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Land subsidence is a global issue and has different causes. Some are natural, like earthquakes , and some are caused by humans. In the United States, land subsidence from over pumping has affected 45 states and accounts for changes in over 17,000 square miles of land which is an area almost 10 times the size of Glacier National Park in Montana ...
Groundwater-related subsidence is the subsidence (or the sinking) of land resulting from unsustainable groundwater extraction.It is a growing problem in the developing world as cities increase in population and water use, without adequate pumping regulation and enforcement.
The USGS uses the data from borehole extensometers provided by the DWR, and also utilizes information from piezometers to track changes in groundwater. [11] As of 2018, the USGS has been using large hexagonal-shaped sensor rigged to a helicopter to measure groundwater salinity and map underground aquifers in the San Joaquin Valley.
Subsidence frequently causes major problems in karst terrains, where dissolution of limestone by fluid flow in the subsurface creates voids (i.e., caves).If the roof of a void becomes too weak, it can collapse and the overlying rock and earth will fall into the space, causing subsidence at the surface.
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.
What The USGS Earthquake Map Tells Us. The color-coded map shows a range of earthquake probability across the U.S. Well known high-risk areas, such as California and Alaska, are coded in dark red ...
USGS map colored by paleogeological areas and demarcating the sections of the U.S. physiographic regions: Laurentian Upland (area 1), Atlantic Plain (2-3), Appalachian Highlands (4-10), Interior Plains (11-13), Interior Highlands (14-15), Rocky Mountain System (16-19), Intermontane Plateaus (20-22), & Pacific Mountain System (23-25) The legend ...
In 2004, a study conducted by the Geological Society of America analyzed the potential for land subsidence along the Cascadia subduction zone. It postulated that several towns and cities on the west coast of Vancouver Island, such as Tofino and Ucluelet, are at risk for a sudden, earthquake initiated, 1–2 m subsidence. [23]