CMG: Improved Seismic Inference via Better Spectrum Estimation

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

CMG RESEARCH: Improved Seismic Inference via Better SpectrumEstimation Intellectual Merits: Much of the inference in seismology, from normal--mode studies to analysis of faulting mechanisms, depends on having reliable estimates of spectra and, possibly more important, reliable estimates of their uncertainties. The collaborative effort between mathematics and geophysics in this proposal is being driven by the development and deployment of high dynamic range broadband sensors networks in the field of seismology that require the development and implementation of sophisticated data analysis tools to create a better understanding of the earthquake source and Earth structure. The spectra of the transient elastic body waves (P and S waves) provide fundamental information and constraints on earthquake source properties and physics. Currently the state-of-the- art for the study of the physics of earthquakes is the estimation of source parameters, usually estimated from the spectra of the transient seismic waves. Spectral analysis has recently undergone a revolution with the development of sophisticated techniques in which the data are multiplied in turn by a set of tapers that are designed to maximize resolution and minimize bias. In addition to minimizing the bias while maintaining a given resolution, the multi-taper approach allows an estimate of the statistical significance of features in the power spectrum. Developing quadratic inverse theory that utilizes not only the spectral estimators, but the time and frequency derivatives of the spectrum, to generate a much higher resolution spectra. This project will extend this theory from a univariate theory to generalized multivariate theory. While the applications discussed here are seismic, it is clear that there are other geophysical, scientific, and engineering applications that will benefit from the proposed studies. Obvious candidates are climate studies (both paleo and modern), and space physics. Broader Impacts: Advancing discovery and understanding while promoting teaching, training, and learning. Broaden participation of underrepresented groups by participation of minority students and by presenting project related web pages in English and Spanish. Broad dissemination of results will be accomplished through conference presentations, journal articles, and web presentations.