EART 2 Lecture Notes - Lecture 23: Frank Slide, Madison River, Ground Vibrations
Document Summary
When driving forces exceed resisting forces, slopes fail. Driving forces: weight acting parallel to the bed. Resisting force: friction (weight acting perpendicular to the bed), cohesion (clay, roots) Slopes - the larger the angle, the larger the component of driving force will be relative to the resisting force. Types of materials-the coefficient of friction differs for different materials. Biology (roots give cohesion, ground cover slows penetration of water) Water: in soilrock pores and cracks it can support weight of the rocks - reduce friction on slipping surface. Solifluction in tundra = creep associated with freeze/thaw. Rocky environments, no soil development or plant stabilization. Fast falls, but tend to be limited in size. Frank slide, canada 1903, 90 million ton rock mass slid, 70 dead. These are jumbled deposits in natural drainage system. Gros ventre debris slide, wyoming, 1925, dam failed, lake dropped 15 m. Madison river slide dam 1959; dam is 60-120 m high, 28 died.
