Evolution of lava flow-fields at Mount Etna, 27-28 October 1999, observed by Landsat 7 ETM+

Landsat 7 Enhanced Thematic Mapper + (ETM+) data are presented which document the thermal characteristics of a series of lava flows emplaced at Mount Etna volcano, Sicily, during 27-28 October 1999. By examining the composition of the short-wave infrared (SWIR) signal emitted from the flow surface, we identified distinctive flow units. The first unit appears to comprise recently active lava flows with relatively cool crusts which, by virtue of the integrity of this crust as determined from the ETM+ data, we infer are stationary or barely moving. The second unit is characterized by much higher levels of SWIR radiance, consistent with a channel-fed active flow unit. Analysis of the SWIR data confirm that this is fed by a lava channel, the properties of which are consistent with vigorously active channels observed on Kilauea, Hawaii. Model predictions of the maximum length that such flows could attain compare favorably with the actual flow lengths observed in the ETM+ data, indicating that the cooler flows had indeed stopped advancing, and may have attained a cooling-limited, rather than volume-limited, maximum length. Our observations and modeling provide a physical corroboration for the supposition made by Wadge (1978) in his analysis of the shape of lava flow fields on Mount Etna, which in the cooling-limited case principal flows are active one after the other and not at the same time.