Automated Secondary Phase Detection Using Wavelet Techniques
Small Business Information
Weston Geophysical Corp.
57 Bedford Street, Suite 102, Lexington, MA, 02420
Abstract"The primary objective of this proposed research is to develop a new detector that uses the wavelet transform for accurate, reliable and automatic detection of secondary phases such as Pg, Lg, and pPn. We propose to extend the semi-automatic waveletdetector of Tibuleac and Herrin (1999) to an automatic, multi-component detector for use on both single-component array data as well as three-component seismic data. Additional research tasks include developing a rigorous statistical framework to evaluatethe wavelet detector's performance on seismic data recorded in regions of high monitoring interest, where Pg and Lg propagation ranges from highly efficient to complete blockage. We will demonstrate that a wavelet detector offers significant improvementin secondary phase detection by comparing the method to traditional Fourier-based detectors. The final task will be to demonstrate the capability of wavelet detectors to detect and identify regional depth phases, primarily pPn, including a parallelcomparison with Fourier-based depth phase detectors. Based upon the preliminary successes demonstrated by Tibuleac and Herrin (1999, 2001), we believe that arrival times determined from automated wavelet processing will produce a higher level of accuracyin the hypocentral estimates for small-to-intermediate magnitude seismic events than has previously been achieved. A major challenge for nuclear monitoring organizations is the detection, locati
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