A road destroyed by subsidence and shear, near Castleton, Derbyshire.

A graphic illustrating the different types of ground subsidence.

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[link]

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[link]

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.^{[1][dead link]} 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.^[2] 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[link]

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 34 square miles (88 km²) of marshes and land each year. Since 1930, Louisiana has lost 1,200,000 acres (4,900 km²).

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.^[3]

Earthquake[link]

Geospatial Information Authority of Japan reported immediate subsidence caused by 2011 Tōhoku earthquake. ^[4] 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.^[5]

Groundwater-related subsidence[link]

San Joaquin Valley 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[link]

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[link]

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 200 feet (61 m) 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 200 feet (61 m) higher than the distant edges.

Seasonal effects[link]

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[link]

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

References[link]

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2007)

External links[link]

Wikimedia Commons has media related to: Subsidence

Look up subsidence in Wiktionary, the free dictionary.

v t e Geologic Principles & Processses Stratigraphic Principles Principle of original horizontality Law of superposition Principle of lateral continuity Principle of cross-cutting relationships Principle of faunal succession Principle of inclusions and components Walther's law Petrologic Principles Intrusive Extrusive Exfoliation Weathering Pedogenesis Diagenesis Compaction Metamorphism Geomorphologic Processes Plate tectonics Salt tectonics Tectonic uplift Subsidence Marine transgression Marine regression Sediment transport Fluvial processes Aeolian processes Glacial processes Mass wasting processes

This biographical article needs additional citations for verification. Please help by adding reliable sources. Contentious material about living persons that is unsourced or poorly sourced must be removed immediately, especially if potentially libelous or harmful. (March 2009)

Craig Phillips
Born	(1971-10-16) 16 October 1971 (age 40) Liverpool, England
Residence	London, England
Television	Big Brother 2000 (UK)

Craig Phillips (born 16 October 1971, Liverpool) is an English builder, DIY expert, television personality and presenter, best known for winning the first series of the British reality television show Big Brother. He is trained as a bricklayer and in DIY, appearing in numerous series related to this since 2001.

Biography[link]

The younger of two children, his family moved to Newport, Shropshire in the late 1980s. At 18, Phillips secured a day release bricklayers apprenticeship whilst employed with Wrekin Council’s construction department. Determined to ensure he excelled in his chosen profession, he attended further night school classes in advanced brickwork and civil engineering. Having qualified with a City & Guilds, Phillips went on to set up his own building company. The business quickly went from strength to strength employing more than 30 tradesmen.

After leaving the Big Brother house as its first winner, Phillips announced he was giving his £70,000 prize fund to his friend Joanne Harris, who had Down's syndrome, to pay for her heart and lung transplant. He had begun raising money with friends for Harris sometime before entering Big Brother, raising only small amounts of money towards the £250,000 needed for her operation in the USA, but within 6 days of winning he achieved the target required for her life saving operation thanks to public support and generous donations from celebrities. Harris died in April 2008.^[1]

He has featured in comedy series Bo' Selecta! and appeared in the reality TV series, Back To Reality raising £40,000 for Macmillan Cancer Trust.

At Christmas 2000, Phillips released the charity single, "At This Time of Year" with Warner Music. The single went to Number 14 in the UK Singles Chart,^[2] achieving silver disc status and raising over £40,000 for the Down's Syndrome Association. It stayed in the top 40 for three weeks. Since then he has appeared in videos for two other Xmas singles - "Bo Selectas! Proper Crimbo" which reached No. 4 in 2003 and Ricky Tomlinson's "Xmas My A*se" which reached 25 in 2006.

In the 1990s, before his TV career began, Phillips bought and renovated his first house. He presented Renovation Street with Linda Robson for Carlton ITV before being brought in as the DIY expert for the BBC on an exclusive contract in 2001.

Phillips has now presented as 'resident expert' on a large number of televisions shows across the globe including Housecall (live daily morning show), BBC 1, Housecall In The Country, BBC 1, Builders Sweat and Tears, BBC 1 & UK Style, Our House, UK Style, Trading Up, BBC 1 & UK Style, Big Strong Boys, BBC 1 & UK Style, Boyz In The Wood (2 x 10 part carpentry series) Discovery Realtime, Big Strong Boys In The Sun (Europe), BBC 1, Renovation Street, ITV1 & Discovery Realtime, Sex and the City (Series 4 - Episode 7 (USA) NBC,Trading Up In The Sun (Europe) BBC 1, House Trap, BBC 1 and Craig’s Trade Tips, BBC 1.

He also has a production company called Avent Productions.^[3] For Avent he has presented the programmes Conversion a 10 part series for Discovery Realtime and the sixth series of Hung, Drawn & Quartered, a 6 part series filmed worldwide for British Forces Broadcasting Service. The company also produces corporate productions many of these for building companies.

Craig Phillips teaching DIY

In 2007 Phillips joined the team of 60 Minute Makeover for ITV1. He completed 80 shows in 2008, the first 40 of these aired in late 2008 with a further 40 airing throughout Spring 2009.

February 2009 saw Phillips appear in Ant & Dec's Saturday Night Takeaway in "Escape From Takeaway Prison" for six weeks.

Summer 2009 saw the release of his autobiography with Bantam Press (A division of Transworld). On 29 May 2009, he talked to Petrie Hosken on LBC (London's Biggest Conversation - 97.3 FM) about his time in BB1 and how lots of wannabe's are now entering Big Brother. In July 2009, Phillips returned to the Big Brother house to help celebrate the show's tenth anniversary. He competed in a task against one of the current housemates. He was only in the house for a few hours and was a replacement for Nick Bateman who pulled out of doing the appearance. In 2010, Phillips again re-entered the Big Brother House and completed in a shed building task. He also appeared in Dermot's Last Supper, a show to celebrate the ending of Big Brother.

In April 2011, he hosted a show called Celebrity DIY with Craig Phillips for Home. In 2011, he also became an ambassador for Ryobi. In June 2011 he also hosted If It's Broke, Fit It for Home.

Building school[link]

After two years, research planning and construction Phillips developed the largest independent construction training academy in the North-West, opening its doors in September 2005 to its first 152 students. The facility was formally opened by Cherie Blair QC in January 2006.

The 25,000 sq ft (2,300 m²) facility was designed and built by Phillips and his team to simulate a real construction site with 88 solid individual rooms for various types of wet trades, 48 carpentry bench workstations and a 9,000 sq ft (840 m²) open plan workshop for brickwork - large enough to build several entire houses. Along with the practical workshop areas the academy also consists of 3 large fully equipped I.T classrooms, various staff offices, administration and reception areas.

Within the first six months of running a £1 million pound contract awarded by the Learning and Skills Council. After a year's successful trading, and having achieved full centre accreditation awarded by the Construction Industry Training Board, Phillips transferred ownership to Carter and Carter Group Plc, the country's largest independent training provider.

Charitable support[link]

Phillips is a patron of the Down's Syndrome Association and road safety charity, Brake. In 1985, aged 13, he experienced the personal tragedy of losing his father by a drunk driver. In 2000 he was approached by the Department for Transport to back the governments national 'Think! drink, drive' media campaign. He faced the national media and reflected on his family's experience as he launched the campaign alongside the transport minister.

He was one of the Lord Mayor of Liverpool's chosen charity ambassadors (alongside footballer Kenny Dalglish and musician Gerry Marsden) assisting at events throughout Liverpool's European Capital of Culture 2008. His term as an appeal ambassador ended in May 2009 when the Mayor handover took place. He has also participated in numerous sports events: marathons and distance running, captaining teams at charity golf events, cycle tours, he has played football and tennis for charity at major UK championship venues including Liverpool F.C, Birmingham City F.C., and Wimbledon.

To date he has raised over £500,000 for charities and charitable causes.

Financial[link]

As of May 2009 he had accumulated wealth of £15 million.^[4]

References[link]

This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. Please improve this article by introducing more precise citations. (February 2008)

• [2] British 'Big Brother' prize claimed by builder CNN Article
• [3] Channel 4 Big Brother 1 site
• [4] Interview for UK Style. UK Style Our House
• [5] BBC Skillwise Video
• [6] BBC News | ENTERTAINMENT | Big Brother's Craig still in spotlight
• [7] Craig Phillips - Big Brother Heroes
• [8] Now who’s a good calendar boy, then? PDSA Pet Pawtraits 2008 Celebrity Calendar
• [9] Craig, Terri and daughter Danielle create a TV treat - 60 Minute Makeover ITV1

External links[link]

• Official Craig Phillips website
• Craig Phillips at the Internet Movie Database
• Craig Phillips television and corporate production company website
• Craig Phillips 60 Minute Makeover ITV1 profile

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