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A liquefaction susceptibility map – excerpt of USGS map for the San Francisco Bay Area. Many areas of concern in this region are also densely urbanized. The other common observation is land instability – cracking and movement of the ground down slope or towards unsupported margins of rivers, streams, or the coast.
Locations of quakes magnitude 2.5 or greater in the Wabash Valley (upper right) and New Madrid (lower left) Seismic Zones. The Wabash Valley seismic zone (also known as the Wabash Valley fault system or fault zone) is a tectonic region located in the Midwestern United States, centered on the valley of the lower Wabash River, along the state line between southeastern Illinois and southwestern ...
Shaking during the earthquake caused liquefaction with instantaneous compaction and formation of many sand volcanoes. [2] [4] Maps of areas of subsidence and sand volcanoes were found to match closely with old maps of the position of former river channels. Subsidence of up to 140 cm was measured over wide areas associated with the liquefaction.
[19] [8] In the month following the earthquake, the National Oceanic and Atmospheric Administration and the USGS assembled a team to map the bathymetry of the deltas near the epicenter. This revealed multiple submarine failures on the Puyallup and Duwamish delta fronts. In other areas liquefaction, sand boils, landslides, and soil slumping ...
In 2015, the USGS unveiled the topoView website, a new way to view their entire digitized collection of over 178,000 maps from 1884 to 2006. The site is an interactive map of the United States that allows users to search or move around the map to find the USGS collection of maps for a specific area.
Seismic microzonation is defined as the process of subdividing a potential seismic or earthquake prone area into zones with respect to some geological and geophysical characteristics of the sites such as ground shaking, liquefaction susceptibility, landslide and rock fall hazard, earthquake-related flooding, so that seismic hazards at different locations within the area can correctly be ...
Soil liquefaction may cause rigid structures, like buildings and bridges, to tilt or sink into the liquefied deposits. For example, in the 1964 Alaska earthquake , soil liquefaction caused many buildings to sink into the ground, eventually collapsing upon themselves.
A special-purpose map made to show geological features. geological time scale. ... liquefaction Soil liquefaction describes the behavior of soils that, when loaded ...