A chronology of the 1991 to 1993 Mount Etna eruption using advanced very high resolution radiometer data: Implications for real-time thermal volcano monitoring

Between December 1991 and March 1993 a continuous effusive eruption at Mount Etna built a 7.6 km(2) lava flow field. Flows extended to within 1 km of the town of Zafferana before a successful artificial diversion was carried out higher up the volcano. During this eruption the spaceborne advanced very high resolution radiometer (AVHRR) acquired 308 images on which the activity could be detected. Since these data can be freely and directly available, such coverage potentially allows regular, real-time monitoring. Ground observations and a flow map that we produced using a SPOT image and electronic distance measurement allowed us to develop and test data extraction techniques. AVHRR radiance maps were consistent with known locations of surface activity. These documented the transition from channel to tube fed phases, the changing threat to Zafferana, and flow diversion. Quantitative analysis of the AVHRR data enabled estimation of active lava area, thermal flux, effusion rates, and total flow field volume. Our estimates for eruption rate and total flow field volume, 5.6 to 7.6 m(3)/s and 220 x 10(6) to 300 x 10(6) m(3), respectively, are in agreement with published ground-based estimates of 5.8 m(3)/s and 235 x 10(6) m(3). These correlations demonstrate the high degree of confidence that can now be placed in interpretations of AVHRR time series for eruptions where ground-based data are scanty.