V13C-3138
High Spatio-Temporal Resolution Observations of Crater-Lake Surface Temperatures at Kawah Ijen Volcano, East Java, Indonesia
Monday, 14 December 2015
Poster Hall (Moscone South)
Jennifer L Lewicki, USGS California Water Science Center Menlo Park, Menlo Park, CA, United States, Corentin Caudron, Earth Observatory of Singapore, Singapore, Singapore, Vincent van Hinsberg, McGill University, Montreal, Canada, Philipson Bani, Laboratoire Magma et volcans, Clermont-Ferrand, France, George E Hilley, Stanford University, Geological and Environmental Sciences, Stanford, CA, United States and Peter J Kelly, US Geological Survey, Vancouver, WA, United States
Abstract:
Subaqueous volcanic eruptions comprise only 8% of all recorded eruptions in historical time, but have caused ~20% of fatalities associated with volcanic activity during this time (Mastin and Witter, 2000). Crater lakes, however, act as calorimeters, absorbing heat from intruding magma and integrating it over space and time and thus offer a unique opportunity to monitor volcanic activity. Kawah Ijen is a composite volcano located on east Java, Indonesia, whose crater hosts the largest natural hyperacidic lake (27 x 106 m3; pH <1) on Earth. As part of an international workshop on Kawah Ijen in September 2014, we tested a novel approach for mapping and monitoring variations in crater-lake apparent surface temperatures at high spatial (~30 cm) and temporal (every two minutes) resolution. We used a ground-based thermal infrared (TIR) camera from the crater rim to collect a set of visible imagery around the crater during the daytime and a time series of co-located visible and TIR imagery at one location from pre-dawn to daytime. We processed daytime visible imagery with the Structure-from-Motion photogrammetric method to create a digital elevation model onto which the time series of TIR imagery was orthorectified and georeferenced. Lake apparent surface temperatures typically ranged from ~21 to 28oC. At two locations, apparent surface temperatures were ~ 7 and 9 oC less than in-situ lake temperature measurements at 1.5 and 5 m depth, respectively. We observed large spatio-temporal variations in lake apparent surface temperatures, which were likely associated with wind-driven evaporative cooling of the lake surface. Our approach shows promise for continuous monitoring of crater-lake surface temperatures, particularly if the TIR camera is deployed as part of a permanent station with ancillary meteorological measurements to help distinguish temperature variations associated with atmospheric processes from those at depth within the lake and volcano.
