GLG 301 Lecture 8: 301-2017-Summary 8
Document Summary
Mass movements (see supplementary link for feb 2) What influences slope stability: slope (gravitational forces) influenced by grain size, shape, and moisture. Weight of water or mass can also destabilize: water content reduces cohesion (increased water pressure). Small amounts of water can help due to capillary cohesion (surface tension: rock/sediment type and how it is layered. How well can sediment or rock absorb water: vegetation (generally helps) reduces infiltration of water (helps) Adds weight (sort of helps can improve friction ) and roots provide cohesion (helps) (but see below) Plants (trees) with high centers of gravity (hurts) Causes of landslides: anything that reduces slope stability. Often, but not always, related to storms and floods river banks. See below: oso, washington, slump, march 22, 2014. 43 killed, similar slide occurred in 2006. Bench of former sandy alluvial fan (delta) may have become waterlogged. Note other scalloped slide edges visible in lidar images of area (http://www. usgs. gov/newsroom/images/2014_05_14/landslide,lidar.
