Long‐term TIR imagery processing for spatiotemporal monitoring of surface thermal features in volcanic environment: A case study in the Campi Flegrei (Southern Italy)

Abstract

Different procedures were used to analyze a comprehensive time series of nighttime thermal infrared images acquired from October 2006 to June 2013 by a permanent station at Pisciarelli (Campi Flegrei, Italy). The methodologies were aimed at the detection and quantification of possible spatiotemporal changes in the ground-surface thermal features of an area affected by diffuse degassing. Long-term infrared time series images were processed without taking into account atmospheric conditions and emissivity estimations. The data obtained were compared with the trends of independent geophysical and geochemical parameters, which suggested that long-term temporal variations of the surface maximum temperatures were governed by the dynamics of the deeper hydrothermal system. Analogously, the dynamics of the shallow hydrothermal system are likely to control the short-period thermal oscillations that overlie the long-term thermal signals. The map of the yearly rates of temperature change shows temperature increases clustered in the thermal anomalous area of the infrared images, without evidence of modifications to the extension of the anomaly or of growth of new areas with significant thermal emission. This suggests that in the present state, the heat transfer is mainly due to hot gas emission through preexisting fractures and vents. Our data indicate that the comprehensive picture of the spatiotemporal evolution of the thermal features of the hydrothermal sites obtained by long-term infrared monitoring can provide useful information toward refining physical and conceptual models, as well as improving surveillance of active volcanoes.

Integrated thermal infrared imaging and structure-from-motion photogrammetry to map apparent temperature and radiant hydrothermal heat flux at Mammoth Mountain, CA, USA

“…Orthorectified and georeferenced (a) apparent surface temperature and (b) radiant hydrothermal heat flux maps of the Mammoth Mountain fumarole area. Sansivero et al, 2013;Vilardo et al, 2015;Patrick et al, 2014) is not practical and/or a study area requires numerous TIR camera looks to sufficiently map the distribution of heat emissions.…”

“…However, airborne imaging is relatively expensive, and the spatial resolution of acquired imagery from airborne and satellite platforms may be insufficient to map the spatial variability of thermal anomalies of interest. Handheld TIR cameras offer the benefits of ease of use, relatively low-cost surveys, high spatial resolution (to mm-scale) imagery, and high rate (to 60 Hz) of image acquisition (e.g., see review by Spampinato et al, 2011 and references therein;Schöpa et al, 2011;Patrick et al, 2014;Worden et al, 2014;Vilardo et al, 2015). However, the use of ground-based TIR cameras introduces the disadvantages of highly oblique and often unknown viewing orientation.…”

Diffuse carbon dioxide emissions from hidden subsurface structures at Asama volcano, Japan

“…The average and standard deviation for 100 realizations were derived for all grids. To reveal soil temperature anomalies, the difference of the temperature from a mean background temperature in each observation (hereafter δT) was used (Chiodini et al 2007;Sansivero et al 2013;Vilardo et al 2015). The mean background temperature was calculated for the measurement sites in a background region that was set in the southern flank of Kamayama cone (a region with a label BBKGD^in Fig.…”

Drone with thermal infrared camera provides high resolution georeferenced imagery of the Waikite geothermal area, New Zealand

“…Temperature calibration and georeferencing of imagery provides the potential for more accurate and reproducible surface heat flow surveys of volcanic and geothermal areas. This has many possible applications, including volcanic monitoring (Harris, 2013;Vilardo et al, 2015), environmental monitoring (Allis, 1981;Bromley and Hochstein, 2000;Óladóttir and Fridriksson, 2015), geothermal exploration (Muffler and Cataldi, 1978), and hydrothermal reservoir modelling (O'Sullivan et al, 2001;O'Sullivan et al, 2009). Our study demonstrates there are no technical barriers preventing the use of drones to produce accurate thermal and visible maps of large, inaccessible geothermal areas For non-thermal imagery, the ground resolution (4cm) and horizontal position error (~10cm) are comparable to commercially produced LiDAR and aerial imagery obtained from crewed aircraft.…”