Automatic infrasound detection and location of sources in the western United States

Abstract

A catalog that characterizes sources of regional infrasound observed in the western U.S. (1 November 2010 to 31 October 2012) is produced. Data from nine University of Utah Seismograph Stations infrasonic arrays are supplemented by three additional arrays in Nevada, operated by Southern Methodist University. The detection procedure using an adaptive F-detector provides input into the Bayesian Infrasonic Source Location procedure. The catalog consists of 1510 events with indication of repeated events from many locations such as Dugway Testing Ground, Utah Test and Training Range, and New Bomb. We analyzed the relationship between seasonal variations in the event locations and wind conditions using the Ground-to-Space specifications based on publicly available operational numerical weather prediction data analysis products supplement by empirical models above 80 km. There is significant commonality between this study's bulletin and the Western United States Infrasonic Catalog published by Walker et al. (2011). A previous study utilized infrasound signals detected on the USArray Transportable Array seismic stations (2007–2008). Both results document the vast majority of events that occur during working hours, suggesting a human cause. To illustrate the utility of the event bulletin for exploring atmospheric dynamics, propagation paths of an event detected during the equinox period, when the stratospheric wind is low, were generated using a ray-tracing algorithm. We found that the observations contain stratospheric arrivals, not predicted by ray theory, possibly due to gravity waves increasing the effective jet speed.