Val Pola landslide

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Pizzo Coppetto - Alta Valtellina (Sondrio)
Adda River location

The Val Pola landslide (Val Pola rock avalanche ) happened in Valtellina, Lombardy, Northern Italian Alps, on July 28, 1987 and resulted in the Valtellina disaster (destruction of villages, road closure, flooding threat) with the total cost of 400 million euros. [1][2] [3]

In June-July 1987, Valtellina witnessed and exceptionally high rainfall accompanied with rapid glacier melting due to relatively high altitude of the 0 degree isotherm. As a result the Val Pola Creek significantly eroded its valley flanks, including the area of debris accumulation of post-glacial landslides.[3] This resulted in a fracture which detached an estimated volume 35-45 million cubic metres of old debris from the Northern slope of the Mount Zandila (Eastern side of Pizzo Coppetto[4]) first detected on July 25. On July 26 evacuations of local villages started. The fracture eventually produced a rapid rock avalanche with subsequent shallow landslides of the Val Pola sides and a debris flow along the Val Pola thalweg.[5] The flow entrained estimated 5-8 million cubic meters of debris. The created alluvial fan dammed the Adda River and created a lake. The mass run about 1.5 km downstream and generated an upstream mud wave 35m high which traveled about 2.7 km. [3]

Twenty-two people were killed by the main landslide, which created a huge wave in the temporary lake caused by a previous, smaller landslide.[5]

The landslide resulted in 35 m deepening of the Val Pola canyon.[5]

References[edit]

  1. ^ Costa, J. E.: Nature, mechanics, and mitigation of the Val Pola landslide, Valtellina, Italy, 1987–1988. Zeitschrift fur Geomorphologie 35, 15–38, 1991.
  2. ^ Natural Disasters (1993) ISBN 1-85728-094-6, p. 364
  3. ^ a b c "Numerical modelling of large landslides stability and runout", Natural Hazards and Earth System Sciences (2003) 3: 523–538
  4. ^ "Vatellina 2007", a civil protection national exercise
  5. ^ a b c "Val Pola Rock avalanche of July 28, 1987"