Mapping Ground Temperature and Radiant Hydrothermal Heat Flux on Mammoth Mountain, CA

Abstract:

Quantifying the spatial and temporal variability of ground temperatures and hydrothermal heat fluxes in volcanic and geothermal systems is important for monitoring volcanic activity, monitoring the impacts of geothermal development, and assessing resources. We used ground based thermal infrared (TIR) imaging combined with Structure-from-Motion (SfM) photogrammetry to produce high-resolution (cm scale) DEMs over which images of ground temperature and radiant hydrothermal heat flux were draped. We apply this methodology to two hydrothermal areas (Mammoth Mountain and South Side fumaroles) on Mammoth Mountain, CA, allowing us to image the detailed topography, map the thermal features at each area and assess the spatial relationships between the two efficiently and at high resolution. Mammoth Mountain is a lava-dome complex located on the southwestern rim of Long Valley caldera, CA. Unrest at Mammoth Mountain is currently manifested by seismic swarms, ground deformation, elevated ³He/⁴He ratios in gases at the Mammoth Mountain fumarole, and large changes in diffuse magmatic CO₂ emissions from the five tree kill areas on the volcano flanks.

We augment the extensive dataset collected at this site over the previous decades by quantifying ground temperatures and hydrothermal heat fluxes at the Mammoth Mountain and South Side fumarole sites. This was accomplished using a hand-held FLIR T650sc camera that simultaneously acquires visible and TIR images of the study site. Daytime and nighttime co-located visible and TIR images were acquired over each study area, and image processing was used to orthorectify and mosaic visible and TIR images, calculate radiant hydrothermal heat fluxes, construct 3D imagery of ground surface, overlay maps of ground temperatures and heat fluxes, and establish spatial relationships between topography and heat flow.