COOLING MECHANISMS AND AN APPROXIMATE THERMAL BUDGET FOR THE 1991-1993 MOUNT-ETNA LAVA FLOW

The 1991-1993 eruption of Mount Etna, Sicily built a 7.2 km(2) as lava flow field within the Valle del Bove. This letter provides estimates of the power losses associated with various cooling mechanisms operati ng during the development of the flow field, derived from time-series analysis of nighttime satellite remote sensing data. Unlike sensors us ed in many previous remote sensing studies of active lava, the ERS-1 A long Track Scanning Radiometer (ATSR) provides unsaturated measurement s of spectral radiance from even very hot surfaces. This allows for mo re accurate solution of the lava flow endmember thermal components. We find that radiative and conductive processes dominated, with our mode l suggesting energy losses of similar magnitude. Radiative losses peak ed about one month into the eruption, when lava flowed in open channel s. Conductive losses peaked after two months, with a marked decline ca used by a significant decrease in the horizontal spreading rate of lav a. By the end of the eruption the 235 x 10(6) m(3) of erupted lava is estimated to have lost only 28 % of its initial thermal energy. A furt her 6.5 x 10(17) J must be lost before the lava reaches ambient temper ature.