the near-total-wave trains to bring the range of estimates for any given explosion down to more acceptable levels. Most of our field deployments for recording seismic signals from NTS events at local and near-regional distances were toward the east along a profile that passes by the LANL intrasound array site at St. George, Utah, and continues by the Lawrence livermore National Laboratory seismic station at Kanab, Utah. The Sandia National Laboratories seismic station at Leeds, Utah is between St. George and Kanab. Typically, four to six stations were set up to record intermediate-period data, and four to eight stations were set up to record the high-frequency data. Intermediate-period seismic stations, high-frequency seismic stations, and intrasound arrays of stations were collocated whenever possible to maximize the data acquired with the manpower and equipment resources available. We used two types of instrumentation for recording the regional seismic waves: high-frequency and intermediate-period systems. The high-frequency system records acceleration to a corner frequency at approximately 25 Hz and records velocity at higher frequencies. The intermediate-period system records velocity at frequencies above the seismometer period of 5 s.