Demining

Demining or mine clearance is the process of removing land mines from an area. In military operations, the object is to rapidly clear a path through a minefield, and this is often done with devices such as mine plows and blast waves. By contrast, the goal of humanitarian demining is to remove all of the landmines to a given depth and make the land safe for human use. Specially trained dogs are also used to narrow down the search and verify that an area is cleared. Mechanical devices such as flails and excavators are sometimes used to clear mines. A great variety of methods for detecting landmines have been studied. These include electromagnetic methods, one of which (ground penetrating radar) has been employed in tandem with metal detectors. Acoustic methods can sense the cavity created by mine casings. Sensors have been developed to detect vapor leaking from landmines. Animals such as rats and mongooses can safely move over a minefield and detect mines, and animals can also be used to screen air samples over potential minefields. Bees, plants and bacteria are also potentially useful. Explosives in landmines can also be detected directly using nuclear quadrupole resonance and neutron probes. Detection and removal of landmines is a dangerous activity, and personal protective equipment does not protect against all types of landmine. Once found, mines are generally defused or blown up with more explosives, but it is possible to destroy them with certain chemicals or extreme heat without making them explode. Land mines overlap with other categories of explosive devices, including unexploded ordnance (UXOs), booby traps and improvised explosive devices (IEDs). In particular, most mines are factory-built, but the definition of landmine can include 'artisanal' (improvised) mines. Thus, the United Nations Mine Action Service includes mitigation of IEDs in its mission. Injuries from IEDs are much more serious, but factory-built landmines are longer lasting and often more plentiful. Over 1999–2016, yearly casualties from landmines and unexploded ordnance have varied between 9,228 and 3,450. In 2016, 78% of the casualties were suffered by civilians (42% by children), 20% by military and security personnel and 2% by deminers. There are two main categories of land mine: anti-tank and anti-personnel. Anti-tank mines are designed to damage tanks or other vehicles; they are usually larger and require at least 100 kilograms (220 lb) of force to trigger, so infantry will not set them off. They contain a lot of metal and so are relatively easy to detect. Anti-personnel mines are designed to maim or kill soldiers. There are over 350 types, but they come in two main groups: blast and fragmentation. Blast mines are buried close to the surface and triggered by pressure. A weight between 4 and 24 pounds (1.8 and 10.9 kg), the weight of a small child, is usually enough to set one off. They are usually cylindrical with a diameter of 2–4 inches (5.1–10.2 cm) and a height of 1.3–3.0 inches (3.3–7.6 cm). Fragmentation mines are designed to explode outwards, in some cases 'bounding' upward and exploding above the ground, resulting in casualties as much as 100 metres away. Their size varies and they are mostly metal, so they are easily detected by metal detectors. However, they are normally activated by tripwires that can be up to 20 metres away from the mine, so tripwire detection is essential. The casing of blast mines may be made of metal, wood or plastic. Some mines, referred to as minimum metal mines, are constructed with as little metal as possible – as little as 1 gram (0.035 oz) – to make them difficult to detect. Common explosives used in land mines include TNT (C7H5N3O6), RDX (C3H6N6O6), pentaerythritol tetranitrate (PETN, O12N8C4H8), HMX (O8N8C4H8) and ammonium nitrate (O3N2H4). Land mines are found in about 60 countries. Deminers must cope with environments that include deserts, jungles and urban environments. Antitank mines are deeply buried while antipersonnel mines are usually within 6 inches of the surface. They may be placed by hand or scattered from airplanes, in regular or irregular patterns. In urban environments, fragments of destroyed buildings may hide them; in rural environments, soil erosion may cover them or displace them. Detectors can be confused by high-metal soils and junk. Thus, demining presents a considerable engineering challenge.