Subsidence
Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement,
Processes that lead to subsidence include
Ground subsidence is of global concern to
Causes
Dissolution of limestone
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. This type of subsidence can cause sinkholes which can be many hundreds of meters deep.[6]
Mining
Several types of
Where mining activity is planned, mining-induced subsidence can be successfully managed if there is co-operation from all of the stakeholders. This is accomplished through a combination of careful mine planning, the taking of preventive measures, and the carrying out of repairs post-mining.[10]
Extraction of petroleum and natural gas
If
Since exploitation of the Slochteren (Netherlands) gas field started in the late 1960s the ground level over a 250 km2 area has dropped by a current maximum of 30 cm.[11]
Extraction of
Earthquake
Land subsidence can occur in various ways during an earthquake. Large areas of land can subside drastically during an earthquake because of offset along fault lines. Land subsidence can also occur as a result of settling and compacting of unconsolidated sediment from the shaking of an earthquake.[12]
The Geospatial Information Authority of Japan reported immediate subsidence caused by the 2011 Tōhoku earthquake.[13] In Northern Japan, subsidence of 0.50 m (1.64 ft) was observed on the coast of the Pacific Ocean in Miyako, Tōhoku, while Rikuzentakata, Iwate measured 0.84 m (2.75 ft). In the south at Sōma, Fukushima, 0.29 m (0.95 ft) was observed. The maximum amount of subsidence was 1.2 m (3.93 ft), coupled with horizontal diastrophism of up to 5.3 m (17.3 ft) on the Oshika Peninsula in Miyagi Prefecture.[14]
Groundwater-related subsidence is the subsidence (or the sinking) of land resulting from 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. One estimate has 80% of serious land subsidence problems associated with the excessive extraction of groundwater,[15] making it a growing problem throughout the world.
Groundwater fluctuations can also indirectly affect the decay of organic material. The habitation of
Faulting induced
When differential stresses exist in the Earth, these can be accommodated either by
Isostatic subsidence
The crust floats buoyantly in the
The opposite of isostatic subsidence is known as
Seasonal effects
Many soils contain significant proportions of clay. Because of the very small particle size, they are affected by changes in soil moisture content. Seasonal drying of the soil results in a lowering of both the volume and the surface of the soil. If building foundations are above the level reached by seasonal drying, they move, possibly resulting in damage to the building in the form of tapering cracks.
Trees and other vegetation can have a significant local effect on seasonal drying of soils. Over a number of years, a cumulative drying occurs as the tree grows. That can lead to the opposite of subsidence, known as heave or swelling of the soil, when the tree declines or is felled. As the cumulative moisture deficit is reversed, which can last up to 25 years, the surface level around the tree will rise and expand laterally. That often damages buildings unless the foundations have been strengthened or designed to cope with the effect.[20]
Weight of buildings
High buildings can create land subsidence by pressing the soil beneath with their weight. The problem is already felt in New York City, San Francisco Bay Area, Lagos.[21][22]
Impacts
Sinking cities
See also
- Cave-in
- Lateral and subjacent support, a related concept in property law
- Mass wasting
- Settlement (structural)
- Sinkhole
- Soil liquefaction
- UNESCO Working Group on Land Subsidence
- Sea level rise
References
- ^ ISBN 0922152349.
- ^ ISBN 9780199653065.
- ISBN 0813753031.
- ^ National Research Council, 1991. Mitigating losses from land subsidence in the United States. National Academies Press. 58 p.
- ^ ISBN 0314921958.
- ISBN 978-3-540-20725-2.
- ^ Herrera, G.; Tomás, R.; López-Sánchez, J.M.; Delgado, J.; Mallorquí, J.; Duque, S.; Mulas, J. Advanced DInSAR analysis on mining areas: La Union case study (Murcia, SE Spain). Engineering Geology, 90, 148-159, 2007.
- ^ "Graduated Guidelines for Residential Construction (New South Wales) Volume 1" (PDF). Retrieved 2012-11-19.
- ^ G. Herrera, M.I. Álvarez Fernández, R. Tomás, C. González-Nicieza, J. M. Lopez-Sanchez, A.E. Álvarez Vigil. Forensic analysis of buildings affected by mining subsidence based on Differential Interferometry (Part III). Engineering Failure Analysis 24, 67-76, 2012.
- ^ Bauer, R.A. (2008). "Planned coal mine subsidence in Illinois: a public information booklet" (PDF). Illinois State Geological Survey Circular. 573. Retrieved 10 December 2021.
- ^ Subsidence lecture Archived 2004-10-30 at the Wayback Machine
- ^ "Earthquake Induced Land Subsidence". Retrieved 2018-06-25.
- ^ 平成23年(2011年)東北地方太平洋沖地震に伴う地盤沈下調査 [Land subsidence caused by 2011 Tōhoku earthquake and tsunami] (in Japanese). Geospatial Information Authority of Japan. 2011-04-14. Retrieved 2011-04-17.
- ^ Report date on 19 March 2011, [1] Diastrophism in Oshika Peninsula on 2011 Tōhoku earthquake and tsunami, Diastrophism in vertical 2011-03-11 M9.0, Diastrophism in horizontal 2011-03-11 M9.0 Geospatial Information Authority of Japan
- ^ USGS Fact Sheet-165-00 December 2000
- ^ Tomás, R.; Márquez, Y.; Lopez-Sanchez, J.M.; Delgado, J.; Blanco, P.; Mallorquí, J.J.; Martínez, M.; Herrera, M.; Mulas, J. Mapping ground subsidence induced by aquifer overexploitation using advanced Differential SAR interferometry: Vega Media of the Segura river (SE Spain) case study. Remote Sensing of Environment, 98, 269-283, 2005
- ^ R. Tomás, G. Herrera, J.M. Lopez-Sanchez, F. Vicente, A. Cuenca, J.J. Mallorquí. Study of the land subsidence in the Orihuela city (SE Spain) using PSI data: distribution, evolution, and correlation with conditioning and triggering factors. Engineering Geology, 115, 105-121, 2010.
- ISBN 9780444635907.
- .
- ^ Yirka, Bob. "New York City building weight contributing to subsidence drop of 1–2 millimeters per year". Phys.org. Earth's Future. Retrieved 22 January 2024.
- ^ Novo, Cristina. "The weight of buildings contributes to the sinking of cities". Smart Water Magazine. Retrieved 22 January 2024.
- .
- ^ Fuchs, Roland (July 2010). "Cities at Risk: Asia's Coastal Cities in an Age of Climate Change". Asia Pacific Issues. 96: 1–12.
- ^ Sundermann, L., Schelske, O., & Hausmann, P. (2014). Mind the risk – A global ranking of cities under threat from natural disasters. Swiss Re.