Advanced Multivariate Inversion Techniques for High Resolution 3D Geophysical Modeling

• Main Authors: Maceira, Monica, Haijiang, Modrak, Ryan T, Rowe, Charlotte A, Begnaud, Michael L
• Format: Report
• Language: English
• Subjects: EARTH CRUST; EARTH MANTLE; Geology, Geochemistry and Mineralogy; GEOPHYSICS; MULTIVARIATE INVERSION; SEISMIC DETECTION; SEISMIC WAVES; Seismology; THREE DIMENSIONAL

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 identify small (body wave magnitude mb4) seismic events. For seismically active areas, inaccurate models can be corrected using the kriging methodology; therefore, it is possible to detect, locate, and identify large events even with limited resolution models. This is not necessarily the case for smaller events, however, and it is even more of a challenge for aseismic regions. On the other hand, improving near-regional to local monitoring demands that we address the Earth's heterogeneities and 3D complexities. Motivated by the shortcomings of existing single-parameter inversion methods in accurate prediction of other geophysical parameters, this research was mainly focused during its first year on the development of advanced multivariate inversion techniques to generate a realistic, comprehensive, and high-resolution 3D model of the seismic structure of the crust and upper mantle that satisfies multiple independent geophysical datasets. During its second year, we have focused on the efficient implementation of the newly developed technique. Application to different areas around the globe with different sets of observations allows us to study sensitivities, trade-offs, and possible improvements of the methodology. We present 3D seismic velocity models of the crust and upper mantle beneath several regions, resulting from the simultaneous and joint use of seismic body-wave arrival times surface-wave dispersion measurements, and gravity data. Published in Proceedings of the 2010 Monitoring Research Review - Ground-Based Nuclear Explosion Monitoring Technologies, 21-23 September 2010, Orlando, FL. Volume I. Sponsored by the Air Force Research Laboratory (AFRL) and the National Nuclear Security Administration (NNSA). U.S. Government or Federal Rights License