3.2 Geotechnical Relevance
The immense number of investigations into the Monte Toc slope failure make it one of the most intensively studied in history. The flood was caused by a massive landslide down Monte Toc into the Vaiont Reservoir. Prior to the 1963 landslide, as shown in Figure 2(top), the mountain slope along the southern edge of the reservoir was created by a prehistoric landslide. Signs of the slope creep were evident as early as the first filling of the reservoir. The rate of creep continued to increase rapidly until the eventual failure in October. Approximately 2.6*10^8 cubic meters slid down from the mountain slope and into the reservoir basin. It has been estimated that it took less than 45 seconds for the leading edge of the sliding mass to reach the opposite side of the gorge. Although the dam remained intact, the water continued to spill over top for several minutes. The lack of due process in analyzing the geological setting of the reservoir site appears to have lead to the catastrophic failure. As a result research of the cause of failure has prompted engineers to place more emphasis on the study of geological settings and their bearing on site construct-ability.