CALCULATION OF LAVA EFFUSION RATES FROM LANDSAT TM DATA

We present a thermal model to calculate the total thermal flux for lav a flowing in tubes, on the surface, or under shallow water. Once defin ed, we use the total thermal flux to estimate effusion rates for activ e flows at Kilauea, Hawaii, on two dates. Input parameters were derive d from Landsat Thematic Mapper (TM), field and laboratory measurements . Using these parameters we obtain effusion rates of 1.76+/-0.57 and 0 .78+/-0.27 m(3) s(-1) on 23 July and 11 October 1991, respectively. Th ese rates are corroborated by field measurements of 1.36+/-0.14 and 0. 89+/-0.09 m(3)s(-1) for the same dates (Kauahikaua et al. 1996). Using weather satellite (AVHRR) data of lower spatial resolution, we obtain similar effusion rates for an additional 26 dates between the two TM- derived measurements. We assume that, although total effusion rates at the source declined over the period, the shut down of the ocean entry meant that effusion rates for the surface flows alone remained stable . Such synergetic use of remotely sensed data provides measurements th at can (a) contribute to monitoring flow-field evolution, and (b) prov ide reliable numerical data for input into rheological and thermal mod els. We look forward to being able to produce estimates for effusion r ates using data from high-spatial-resolution sensors in the earth obse rving system (EOS) era, such as Landsat 7, the hyperspectral imager, t he advanced spaceborne thermal emission spectrometer, and the advanced land imager.