Mass wasting is the movement of material downhill. In most instances mass wasting occurs by a gradual creeping of soils and rocks downhill, but during earthquakes large volumes of rock, soil, and all that is built on the area affected may suddenly collapse in a landslide. Earthquake-induced landslides occur in areas with steep slopes or cliffs, such as parts of California, Alaska, south America, Turkey, and China. one of the worst recorded earthquake-
A second photograph of damage from ground shaking and landslides in Hongkon, Sichuan Province, China, from May 12, 2008, magnitude 7.9 earthquake (T. Kusky)
Damage from ground shaking and liquefaction in Yingxin, Sichuan Province, China, causing buildings to collapse on their sides, from May 12, 2008, magnitude 7.9 earthquake (T. Kusky)
induced landslides occurred in the magnitude 7.9 Wenchuan, China, earthquake (2008) when several villages were completely buried under hundreds of feet of debris from mountains that collapsed nearby, killing thousands.
In the 9.2 magnitude Alaska earthquake (1964), landslides destroyed power plants, homes, roads, and railroad lines. Some landslides even occurred undersea and along the seashore. Large parts of Seward and Valdez sat on the top of large submarine escarpments, and during the earthquake extensive areas of these towns slid out to sea in giant submarine landslides and were submerged. Another residential area near Anchorage, Turnagain Heights, was built on top of cliffs with fantastic views of the Alaska Range and Aleutian volcanoes. When the earthquake struck, this area slid out toward the sea on a series of curving faults that connected in a slippery shale unit known as the Bootlegger shale. During the earthquake this shale unit lost all strength and became almost cohe-sionless, and the shaking of the soil and rock above it caused the entire neighborhood to slide toward the sea along the shale unit and be destroyed.
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