36. Debris Avalanche Deposit, Tata Sabaya, Bolivia
The most diagnostic feature of large volcanic debris avalanche deposits is the distinctive hummocky terrain that they produce. The photograph of the Tata Sabaya deposit illustrates this well. The volcano is located on the shores of the Salar de Coipasa, a large salt lake on the Bolivian altiplano. The debris avalanche traveled over the flat margins of the lake and extended well into the water, changing the coastline of the lake. The hummocks of the deposit stood up as small islands above lake level, and a few such islands still exist. Dessication of the lake has dried out most of the area, though, and the hummocks are now separated by salt flats, which fill all the low-lying areas. Similar areas of hummocky topography are characteristic of volcanic debris avalanches. The Galungung, Indonesia, deposit is known locally and descriptively as the “Valley of a Thousand Hills.”
Tata Sabaya is a small volcano, only 5400 meters (17,712 feet) high. The date of its collapse is not known. Postcollapse activity has largely healed the scars left by the collapse, indicated by the presence of several young lava flows.
STS-41D, August-September 1984. Picture #14-34-010.