Subsidence is the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level. The opposite of subsidence is uplift, which results in an increase in elevation. Ground subsidence is of concern to geologists, geotechnical engineers and surveyors.

Dissolution of limestone

Subsidence frequently causes major problems in karst terrains, where dissolution of limestone by fluid flow in the subsurface causes the creation of voids (i.e. caves). If the roof of these voids 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 result in sinkholes which can be many hundreds of meters deep.

Mining

Several types of sub-surface mining, and specifically methods which intentionally cause the extracted void to collapse (such as pillar extraction, longwall mining and any metalliferous mining method which utilities "caving" such as "block caving" or "sub-level caving") will result in surface subsidence. Mining induced subsidence is relatively predictable in its magnitude, manifestation and extent, except where a sudden pillar or near-surface underground tunnel collapse occurs (usually very old workings). Mining-induced subsidence is nearly always very localized to the surface above the mined area, plus a margin around the outside. The vertical magnitude of the subsidence itself typically does not cause problems, except in the case of drainage (including natural drainage) - rather it is the associated surface compressive and tensile strains, curvature, tilts and horizontal displacement that are the cause of the worst damage to the natural environment, buildings and infrastructure.

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.

Extraction of natural gas

If natural gas is extracted from a natural gas field the initial pressure (up to 60MPa (600 bar)) in the field will drop over the years. The gas pressure also supports the soil layers above the field. If the pressure drops, the soil pressure increases and this leads to subsidence at the ground level. Major subsidence of the Mississippi River Delta due to oil and gas extraction has caused the ocean to rise and flood over of marshes and land each year. Since 1930, Louisiana has lost .

Since exploration 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.

Earthquake

Geospatial Information Authority of Japan reported immediate subsidence caused by 2011 Tōhoku earthquake. Subsidence is observed on the coast of Pacific Ocean in Tōhoku region, Miyako city 0.50 m (1.64 ft) in north, Rikuzentakata, Iwate 0.84 m (2.75 ft) to Sōma city 0.29 m (0.95 ft) in south, the maximum amount is 1.2 m (3.93 ft) and also diastrophism 5.3 m (17.3 ft) in horizontal toward ESE at Oshika Peninsula Miyagi.

Groundwater-related subsidence

The habitation of lowlands, such as coastal or delta plains, requires drainage. The resulting aeration of the soil leads to the oxidation of its organic components, such as peat, and this decomposition process may cause significant land subsidence. This applies especially when ground water levels are periodically adapted to subsidence, in order to maintain desired unsaturated zone depths, exposing more and more peat to oxygen. In addition to this, drained soils consolidate as a result of increased effective stress. In this way, land subsidence has the potential of becoming self-perpetuating, having rates up to 5 cm/yr. Water management used to be tuned primarily to factors such as crop optimisation but, to varying extents, avoiding subsidence has come to be taken into account as well.

Faulting induced

When differential stresses exist in the Earth, these can be accommodated either by geological faulting in the brittle crust, or by ductile flow in the hotter and more fluid mantle. Where faults occur, absolute subsidence may occur in the hanging wall of normal faults. In reverse, or thrust, faults, relative subsidence may be measured in the footwall.

Isostatic subsidence

The crust floats buoyantly in the plastic asthenosphere, with a ratio of mass below the "surface" in proportion to its own density and the density of the asthenosphere. If mass is added to a local area of the crust (e.g. through deposition), the crust subsides to compensate and maintain isostatic balance. The opposite effect to Isostatic subsidence is known as isostatic rebound - the action of the crust returning (sometimes over periods of thousands of years) to a state of isostacy, such as after the melting of large Ice sheets or the drying-up of large lakes after the last ice age. Lake Bonneville is a famous example: Due to the weight of the water once held in the lake, the Earth's crust subsided nearly to maintain equilibrium, when the lake dried up, the crust rebounded. Today when you go to Lake Bonneville you will find that the center of the former lake is about higher than the distant edges.

Seasonal effects

Many soils contain significant proportions of clay which because of the very small particle size are affected by changes in soil moisture content. Seasonal drying of the soil results in a reduction in soil volume and a lowering of the soil surface. If building foundations are above the level to which the seasonal drying reaches they will move and this can result 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, this 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, over a period which can last as many as 25 years, the surface level around the tree will rise and expand laterally. This is often more damaging to buildings unless the foundations have been strengthened or designed to cope with the effect.

See also

Lateral and subjacent support is a related concept in real property law.

References

External links

Category:Depressions (geology) Category:Soil mechanics Category:Geology Category:Building defects

cs:Subsidence de:Setzung es:Subsidencia eo:Subsidenco (geologio) eu:Subsidentzia fr:Subsidence (géologie) it:Subsidenza nl:Bodemdaling ja:地盤沈下 no:Subsidens nn:Subsidens pl:Subsydencja pt:Subsidência ru:Обвал sk:Subsidencia sv:Sättning (geologi) tr:Sübsidans uk:Обвал

Coordinates	52°0′54″N4°21′24″N
name	Edwyn Collins
background	solo_singer
birth name	Edwyn Stephen Collins
born	August 23, 1959Edinburgh, Scotland
instrument	Vocals, electric guitar
genre	Alternative rock
occupation	Singer-songwriter, musician.
label	Setanta/Epic Records
associated acts	Nu-Sonics, Orange Juice, The Drums
website	www.edwyncollins.com }}

Edwyn Stephen Collins (born 23 August 1959, Edinburgh) is an Ivor Novello Award winning Scottish musician, playing mostly electric guitar-driven pop. Collins formed the musical group Nu-Sonics in 1976, which later became Orange Juice. He has since pursued a solo career as a musician, in addition to work as an illustrator, television actor and producer, and as a record producer.

Career

Orange Juice had a Number-8 hit single with "Rip It Up", their only UK Top 40 single and biggest commercial success. In 1985, Orange Juice disbanded; after some difficulty finding a record label with which to sign, Collins began his solo career a year later after signing with the Elevation subsidiary of Creation Records.

Collins released a 1994 single, "A Girl Like You", which was a hit in both the UK and the U.S. and was featured in the films ''Empire Records'', ''The Secretary'' and ''Charlie's Angels: Full Throttle''. "Magic Piper of Love", a 1997 single that featured on the soundtrack of ''Austin Powers: International Man of Mystery'', was also released.

He built his own recording studio in 1994 and produced his own third solo album, ''Gorgeous George''. He has also worked extensively as a record producer with other artists, including The Proclaimers, A House, Space, Robert Forster, The Cribs, and Little Barrie. In 2005, Collins produced the album ''The New Fellas'' recorded by The Cribs.

In May 2009, he won the Ivors Inspiration Award in recognition of his struggles following a double brain haemorrhage in 2005.

In addition to his music career, Collins has also produced and starred in the Channel 4 sitcom, ''West Heath Yard''. Collins released his first book of illustrations with Morel Books in 2009.

On 2 October 2009, Collins's wife, Grace Maxwell, detailed her "running battle" with Warner Music Group and MySpace over his right to allow fans to listen to "A Girl Like You" for free on his MySpace page.

"Losing Sleep" was released on September 13, 2010 in the UK. It's Collins's first written and recorded album since his serious illness in 2005. It was recorded at his own West Heath Studios between November 2008 and May 2010 and produced by the former Orange Juice frontman and Sebastian Lewsley. He collaborated with The Cribs' Ryan Jarman and Johnny Marr, Franz Ferdinand's Alex Kapranos and Nick McCarthy, The Magic Numbers singer Romeo Stodart, The Drums and Aztec Camera singer Roddy Frame.

Personal life

Collins is married to Grace Maxwell, who is also his manager. The couple live in London and have one son, William, who maintains his father's MySpace page.

In a BBC 6 Music radio interview on 18 February 2005, Collins had said he felt unwell, but ascribed the nausea and vertigo to food poisoning. Two days later, he was admitted to intensive care in London's Royal Free Hospital after apparently suffering a major cerebral hemorrhage. After suffering a second haemorrhage he had an operation on 25 February 2005, which was followed by a lengthy programme of neurological rehabilitation owing to right-sided weakness and difficulty with speech. The aphasia he suffered allowed him to repeat only four phrases, over and over again: "yes", "no", "Grace Maxwell" and "the possibilities are endless".

Collins released his sixth solo album in September 2007 on Heavenly Records entitled ''Home Again''. The album was recorded before his illness but mixed after his discharge from hospital. Collins is still on the road to recovery, and he has returned to singing live, including playing a gig at The Arts Theatre in London. A tribute song, celebrating his return, was recorded by the Indiepop band The Candy Twins. In November 2009 Collins walked on stage at London’s Bloomsbury Ballroom looking dapper in a black suit and leaning on a silver-topped cane, he spoke slowly to the crowd, his right arm curled up at his side. "But when he started to sing, his baritone proved as powerful as ever."

A BBC Scotland documentary, ''Edwyn Collins:Home Again'', was broadcast on 19 May 2008 and narrated by Franz Ferdinand frontman Alex Kapranos. Filmed during 2007, it followed Collins's progress in recovering from his illness, and his first return to live performance at the BBC Electric Proms. He also performed at the Glastonbury Festival, broadcast on 28 June 2008 on BBC Two and at T in the Park on 10 July 2009. On 20 February 2010 he joined The Maccabees onstage at Brixton Academy for their encore, performing vocals on a storming rendition of "Rip It Up."

In 2010, he received an honorary masters degree from the Buckinghamshire New University in recognition of his “strong influences and contribution to the national and international music industry over the last three decades”. On 21 August 2010 he attended the Helmsdale Highland Games as the chieftain, an honour also previously bestowed on his grandfather.

On 30 September 2010, Collins and his band broadcast three numbers live from the Royal Beacon Hotel in Exmouth for BBC Radio 2's Radcliffe and Maconie Show. Music journalist, Stuart Maconie had earlier written his very first ''NME'' article, by reviewing Collins' 1987 gig at the Manchester International.

Saturday 30th July 2011 saw him perform at the IndieTracks festival at the Midland Railway - Butterley

Solo discography

''Hope and Despair'' - Demon, 1989

''Hellbent on Compromise'' - Diablo, 1990

''Gorgeous George'' - Setanta, 1994, UK #8, US #183

''I'm Not Following You'' - Epic, 1997, UK #55

''Doctor Syntax'' - Setanta, 2002

''A Casual Introduction 1981/2001'' - Setanta, 2002 (collection of Orange Juice and solo work)

''Home Again'' - Heavenly Records, 2007, UK #90

''Losing Sleep'' - Heavenly Records, 2010, UK #54

See also

List of Scottish musicians

List of 1990s one-hit wonders in the United States

List of number-one singles in Australia during the 1990s

List of British comedians

Empire Records

References

External links

Official website

BBC's musical biography of Edwyn Collins

Detailed biography

Category:1959 births Category:Living people Category:Scottish rock guitarists Category:Scottish rock singers Category:Scottish singer-songwriters Category:People from Edinburgh Category:Stroke survivors Category:People educated at Bearsden Academy

da:Edwyn Collins de:Edwyn Collins es:Edwyn Collins fr:Edwyn Collins nl:Edwyn Collins ja:エドウィン・コリンズ pl:Edwyn Collins sv:Edwyn Collins