Infrasound sensors are deployed in a variety of spatial configurations and scales for geophysical monitoring, including networks of single sensors and networks of multisensor infrasound arrays. Infrasound signal detection strategies exploiting these data commonly make use of intersensor correlation and coherence (array processing, multichannel correlation); network-based tracking of signal features (e.g. reverse time migration); or a combination of these such as backazimuth cross-bearings for multiple arrays. Single-sensor trace-based denoising techniques offer significant potential to improve all of these various infrasound data processing strategies, but have not previously been investigated in detail. Single-sensor denoising represents a pre-processing step that could reduce the effects of ambient infrasound and wind noise in infrasound signal association and location workflows. We systematically investigate the utility of a range of single-sensor denoising methods for infrasound data processing, including noise gating, non-negative matrix factorization, and data-adaptive Wiener filtering. For the data testbed, we use the relatively dense regional infrasound network in Alaska, which records a high rate of volcanic eruptions with signals varying in power, duration, and waveform and spectral character. We primarily use data from the 2016–2017 Bogoslof volcanic eruption, which included multiple explosions, and synthetics. The Bogoslof volcanic sequence provides an opportunity to investigatemore »
We applied nonlinear thresholding and scale–time gating in the continuous wavelet transform (CWT) domain to denoise, identify and characterize seismic phases contained in gradiometer and phased array waveforms of four seismic events recorded during the 2016 Incorporated Research Institutions of Seismology Wavefields Experiment in northern Oklahoma. A dense, 80-element three component phased array was subset from the linear array deployments to examine background noise, waveform coherence and seismic wave composition for local explosion and earthquake waveforms. CWT techniques were also used to significantly improve gradiometery analyses for data recorded by the geodetic array subexperiment. We observed as much as two orders of magnitude gain in the data signal-to-noise ratio. We also saw improvement in array beam quality after denoising the seismic data. Using the signal partitioning technique, we were able to extract and identify many phases based on their positions on the scale–time plane. CWT denoising and wavefield decomposition techniques also improved gradiometry analysis results from the 112-element geodetic array (also called the gradiometer) since waves could be separated before the computation of wave attributes. The operations of removing noise and gating out signal phases improved signal coherence across array records and provided clear P wave onsets on horizontal more »
- Publication Date:
- NSF-PAR ID:
- 10387253
- Journal Name:
- Geophysical Journal International
- Volume:
- 233
- Issue:
- 1
- Page Range or eLocation-ID:
- p. 529-548
- ISSN:
- 0956-540X
- Publisher:
- Oxford University Press
- Sponsoring Org:
- National Science Foundation
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