ABSTRACTThe evolution of the Grande del Nevado Glacier surge was documented through analysis of Landsat data, using image and computer-compatible tape formats, for 22 different dates between 1976 and 1986. Through time-lapse analysis of the sequential satellite images, it was determined that the glacier had a surge or rapid advance in 1984. The glacier front was in progress sometime between 16 February 1984 and 4 April 1984. Following an advance of 2.7 km, it dammed the Río Plomo in November 1984, creating a lake which, by January 1985, was 2.8 km long and 1.1 km wide. Fortunately, in March 1985, the lake began slowly draining through a natural subglacial tunnel, and continued outflowing until the end of this month, when the lake was no longer observable on satellite images.