Source location of the 19 February 2008 Oregon bolide using seismic networks and infrasound arrays

Abstract

On 19 February 2008 a bolide traveled across the sky along a southern trajectory ending in a terminal burst above Oregon. The event was well recorded by the USArray, other seismic networks, four infrasound arrays, and several video cameras. We compare the results of locating the burst using these different sensor networks. Specifically, we reverse time migrate acoustic‐to‐seismic coupled signals recorded by the USArray out to 800 km range to image the source in 2‐D space and time. We also apply a grid search over source altitude and time, minimizing the misfit between observed and predicted arrival times using 3‐D ray tracing with a high‐resolution atmospheric velocity model. Our seismic and video results suggest a point source rather than a line source associated with a hypersonic trajectory. We compare the seismic source locations to those obtained by using different combinations of observed infrasound array signal back azimuths and arrival times. We find that all locations are consistent. However, the seismic location is more accurate than the infrasound locations due to the larger number of seismic sensors, a more favorable seismic source‐receiver geometry, and shorter ranges to the seismometers. For the infrasound array locations, correcting for the wind improved the accuracy, but implementing arrival times while increasing the precision reduced the accuracy presumably due to limitations of the source location method and/or atmospheric velocity model. We show that despite known complexities associated with acoustic‐to‐seismic coupling, aboveground infrasound sources can be located with dense seismic networks with remarkably high accuracy and precision.