2: Mass Wasting

Question 1

Geology of slope failure

Answer 1

Sliding may occur along planes of weakness in the bedrock itself
Sliding may occur in unconsolidated material (loose sediments or soil)

Question 2

Landslide Example: Yungay, Peru (1970)

Answer 2

Earthquake broke portion of glacier loose
Ice melted to produce mud slide
20,000 died from the landslide

Question 3

Vaiont Dam, Italian Alps

Answer 3

Completed in 1960, it was the world’s hghest thin-arch dam
1963 - heavy rains soaked into dipping shales
600 million tons of rock dumped into reservoir; wave overtopped dam, killed 2000 people
Reservoir behind damn now holds only debris

Question 4

Earthquake Lake Landslide, Montana

Answer 4

Triggered by M 7.3 earthquake in 1959
43 million cubic yards of steeply-inclined, foliated metamorphic rock broke loose from mountainside
Debris dammed up Madison River, creating new lake