Abstract: Slope-Stability Problems of Circum-Pacific Region as Related to Mineral and Energy Resources

D. J. Varnes

The varied geologic, topographic, and atmospheric conditions in the Circum-Pacific area have led to the development of all the types of movements to which both natural and constructed slopes are subject. These movements have resulted in significant loss of life and property and, many times, have affected the planning or operation of works related to the development of mineral and energy resources. Although many slope failures have been initiated by active seismic and volcanic processes, which are almost ubiquitous in the region, many are equally the result of local high relief, weak rocks and soil, rapid weathering, heavy rainfall, or the works of man.

As slopes in open-pit mines are extended deeper to extract metallic ores and coal, the problems of slope stability increase rapidly. Failures of pit slopes in Australia, the Philippines, Canada, the United States, and Chile, and of waste piles and tailings dams emphasize the ever-increasing need for rational analysis and design of manmade slopes to assure the safety and economy of resource development.

Landslides within a producing oil field in California have been a problem for 50 years. The threat of subaqueous slides in areas of potential petroleum extraction in many parts of the continental shelves and slopes of the Circum-Pacific region is a serious concern, and the possibility must be thoroughly evaluated. Breaks in the trans-Ecuador oil pipeline caused by landslides halted production from the Oriente fields for about a month in 1976. Destruction of petroleum handling and storage facilities at ports in Alaska was caused chiefly by underwater-slope failures and the resulting waves that were triggered by the earthquake of March 27, 1964.

Much of the development of hydroelectric energy in New Zealand, Australia, Japan, Canada, the United States, Colombia, and Peru has depended on solving slope-stability problems at the sites of dams, tunnels, powerhouses, penstocks, and reservoirs.

AAPG Search and Discovery Article #90962©1978 AAPG 2nd Circum-Pacific Energy and Minerals Resource Conference, Honolulu, Hawaii