Infrasound monitoring in non-traditional environments

Area of Science:

• Geophysics
• Acoustics
• Civil Engineering

Background:

• Traditional infrasound monitoring focuses on distant sources using low-noise sites.
• Expanding interests include detecting low-energy urban sources, necessitating urban monitoring case studies.

Purpose of the Study:

• To demonstrate methods for overcoming challenges in urban infrasound monitoring.
• To identify the source of infrasound signals within a complex urban acoustic environment.

Main Methods:

• Deployment of two infrasound arrays (38m and 120m apertures) on Dallas building rooftops.
• Application of frequency-wavenumber analysis to determine signal backazimuths.
• Verification of identified infrasound sources using seismic measurements.

Main Results:

• 314 coherent continuous-wave infrasound packets were detected over 14 days.
• 246 detections were associated with a consistent backazimuth range.
• The Mockingbird Bridge was identified as the probable source of the infrasound signals.

Conclusions:

• The described techniques effectively overcome urban acoustic constraints for infrasound monitoring.
• This approach enables the monitoring of infrastructure conditions at local distances (0-100 km).