Calibration of International Monitoring System (IMS) Stations in Central and Eastern Asia for Improved Seismic Event Location

Murphy, John; Rodi, William; Johnson, Michelle L.; Sultanov, D. D.; Bennett, Theron J.; Toksöz, M. Nafi; Ovtchinnikov, V. M.; Barker, B. W.; Reiter, Delaine T.; Rosca, Anca; Shchukin, Y.

doi:10.1785/0120040087

Cited by 29 publications

(33 citation statements)

References 10 publications

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“…However, location er rors are being reduced dramatically with the addition of more seismic stations, correlation analysis, InSAR, and 3D models. 17 …”

Section: Locationmentioning

confidence: 99%

Progress in CTBT Monitoring Since its 1999 Senate Defeat

Hafemeister

2007

Science & Global Security

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“…However, location er rors are being reduced dramatically with the addition of more seismic stations, correlation analysis, InSAR, and 3D models. 17 …”

Section: Locationmentioning

confidence: 99%

Progress in CTBT Monitoring Since its 1999 Senate Defeat

Hafemeister

2007

Science & Global Security

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“…Herrin and Taggart (1968) Although in the past few years several non-linear hypocenter location methods were developed to account for non-linearity and non-Gaussian error distributions (e.g. Billings, 1994;Billings et al, 1994;Sambridge and Gallagher, 1993;Sambridge and Kennett, 2001;Rodi et al, 2002), most routinely used location algorithms (including the one we used in this study) assume Gaussian, independent errors. One of our major motivations for developing the constrained bootstrapping technique was to minimize the effect of correlated errors on the validation test.…”

Section: Correlated Errors Versus 90% Coveragementioning

confidence: 99%

“…Recently, tomographic inversion was applied to derive high-resolution 3D models in Eastern and Central Asia (Murphy et al, 2002). GT data were kriged to develop empirical travel-times for events in the Caucasus Mountains (Myers and Shultz, 2000a).…”

Section: Introductionmentioning

confidence: 99%

Validation of Regional and Teleseismic Travel-Time Models by Relocating Ground-Truth Events

Yang¹,

Bondár²,

Bhattacharyya³

et al. 2004

Bulletin of the Seismological Society of America

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SUMMARYRecently developed three-dimensional global seismic-velocity models have demonstrated location improvements through independent regional and teleseismic travel-time calibration. Concurrently, a large set of high quality ground truth (GT) events with location accuracies 10 km or better (GT0-GT10) has been collected for Europe, the Medite rranean, North Africa, the Middle East, and Western Eurasia. In this study, we validate event location improvements using this new data set by applying the regional and teleseismic modelbased travel-time calibrations (independently and jointly) to demons trate that significant improvements can be achieved using 3D global models for locating small events with sparse network data. Besides relocating events using all station arrivals, a subset of the GT events was also relocated using controlled station geom etries generated from a "constrained bootstrapping" technique. The advantages of this approach include: (1) generating simulated sparse networks (Simulated Sparse Network Bulletin or SSNB), (2) increasing the statistical power of the tests, (3) reducing the effect of correlated errors to ensure valid 90% error ellipse coverage statistics, and (4) measuring location bias due to un-modeled three-dim ensional (3D) Earth structures.With respect to the GT events, we compared event relocations, with and without t raveltime calibrations, considering statistics of mislocation, error ellipse area, 90% coverage, origin time bias, origin time errors, and misfit. Relocations of more than 1000 GT0-GT10 reference events show significant reductions in location bias and uncertainty. Pn and/or P calibration reduces mislocation for between 60% and 70% of the events. Joint regional Pn and teleseismic P travel-time calibration provided the largest location improvements, and approximately achieved GT5 accuracy levels. Due to correlated 3 errors, calibrated event locations using large numbers of stations have deficient 90% error ellipse coverage. However, the coverages derived from the model errors are appropriate for sparse regional and teleseismic networks. This validation effort demonstrates that the global model-based travel-time calibrations of Pn and teleseismic P travel-time reduce both location bias and uncertainty over wide areas.

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“…These path effects are also being referred to as source-specific station corrections or SSSCs (e.g. Morozov et al, 2005;Murphy et al, 2005;Ritzwoller et al, 2003;Yang et al, 2001Yang et al, , 2004.…”

Section: B) A)mentioning

confidence: 99%

“…Recognizing the problem of location bias due to inadequate velocity models, most recent location calibration efforts focused on developing better travel-time predictions, either model based or empirical (e.g. Flanagan et al, 2007;Morozov et al, 2005;Murphy et al, 2005;Myers and Schultz, 2000;Reiter et al, 2005;Ritzwoller et al, 2003;Yang et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Multiscale Modeling and Process Optimization for Engineered Microstructural Complexity

Haile¹,

Ortiz²,

Ravichandran³

et al. 2007

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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) PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Science Applications International Corporation 10260 Campus Drive San Diego, CA 92121 PERFORMING ORGANIZATION REPORT NUMBER 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-2008-1074 DISTRIBUTION / AVAILABILITY STATEMENTApproved for Public Release; Distribution Unlimited. SUPPLEMENTARY NOTES ABSTRACTThe objective of this project was to develop methodologies that improve location uncertainties in the presence of correlated, systematic model errors and non-Gaussian measurement errors. We have developed a methodology based on copula theory to obtain robust estimates of variogram models for travel-time error. Using this methodology, we produced generic, transportable variogram models for regional Pn and teleseismic P phases. These models are employed to estimate the network covariance matrix that describes the spatial correlation structure of travel-time predictions errors. We have developed and validated models of measurement errors that map phase picking delay and variance as a function of SNR, as well as a function of epicentral distance and body wave magnitude considered as a surrogate for SNR. The phase pick delays are implemented as travel-time corrections, while the measurement error variances add to the diagonal of the network covariance matrix to obtain the full, non-diagonal data covariance matrix. Our representation of model and measurement errors assumes that the bulk of 3D velocity heterogeneities in the Earth are accounted for by calibrated travel-time predictions. We have developed a linearized iterative location algorithm that makes use of the full data covariance matrix, hence accounts for the correlated model error structure. By relocating a large number of GT events (GT0-2 nuclear explosions, and GT5 earthquakes produced by Reciprocal Cluster Analysis we show that ignoring the correlated error structure leads to rapidly deteriorating error ellipse coverage and locat...

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Calibration of International Monitoring System (IMS) Stations in Central and Eastern Asia for Improved Seismic Event Location

Cited by 29 publications

References 10 publications

Progress in CTBT Monitoring Since its 1999 Senate Defeat

Progress in CTBT Monitoring Since its 1999 Senate Defeat

Validation of Regional and Teleseismic Travel-Time Models by Relocating Ground-Truth Events

Multiscale Modeling and Process Optimization for Engineered Microstructural Complexity

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