Chain reactions that enhance the impact of small trigger events
often characterize glacier disasters. Here, a comparably small
glacier lake (unseen below bottom edge of image) in the Pamir
Mountains of Tadjikistan in Central Asia burst out and triggered a
debris flow. The corresponding material spilled into the river
(flowing from right to left in image), suddenly damming it. The
tan, mushroom-shaped debris fan is clearly visible at the exit of
a gorge into the main river valley. Officials quickly cut a
channel through the far side of the fan to lower the lake level
and prevent an outburst. Note that in this image, vegetation
appears red.