The April 1993 eruption of Láscar in an isolated region of the northern Chilean Andes was the latest in a series of eruptions of this volcano that have been observed by satellites, and produced dacitic pumice falls and small volume pyroclastic flows. The analysis of the Landsat thermal observations over the last decade has provided us with the longest time series of observations, but a comparable data set currently under investigation also exists for Mount Etna (D.C. Pieri, 1994, pers. comm.). In the case of Láscar, the clear skies and low atmospheric water vapor content permit frequent observations of the lava dome by satellite-borne sensors ( Oppenheimer et al., 1993a).
While the above eruptions were mainly explosive in character, effusive eruptions and associated processes have also provided volcanologists with fresh insights and new challenges to hazard monitoring and prediction.