Anomalous Acoustic Signals Recorded by the CERI Seismic Network

Lin, Tsair-Fuh; Langston, Charles A.

doi:10.1785/gssrl.77.5.572

Cited by 6 publications

(3 citation statements)

References 19 publications

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“… Lin and Langston [2006] analyzed a daytime seismic wave train recorded by the CERI network with a group velocity of about 330 m/s. They performed a similar grid search to find the parameters for a point source model.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2010

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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.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2010

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“…2 displays the beams constructed from all sensors in the array using time-delays corresponding to the calculated slowness vectors. Whilst the observation of acoustic signals on seismogram traces is not uncommon (e.g., Lin and Langston, 2006;Cates and Sturtevant, 2002), it is a useful observation that, in this case, the seismic response to the pressure changes in the incoming infrasound wavefront is so uniform over the array that standard seismic array processing can be applied to infer accurately a direction of arrival of the atmospheric wave.…”

Section: Seismic and Acoustic Observations Of Finnish Explosions At Rmentioning

confidence: 99%

Joint seismic-infrasonic processing of recordings from a repeating source of atmospheric explosions

Gibbons

Ringdal

Kværna

2007

The Journal of the Acoustical Society of America

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Abstract:A database has been established of seismic and infrasonic recordings from more than 100 well-constrained surface explosions, conducted by the Finnish military to destroy old ammunition. The recorded seismic signals are essentially identical and indicate that the variation in source location and magnitude is negligible. In contrast, the infrasonic arrivals on both seismic and infrasound sensors exhibit significant variation both with regard to the number of detected phases, phase travel times, and phase amplitudes, which would be attributable to atmospheric factors. This data set provides an excellent database for studies in sound propagation, infrasound array detection, and direction estimation.

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“…Our working hypothesis is that natural thunder can be used as a seismic source to study near‐surface velocity structure by its induced ground motions (acoustic‐to‐seismic coupling). Previous studies have shown that a variety of atmospheric disturbances such as sonic booms, meteoroid falls, thunder, and explosions recorded with a seismograph can be used to study the propagation of an acoustic wave in the atmosphere or the coupling of the acoustic wave to the ground [ Espinosa et al , 1968; Cates and Sturtevant , 2002; Brown et al , 2003; Ishihara et al , 2003; Langston , 2004; Lin and Langston , 2006]. However, most impulsive atmospheric disturbances such as sonic booms, meteoroid falls, and explosions are few and far between.…”

Section: Introductionmentioning

confidence: 99%

Thunder‐induced ground motions: 1. Observations

Lin

Langston

2009

J. Geophys. Res.

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[1] Acoustic pressure from thunder and its induced ground motions were investigated using a small array consisting of five three-component short-period surface seismometers, a three-component borehole seismometer, and five infrasound microphones. We used the array to constrain wave parameters of the incident acoustic and seismic waves. The incident slowness differences between acoustic pressure and ground motions suggest that ground reverberations were first initiated somewhat away from the array. Using slowness inferred from ground motions is preferable to obtain the seismic source parameters. We propose a source equalization procedure for acoustic/seismic deconvolution to generate the time domain transfer function, a procedure similar to that of obtaining teleseismic earthquake receiver functions. The time domain transfer function removes the incident pressure time history from the seismogram. An additional vertical-to-radial ground motion transfer function was used to identify the Rayleigh wave propagation mode of induced seismic waves complementing that found using the particle motions and amplitude variations in the borehole. The initial motions obtained by the time domain transfer functions suggest a low Poisson's ratio for the near-surface layer. The acoustic-to-seismic transfer functions show a consistent reverberation series at frequencies near 5 Hz. This gives an empirical measure of site resonance that depends on the ratio of the layer velocity to layer thickness for earthquake P and S waves. The time domain transfer function approach by transferring a spectral division into the time domain provides an alternative method for studying acoustic-to-seismic coupling.

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Anomalous Acoustic Signals Recorded by the CERI Seismic Network

Cited by 6 publications

References 19 publications

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

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

Joint seismic-infrasonic processing of recordings from a repeating source of atmospheric explosions

Thunder‐induced ground motions: 1. Observations

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