TEMPERATURE OF AN ACTIVE LAVA CHANNEL FROM SPECTRAL MEASUREMENTS, KILAUEA VOLCANO, HAWAII

A narrow band spectroradiometer was used to determine the characterist ic temperatures of a very active channeled lava flow for the phase 50 eruption of Pu'u 'O'o on the East Rift Zone of Kilauea Volcano, Hawaii . During the twilight of 19 February 1992, 14 spectra of this activity were acquired over a 51 minute interval [18.29 to 19.20 Hawaiian Stan dard Time (HST)], from which the thermal distribution of energy of two 18 m2 areas, one near the center and one near the margin of the flow, may be investigated. A two-component thermal mixing model applied to the data taken of the center of the channel gave, in the most powerful instance (1.8 x 10(5) W/m2), a crust temperature of 940-degrees-C, a hot component temperature of 1120-degrees-C and a hot radiating area o f 60% of the total area. A simultaneous spectrum acquired near the cha nneled flow margin yielded a crust temperature of 586-degrees-C and a hot area of only 1.2% of the total area radiating at 1130-degrees-C. A verage radiant flux densities recorded for the center of the lava chan nel (1.3 x 10(5) W/m2 average) are much greater than previous measurem ents of lava lakes (4.9 x 10(3) W/m2) or recently emplaced lava flows (maximum of 7.2 x 10(4) W/m2). The energetic nature of this eruption i s shown by satellite measurements made at 02.33 HST on 22 February 199 2 by the Advanced Very High Resolution Radiometer in Band 2 (0.72-1.10 mum). These show the utility of using existing satellites with modera te resolution (1 km x 1 km pixels) and high temporal coverage (eight o verpasses each day for Hawaii) as potential thermal alarms for rapidly assessing the hazard potential of large volcanic eruptions.