Global Ground Truth Data Set with Waveform and Arrival Data

Abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) 30 SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)Air Force Research Laboratory 29 Randolph Rd. Hanscom AFB, MA 01731-3010 SPONSOR/MONITOR'S ACRONYM(S)AFRL/RVBYE SPONSOR/MONITOR'S REPORT NUMBER(S)AFRL-RV-HA-TR-2007-1101 DISTRIBUTION / AVAILABILITY STATEMENTApproved for Public Release; Distribution Unlimited. SUPPLEMENTARY NOTES ABSTRACTWe present the final results of our three-year research project to produce a high-confidence global GT5 data set. During the course of this project we have developed, tested, and validated the hybrid HDC-RCA (Hypocentroidal Decomposition and Reciprocal Cluster Analysis) methodology to produce new GT5 or better event locations from event clusters. The HDC algorithm uses regional and teleseismic data to estimate precise relative event locations with respect to the cluster centroid. The RCA algorithm uses local data to precisely locate the cluster centroid. We have demonstrated that the HDC-RCA multiple event location methodology is able to produce high-confidence GT5 (epicenter and depth) or better event locations using only a few local stations, without reliance on independent GT information. A posteriori assessment procedures and a priori applicability criteria have been developed and tested to assure the quality and high-confidence of the resulting GT5 events. We have developed a novel, adaptive approach to waveform cross-correlation for improved differential arrival time measurements. The method finds the optimal time-bandwidth product to perform waveform cross-correlation, thus maximizing the similarity between waveforms for a wide range of seismic phases. Correlations are accepted or rejected based on their significance level derived from the estimated time-bandwidth product. We have further developed an error model to estimate the a priori uncertainties in differential time measurements in order to facilitate their inclusion with bulletin arrival time picks in the HDC algorithm. We demonstrated differential times contribute to significant improvements in resolving the relative event locations in the HDC analysis and validated the cross-correlatio...

Multiscale Modeling and Process Optimization for Engineered Microstructural Complexity

“…By relocating a large number of GT events (GT0-2 nuclear explosions, and GT5 earthquakes produced by Reciprocal Cluster Analysis (Bondár et al, 2007(Bondár et al, , 2008 we show that ignoring the correlated error structure leads to rapidly deteriorating error ellipse coverage and location bias with increasingly correlated networks. Calibrated travel-times are responsible for the bulk of location improvements, but they do little to improve error ellipse coverage.…”

“…Figure 4 shows the GT event clusters we use throughout this study. The data set consists of GT0-2 nuclear explosions from the SAIC Nuclear Explosion Database (www.rdss.info, Bahavar et al, 2007), and GT5 earthquakes produced by the hybrid Hypocentroidal Decomposition and Reciprocal Cluster Analysis (HDC-RCA, Bondár et al, 2007Bondár et al, , 2008. We use arrival times and phase names from the groomed ISC bulletin (EHB, Engdahl et al, 1998), which for the earthquake clusters were subjected to further quality control during the HDC-RCA processing.…”

“…To establish SNR-dependent models of delay and variance, we used first-arriving P from 12 GT5 earthquake clusters (Bondár et al, 2007(Bondár et al, , 2008 with SNR ≥ 3 reported in the PIDC/IDC REB. We calculated all possible double-differences (DD) in each cluster and selected two subsets for each cluster.…”

“…The area of the ellipse encompassing the point cloud at the 90% confidence level decreases for all clusters when SSSCs are applied, and further decreases for 5 out 7 seven clusters when both SSSCs and mb-delay corrections are applied. The mb-based error models were also tested with relocation experiments using over 2,000 globally distributed GT5 events (primarily earthquakes) produced by Bondár et al, (2007Bondár et al, ( , 2008. We used both regional Pn and teleseismic P arrivals to relocate the GT5 earthquakes.…”

“…Hence, any validation tests of SNR-dependent delay and variance models, derived from direct, sta/lta measures of SNR, must rely on events with station readings reported in the REB. This limited data availability restricted the location test to 493 GT5 earthquakes (Bondár et al, 2007) with 1,440 Pn and 5,057 P arrivals reported in the PIDC/IDC REB. These events are overwhelmingly dominated by teleseismic P for which the delay correction is quite modest.…”