Processing of volcano infrasound using film sound audio post-production techniques to improve signal detection via array processing

Abstract

The use of infrasound for the early detection of volcanic events has been shown to be effective over large distances, and unlike visual methods, is not weather dependent. Signals recorded via an infrasound array often have a poor signal to noise ratio, as other sources of infrasound are detected and recorded along with the volcano infrasound. Array processing software does not always detect known volcanic events, in part because of the amount of noise in the infrasound signal (Taisne et al., in: Pichon, Blanc, Hauchecorne (eds) Infrasound monitoring for atmospheric studies: challenges in middle atmosphere dynamics and societal benefits. Springer International Publishing, Cham, 2019). Resampling the infrasound into the audible range and then applying the acoustic noise reduction techniques of spectral subtraction prior to array processing is shown to improve signal detection of volcanic events. The discussed technique is applicable to any infrasound signal such as infrasound from anthropogenic sources like nuclear testing.

A Pilot Experiment on Infrasonic Lahar Detection at Mount Adams, Cascades: Ambient Infrasound and Wind-Noise Characterization at a Quiescent Stratovolcano

“…To quickly and accurately locate the incipient stages of hazardous lahars from the summit area of Mount Adams with infrasound, it may be beneficial to add permanent arrays nearer to source zones. The limited detection of known mass movements to date implies that improved SNR equipment design (e.g., Pankow, 2019, 2020) and preprocessing noise reduction strategies (e.g., Williams et al, 2020) would be of use for deployments in these more exposed areas, and where source amplitudes could be relatively low. Given permitting issues, however, potentially desirous solutions like low-cost and low-power telemetered systems that reduce preparation and installation time (e.g., Schimmel et al, 2018;Ye et al, 2019), may prove challenging to implement.…”

Infrasound single-channel noise reduction: application to detection and localization of explosive volcanism in Alaska using backprojection and array processing

“…One recent development is a study by Carniel et al (2014), with the supervised approach employing statistical foreground activity detection, non-negative matrix factorisation (NMF), and Wiener filtering to reduce wind noise affecting volcanic tremor. Another recent study, by Williams et al (2020), showed how denoising infrasound traces could improve the number of volcanic eruption detections made during array processing by reducing microbaroms. This approach is based on semi-supervised adaptive spectral subtraction using non-local means.…”

Remote hydroacoustic-infrasonic detection and characterization of Anak Krakatau eruptive activity leading to, during, and following the December 2018 flank collapse and tsunami

“…e IS07 does not show continuous detections from the direction of the volcano. f The detections at IS52 are dominated by microbarom clutter (e.g., Matoza et al 2011bMatoza et al , 2013Williams et al 2020), but magnifying the plot to the time of the main eruption reveals co-eruptive signal beneath the clutter (see Fig. 4).…”