Damaged homes at the Turnagain Heights landslide area in Anchorage.
A subsidence trough (or graben) formed at the head of the L Street landslide in Anchorage during the earthquake. The slide block, which is virtually unbroken ground to the left of the graben, moved to the left. The subsidence trough sank 7 to 10 feet in response to 11 feet of horizontal movement of the slide block. A number of houses were undercut or tilted by subsidence of the graben. Note also the collapsed Four Seasons Apartment Building and the undamaged three-story reinforced concrete frame building behind it, which are on the stable block beyond the graben.
One of the scarps bounding the graben of the L Street landslide in Anchorage. The house was undercut by subsidence of the graben.
Scarp at the subsidence trough or graben of the Fourth Avenue landslide, downtown Anchorage. Before the earthquake, the side walk in front of the stores on the right, which are in the graben, was at the level of the street on the left, which was not involved in the subsidence. The graben subsided 11 feet in response to 14 feet of horizontal movement of the slide block during the earthquake.
The marquee of the Denali Theater, which was in the graben of the Fourth Avenue landslide in Anchorage, subsided until it came to rest on the sidewalk in front of the theater, which was on ground not involved in the landslide.
Subsidence of the graben at the head of the Government Hill landslide in Anchorage tore apart an elementary school and converted the schoolyard into a jumble of fissures, scarps, and tilted and subsided blocks of broken ground. The flat and relatively unbroken large slide block in the foreground moved away from the school horizontally and as a single mass, creating a void into which the graben block spread and subsided.