earthquakes reflection 5- landslides/mass wasting

mass wasting

movement of material downslope, gravity acting on mass

3 types of mass wasting movement

falls, slides, flows

falls

free fall of earth material

slides

movement of material as a cohesive, coherent block along a slide plane

flows

movement of unconsolidated material with mixing

rock fall

cliffs, ice wedging, exfoliation, thermal expansion/contraction, biological activity

rock slide

large blocks of bedrock slide on tilted (planar) bedrock, rapid

soil slip

soiil/weathered earth material slides on steep tilted (planar) bedrock or cohesive sediment, fast (perceptible) or occurs over days

slump/rotational landslide

rotational sliding, cohesive blocks of rock slide on curved bed surface, can be fast, slowest type of slides, better at forecasting, create steeped terrace effect

flow flow

mixing movement/unconsolidated material, loose soil/weathered earth flows down bed beneath with air/water/bedding plane, rapid or very slow

earth flow

wet, partially cohesive soil and weathered rock, fast, debris, mud, trees, rocks

avalanche flow

snow and ice and organics, instantaneous, loose snow starts at a point and widens down slope

debris/mud flow

not cohesive fluid, mix of rocks, sand, water, mud, fast, flows like water

soil creep

rocks and soil flow down slope, slow/imperceptible, takes years, driven by freezing and thawing top layers, earthquakes can speed it up

complex slide

complex combinations of sliding and flowing, one or more different materials move, more than 1 type of sliding surface

what increases landslide susceptibility

loose earth material, steeper slopes, oversaturated sediment, tectonic activity

topographic relief

high relief = steepness, greater magnitude for driving force, mass wasting occurs more in high relief areas