| A Global 3D P-Velocity Model of the Earth's Crust and Mantle for Improved Event Location |
Sep 2011 |
14 pages |
| Authors:
Michael L Begnaud; Sanford Ballard; Christopher J Young; James R Hipp; Marcus C Chang; Andre V Encarnacao; Charlotte A Rowe; W S Phillips; Lee K Steck; LOS ALAMOS NATIONAL LAB NM
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 | To test the hypothesis that high quality 3D Earth models will produce seismic event locations that are more accurate and more precise than currently used 1D and 2/2.5D models, we are developing a global 3D P wave velocity model of the Earth's crust and mantle using seismic tomography. In this paper, we present the most recent version of our model, SALSA3D (SAndia LoS Alamos 3D) version 1.7, and demonstrate its ... |
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| Advanced Multivariate Inversion Techniques for High Resolution 3D Geophysical Modeling |
Sep 2011 |
13 pages |
| Authors:
Monica Maceira; Haijiang Zhang; Carene Larmat; Charlotte A Rowe; Michael L Begnaud; LOS ALAMOS NATIONAL LAB NM
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| To meet the United States Government nuclear explosion monitoring requirements with high confidence, the Air Force Technical Applications Center needs new and improved capabilities for analyzing regional seismic teleseismic, and infrasound event data. Recently, the National Nuclear Security Administration has decided to move toward 3D modeling to improve knowledge of the compressional and shear velocity structure and enable us to reduce uncertainty and more accurately detect, locate, and identify small ... |
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| Seismic and Geophysical Characterization of Northern Asia |
Sep 2011 |
12 pages |
| Authors:
Kevin G Mackey; Hans E Hartse; Kazuya Fujita; Michael E Pasyanos; Michael L Begnaud; MICHIGAN STATE UNIV EAST LANSING
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| We are continuing our research effort to improve the seismic calibration of northern Asia. In conjunction with colleagues from the Geophysical Survey of Russia, we conducted a noise survey and station installation in the Amur region, south of the city of Blagoveschensk. For the noise study, four locations, each separated by about one kilometer, were surveyed. The general region was found to be rather noisy, with higher frequencies (1-20 Hz) ... |
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| Extending Regional Seismic Travel Time (RSTT) Tomography to New Regions |
Sep 2011 |
12 pages |
| Authors:
Stephen C Myers; Michael L Begnaud; Sanford Ballard; W S Phillips; Michael E Pasyanos; LAWRENCE LIVERMORE NATIONAL LAB CA
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| Lowering the global seismic detection threshold can be accomplished by introducing data recorded at regional distances (2000 km from the event) into global monitoring systems. Unfortunately, introduction of regional data degrades average epicenter accuracy compared to locations constrained solely by data recorded at greater distances. Location accuracy degrades because regional seismic travel time (RSTT) prediction error is generally greater than prediction error for waves that travel to greater distances. In ... |
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| Models for Broad Area Event Identification and Yield Estimation: Multiple Coda Types |
Sep 2011 |
9 pages |
| Authors:
W S Phillips; Hans E Hartse; George E Randall; Richard J Stead; Michael L Begnaud; Dale N Anderson; LOS ALAMOS NATIONAL LAB NM
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| Models of laterally varying attenuation and site effects of regional phases and their codas are necessary to correct regional amplitudes to reveal source effects of importance to identification and yield estimation procedures. We accomplish this using 2-D amplitude tomography, incorporating absolute spectral estimates based on precise ratio techniques and moment tensor results. The spectral constraints allow calibration to absolute levels, and can be used to validate amplitude prediction models. Constraints ... |
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| Advanced Multivariate Inversion Techniques for High Resolution 3D Geophysical Modeling |
Sep 2010 |
13 pages |
| Authors:
Monica Maceira; Haijiang; Ryan T Modrak; Charlotte A Rowe; Michael L Begnaud; LOS ALAMOS NATIONAL LAB NM
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| To meet the United States Government nuclear explosion monitoring requirements with high confidence, the Air Force Technical Applications Center needs new and improved capabilities for analyzing regional seismic teleseismic, and infrasound event data. Recently, the National Nuclear Security Administration has decided to investigate three-dimensional (3D) modeling in an effort to further improve knowledge of the compressional and shear-velocity structure as well as reduce uncertainty and more accurately detect, locate, and ... |
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| Model Development for Broad Area Event Identification and Yield Estimation |
Sep 2010 |
11 pages |
| Authors:
W S Phillips; Xiaoning Yang; Richard J Stead; Michael L Begnaud; Kevin M Mayeda; LOS ALAMOS NATIONAL LAB NM
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| Models of laterally varying attenuation and site effects of regional phases are necessary to correct regional phase and coda amplitudes to reveal source effects of importance to identification and yield estimation procedures. We accomplish this using 2-D amplitude tomography, incorporating ground truth spectral estimates based on relative coda techniques and regional moment tensor inversion. The ground truth spectra allow calibration to absolute levels and can be used to validate amplitude ... |
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| A Regional Seismic Travel Time Model for North America |
Sep 2010 |
12 pages |
| Authors:
Stephen C Myers; Michael L Begnaud; Sanford Ballard; Abelardo L Ramirez; W S Phillips; Michael E Pasyanos; Harley Benz; Raymond P Buland; LAWRENCE LIVERMORE NATIONAL LAB CA
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| Monitoring seismic events at ever-lower magnitude thresholds requires the utilization of seismic stations that are close to the event. The proliferation of seismic stations across the globe results in lower seismic detection thresholds because more stations are likely to be at regional distance to an event. However, utilization of arrival time data at regional distances often results in degraded location accuracy, because large variations in regional crust and upper-mantle structure ... |
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| Location Improvements in East Asia: Tomographic Model Analysis and Utilizing Public Data for Ground Truth Identification |
Sep 2008 |
11 pages |
| Authors:
Michael L Begnaud; Xiaoning Yang; Richard J Stead; W S Phillips; Charlotte A Rowe; Lee K Steck; LOS ALAMOS NATIONAL LAB NM
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| We continue to collect seismic catalog data from various sources and search that data for possible information to improve regional location in East Asia. Data collection and search efforts have greatly increased the availability of ground truth (GT) events and improved our ability to create detailed tomographic models for the area. We have developed several regional phase tomography models for East Asia (see Rowe et al., 2008, these Proceedings) that ... |
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| Geophysical Modeling in Eurasia: 2D Crustal P and LG Propagation; Upper- Mantle Shear Wave Propagation and Anisotropy; and 3D, Joint, Simultaneous Inversions |
Sep 2008 |
11 pages |
| Authors:
Charlotte A Rowe; Monica Maceira; Michael L Begnaud; Lee K Steck; W Scott Phillips; LOS ALAMOS NATIONAL LAB NM
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| New tomographic models have been developed to obtain improvements to travel-time predictions for a variety of crustal and upper-mantle seismic phases, and we approach the problem with both independent datasets and joint, simultaneous inversion of diverse geophysical parameters. New Pg and Lg velocity models in Eurasia improve estimates of crustal travel times across the region. Inversion of Pg and Lg travel times improves RMS by tilde 30% compared to iasp91. ... |
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| A 3D Tomographic Model of South Central Asia Based on Pn Travel Times from GT Events |
Sep 2008 |
10 pages |
| Authors:
Christopher J Young; Sanford Ballard; James R Hipp; Marcus C Chang; Glen T Barker; Michael L Begnaud; W Scott Phillips; Lee K Steck; Charlotte A Rowe; SANDIA NATIONAL LABS LIVERMORE CA
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| Increasingly, nuclear explosion monitoring is focusing on detection, location, and identification of small events recorded at regional distances. Because Earth structure is highly variable on regional scales, locating events accurately at these distances requires the use of region-specific models to provide accurate travel times. Improved results have been achieved with composites of 1D models and with approximate 3D models with simplified upper mantle structures, but both approaches introduce nonphysical boundaries ... |
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| Improving Location/Detection Methods for Monitoring Research Using Large-Scale Correction Surfaces, Cross-Correlation Techniques and Genetic Algorithms |
Sep 2007 |
11 pages |
| Authors:
Michael L Begnaud; Charlotte A Rowe; Lee K Steck; Woohan Kim; DEPARTMENT OF ENERGY GERMANTOWN MD NATIONAL NUCLEAR SECURITY ADMINISTRATION
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| The availability of seismic bulletin sources presents a problem when preparing data sets for studies. With so many choices, which catalog should be used? We have developed a method of merging data from all available seismic bulletins into a single database of non-redundant phases for each event. With this new database, additional ground truth (GT) events are readily identified due to the merging of all possible arrivals for each event. ... |
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| Geophysical Imaging of Asia and Siberia: Tomography for Seismic Velocity, Upper Mantle Gradient, Lg Attenuation, and Joint Inversion of Surface Wave Dispersion, Receiver Functions and Satellite Gravity Data |
Sep 2007 |
11 pages |
| Authors:
Charlotte A Rowe; William S Phillips; Monica Maceira; Michael L Begnaud; Lee K Steck; Xiaoning Yang; Christian L Lucero; Hans E Hartse; Richard J Stead; Kevin G Mackey; Kazuya Fujita; Charles J Ammon; LOS ALAMOS NATIONAL LAB NM
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| Our geophysical modeling efforts have focused on a variety of special studies. We continue to develop models for Eastern Russia using the Michigan State Siberia database, for which we have expanded over previous Pn velocity tomography by also inverting Lg amplitudes for a regional attenuation study, and a preliminary tomographic image of Pg travel times in Eurasia, including the Siberia region. Both Lg attenuation and Pg velocity tomographic studies illuminate ... |
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| Utilizing Results From InSAR To Develop Seismic Location Benchmarks And Implications For Seismic Source Studies |
Sep 2000 |
9 pages |
| Authors:
Michael L Begnaud; Aaron A Velasco; Lee K Steck; LOS ALAMOS NATIONAL LAB NM
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| Obtaining accurate seismic event locations is one of the most important goals for monitoring detonations of underground nuclear tests. This is a particular challenge at small magnitudes where the number of recording stations may be less than 20. Although many different procedures are being developed to improve seismic location, most procedures suffer from inadequate testing against accurate information about a seismic event. Events with well-defined attributes, such as latitude, longitude, ... |
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