Multiple-Array Detection, Association and Location of Infrasound and Seismo-Acoustic Events - Utilization of Ground Truth Information.

摘要

This work is intended to provide automated methodology for processing seismic and infrasound data from seismo-acoustic arrays and apply the methodology to regional networks for validation with ground truth information. In the initial year of the project automated techniques for detecting, associating and locating infrasound signals were developed. Recently, the location procedure has been cast into a Bayesian framework. Work this year has focused on assessment of sets of robust regional infrasound signals in order to optimize the location algorithms. Quantification of the importance of model and empirical travel times, backazimuth estimation (including errors) and signal detectability have all been undertaken and are reported. Two specific studies are reported. Infrasound from a static rocket test conducted at Promontory, Utah on11/01/2007, was observed on USArray seismographs up to a distance of 600 km. Signal durations were broadly consistent with the duration of the test, 123 s, and signal envelopes correlated with variations in thrust in some cases. The effect of adding Gaussian noise to wind profiles is investigated for the purpose of phase identification. It is shown that all observations can be predicted through the combination of simulations using different noise levels, suggesting that a probabilistic approach to phase identification is possible. These results have important implications for how atmospheric models might be utilized in source location in particular how they might be implemented into the Bayesian location framework of Modrak et al. (2010). The deterministic dependence of infrasound propagation on the season and path environment was quantified by the analysis of more than 1,000 repetitive infrasonic ground-truth events at an active, open-pit mine in Korea over 2 years.