This Landsat Thematic Mapper image displays the world's best exposed example of a large volcanic debris avalanche deposit. About 7,200 years ago the jolt of an earthquake on one of the faults triggered failure of Socompa's western flank, triggering an avalanche which carved out a 70 degree wedge, 12 km across, from the original 6300 m high volcano, whose present summit is seen in blue (snow in false color) at bottom right. The volume of displaced material was ten times greater than Mount St. Helens and formed a deposit which now covers about 500 square kilometers of the Atacama desert. A small proportion of the 20 cubic kilometers of material in the moving avalanche 'froze' in place to form a primary avalanche deposit (red tones; left center) and a great marginal levée (grey tones; top left margin). Most of the material came to rest transiently behind the levées, and then moved off down the northeastward facing slope, in a direction almost at right angles to the primary avalanche to form a secondary avalanche. Material which arrived at the snout of the avalanche (grey, top center) had travelled at least 40 km. (Section 13.1.1. and Fig. 13.5).

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