Tracking a Rangeland Fire With Infrasound Arrays

Abstract

We present the first infrasound analyses of a rangeland fire and demonstrate infrasound's potential in monitoring wildland fires. We recorded a prescribed fire in sagebrush steppe in cool, moist conditions, using eight infrasound arrays of diverse size (3–44 sensors, 10–200 m width) and distance (0–20 km), including four arrays inside the burn area. Infrasound arrays within 2 km of fires detected coherent infrasound between 1 and 10 Hz, both during active ignitions and also while existing fires continued burning during breaks in ignitions. During periods of active ignitions, the direction of arrival estimated by a 44‐sensor array closely tracked the actual locations where the helicopter was igniting vegetation. Despite being farther from the fire than four smaller arrays, the 44‐sensor array performed best at identifying coherent infrasound and yielding consistent directions of arrival. Our results show infrasound's potential for tracking low‐intensity wildland fires in research or hazard monitoring.

Plain Language Summary:

Wildland fires are hazardous and complex events that are inhospitable to ground‐based measurement. Current aerial and satellite measurement platforms rely on line‐of‐sight techniques that are sensitive to the presence of smoke and the point of observation. By contrast, sound transmission and detection are not sensitive to the presence of smoke and can monitor sound sources in near real‐time. In this study, we use infrasound (pressure waves in air) to monitor the progression of a rangeland fire. This new fire monitoring approach has the ability to capture a wider range of fire sizes, is not dependent upon line‐of‐sight techniques, and does not interfere with wildland fire suppression operations. Infrasound is already in wide use for monitoring other hazards, but its use in wildland fire monitoring is new. In this low‐intensity rangeland fire, we detected infrasound up to about 2 km from the fires that produced it. Clusters of sensors, called infrasound arrays, were able to identify the direction to the fire and track its progress as the fires moved. This critical information, detectable for even mild fires, has the potential to aid in wildland fire monitoring and provide information across a wide range of time and space scales.

Citation

Anderson, Jacob F.; Hunt, Madeline A.; Johnson, Jeffrey B.; Yedinak, Kara M. 2026. Tracking a Rangeland Fire With Infrasound Arrays. Geophysical Research Letters. 53(13): e2026gl122492. 10 p. https://doi.org/10.1029/2026gl122492.