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T-72

The T-72 is a family of Soviet main battle tanks that entered production in 1971. The T-72 was a development based on the T-64 using thought and design of the previous Object 167M. About 25,000 T-72 tanks have been built, and refurbishment has enabled many to remain in service for decades. It has been widely exported and has seen service in 40 countries and in numerous conflicts. The Russian T-90 introduced in 1992 and the Chinese Type 99 are further developments of the T-72. Production and development of various modernized T-72 models continues today.

Development from the T-64
The T-72 was a product of a rivalry between design teams. Morozov KB was led by Alexander Morozov in Kharkiv. Uralvagon KB was led by Leonid Kartsev in Nizhny Tagil.

To improve on the T-62, two designs based on the tank were tested in 1964: Nizhny Tagil's Object 167 (T-62B) and Kharkiv's Object 434.

Ob. 434 was a technically ambitious prototype. Under the direction of Morozov in Kharkiv, a new design emerged with the hull reduced to the minimum size possible. To do this, the crew was reduced to three soldiers, removing the loader by introducing an automated loading system.

Ob. 167 was designed based on an Object 140 rebuilt by Kartsev and Valeri Venediktov. Ob. 167 was more advanced than Kartsev's Ob. 165 and Ob. 166, and was also Kartsev's favored model. In October 1961, when asked to ready Ob. 166 for production, Kartsev disagreed and instead offered to prepare the Ob. 167. This suggestion was rejected, and the Ob. 166 and Ob. 165 were readied as the T-62 and T-62A respectively. Unlike the Kharkiv tank, it eschewed the state-of-the-art prototypes and used the turret from the T-62, and a manual loader. In 1964, the tank underwent comparative testing with the Ob. 434, in which the former proved its superiority to both the T-62 and T-55. Ob. 167 was favored by Uralvagonzavod director I.V. Okunev and Soviet Premier Nikita Khrushchev, who believed the tank was more affordable. Deputy Chairman of the Council of Ministers of the Soviet Union Dmitry Ustinov, believed the parallel development of Ob. 167 jeopardized the future of the Kharkiv tank. In December 1962, the Council of Ministers of the Soviet Union ordered Ob. 432 (later serialized as the T-64) into production, dooming Kartsev's tank.

Kartsev continued to work on the Ob. 167. Ob. 167M incorporated an autoloader. This model too was rejected in May 1964.

Problems with the early production run were evident from the start, but a strong lobby formed around Morozov who advocated for Ob. 434 in Moscow, preventing rival developments and ideas from being discussed. Ob. 434 was accepted into Soviet Army service in May 1968 as the T-64A.

The T-64's smaller design presented a problem when selecting a suitable engine. The chosen 700 hp 5TDF engine was unreliable, difficult to repair, and had a guaranteed lifespan similar to World War II designs.

Object 172
In 1967, the Uralvagonzavod formed "Section 520", which was to prepare the serial production of the T-64 for 1970. Because of the time-consuming construction of the 5TDF engines, which took about twice as long as the contemporary V-45, the Malyshev Factory in Kharkiv could not provide a sufficient number of 5TDF engines for all Soviet tank factories. The Military-Industrial Commission (VPK) authorized work on two alternative engines for a wartime T-64, a so-called "mobilization model" that could be produced more quickly and at half the cost. Obj. 219 (which became the T-80, with a GTD-1000T gas-turbine) was designed in Leningrad. Ob. 439 with a diesel V-45 engine was designed by Uralvagon KB at Uralvagonzavod in Nizhny Tagil.

GABTU sent a T-64A prototype with a team to Uralvagonzavod. Kartsev was to lead this team.

Kartsev was unsatisfied with the innovations of the T-64, and began instead a more comprehensive project to redesign the tank. Kartsev melded what he believed were the best aspects of the T-64A, Object 167, and an upgunned T-62.

During development the tank was code-named "Ural" after the Ural mountain region. Uralvagonzavod produced the first prototype with a T-62 turret, D-81 125-mm gun and V-45 engine in January 1968. Ob. 439 differed so greatly from the T-64 that it was redesignated as "Object 172".

Kartsev's defiance angered GABTU, which initially reprimanded him for his insubordination. However, after the tank proved indeed to possess potential as a less costly alternative to the T-64, Kartsev was allowed to continue work on his design. Politically motivated opposition continued to beset the tank throughout its development. Vagonka tank plant manager I.F. Krutyakov sought to subordinate Uralvagonzavod under Josef Kotin. Kartsev skillfully beat back this play for power, embarrassing Krutyakov in the process. Kartsev retired in August 1969, and was succeeded by Venediktov.

The team soon found out that the more powerful V-45 engine put a lot of stress on the T-64 hull, so that after some time cracks started to materialize. A more stable solution was sought.

Finally, an idea from 1960 was used, when a modification of the T-62 had been discussed: In 1961, two prototypes of "Object 167" had been built by Uralvagonzavod to test a stronger hull and running gear combination for that tank. Under influence from Kharkiv, the idea had been turned down by Moscow. But this construction, with its big, rubbercoated roadwheels now formed the basis for the mobilisation model of the T-64.

Additional changes were made to the automatic loading system, which also was taken from an earlier project, originally intended for a T-62 upgrade. The 125 mm ammunition, consisting of a separate projectile and a propellant charge, was now stored horizontally on two levels, not vertically on one level as in the T-64. It was said to be more reliable than the T-64 autoloader. In 1964, two 125-mm guns of the D-81 type had been used to evaluate their installation in to the T-62, so the Ural plant was ready to adopt the 125 mm calibre for the T-64A as well.

Venediktov's team later replaced the T-64-style suspension with the Obj. 167's suspension. The tank was trialed in Kubinka in 1968, and Central Asia in 1969. After intensive comparative testing with the T-64A, Object 172 was re-engineered in 1970 to deal with some minor problems. Further trials took place in Transbaikal in 1971.

T-72
Being only a mobilisation model, serial production of Object 172 was not possible in peacetime. However, by 1971, even Ustinov was growing tired of problems with the T-64. In an unclear political process decree number 326-113 was issued, which allowed the production of Object 172 in the Soviet Union from 1 January 1972, and freed Uralvagonzavod from the T-64A production.

An initial production run began in 1972 at Nizhni Tagil. These were trialed in the Soviet Army. A final trial batch was built as "Object 172M" and tested in 1973 and accepted into service as the "T-72" in 1974.

Uralvagon KB continued to iterate on the T-72 in a series of block improvements. Obj. 174 introduced ceramic/steel laminate turret armour. The coincidence rangefinder was replaced with a laser rangefinder. Obj. 174 was designated as the T-72A when it entered production in 1978. Turret armour was greatly improved with Obj. 174M. A more powerful V-84 engine was introduced to offset the increased weight. Obj. 174M entered service in 1985 as the T-72B.

At least some technical documentation on the T-72 is known to have been passed to the CIA by the Polish Colonel Ryszard Kukliński between 1971 and 1982.

Production history
The first series production of T-72 Object 172M began in July at UKBM in Nizhny Tagil. However, due to difficulties in getting the factory organised for the change in production from T-64 to T-72, only 30 completed tanks were delivered in 1973. Troubles continued in 1974 where out of a state production quota of 440 only 220 were officially declared, with the actual number of completed tanks being close to 150. As a result, substantial investment in tooling was undertaken. Only after modernisation, could the factory begin full-scale production of the T-72. Nizhny Tagil produced the tank in various modifications until 1992.

The T-72 was the most common tank used by the Warsaw Pact from the 1970s until the collapse of the Soviet Union in 1991. It was also exported to other countries, such as Finland, India, Iran, Iraq, Syria and Yugoslavia, as well as being copied elsewhere, both with and without licenses.

Licensed versions of the T-72 were made in Poland and Czechoslovakia, for Warsaw Pact consumers. These tanks had better and more consistent quality of make but with inferior armour, lacking the resin-embedded ceramics layer inside the turret front and glacis plate armour, replaced with all steel. The Polish-made T-72G tanks also had thinner armour compared to Soviet Army standard (410 mm for turret). Before 1990, Soviet-made T-72 export versions were similarly downgraded for non-Warsaw Pact customers (mostly the Arab countries). Many parts and tools are not interchangeable between the Soviet, Polish and Czechoslovakian versions, which caused logistics problems.

Yugoslavia developed the T-72 into the more advanced M-84, and sold hundreds of them around the world during the 1980s. The Iraqis called their T-72 copies the "Lion of Babylon" (Asad Babil). These Iraqi tanks were assembled from kits sold to them by the Soviet Union as a means of evading the UN-imposed weapons embargo. More modern derivatives include the Polish PT-91 Twardy. Several countries, including Russia and Ukraine, also offer modernization packages for older T-72s.

Various versions of the T-72 have been in production for decades, and the specifications for its armour have changed considerably. Original T-72 tanks had homogeneous cast steel armour incorporating spaced armour technology and were moderately well protected by the standards of the early 1970s. In 1979, the Soviets began building T-72 modification with composite armour similar to the T-64 composite armour, in the front of the turret and the front of the hull. Late in the 1980s, T-72 tanks in Soviet inventory (and many of those elsewhere in the world as well) were fitted with reactive armour tiles.

TPD-K1 laser rangefinder system have appeared in T-72 tanks since 1974; earlier examples were equipped with parallax optical rangefinders, which could not be used for distances under 1000 m. Some export versions of the T-72 lacked the laser rangefinder until 1985 or sometimes only the squadron and platoon commander tanks (version K) received them. After 1985, all newly made T-72s came with reactive armour as standard, the more powerful 840 bhp V-84 engine and an upgraded design main gun, which can fire guided anti-tank missiles from the barrel. With these developments, the T-72 eventually became almost as powerful as the more expensive T-80 tank, but few of these late variants reached the economically ailing Warsaw Pact allies and foreign customers before the Soviet bloc fell apart in 1990. In the 1990s some reserve T-72B were given a minor upgrade of an uprated engine and better gun stabilisation to become the T-72BA. While not a popular upgrade, it solved a temporary supply shortage.

Since 2000, export vehicles have been offered with thermal imaging night-vision gear of French manufacture as well (though it may be more likely that they might simply use the locally manufactured 'Buran-Catherine' system, which incorporates a French thermal imager). Depleted uranium armour-piercing ammunition for the 125 mm gun has been manufactured in Russia in the form of the BM-32 projectile since around 1978, though it has never been deployed, and has less penetration than the later tungsten BM-42 and the newer BM-42M.

In 2010, Russia started an upgrade using the enormous stocks of T-72B's held in reserve. The rebuild tank is called T72B3 (Ob'yekt 184-M3).

In 2018, the 3rd Central Research Institute in Moscow had tested a proof-of-concept demonstration for robotic tank mobility, and was planning to further develop it based on the T-72B3 and other platforms.

In 2022, Ukrainian intelligence sources claimed that the upgrade of the Russian T-72 fleet has slowed during the war in Ukraine while production of the more modern T-90s and T-14 Armatas has slowed down because of the international sanctions affecting the Russian military industry. However, more tanks of T-72 and T-90 types were ordered in August 2022. A new batch of T-72B3M tanks was reportedly delivered in late 2022.

Models
Main models of the T-72, built in the Soviet Union and Russia. Command tanks have K added to their designation for komandirskiy, "command", for example T-72K is the command version of the basic T-72. Versions with reactive armour have V added, for vzryvnoy, "explosive".

 * T-72 Ural (1973)
 * Original version, armed with 125 mm smoothbore tank gun and optical coincidence rangefinder.

 * T-72A (1979)
 * Coincidence rangefinder replaced with laser rangefinder and electronic fire control added, turret front and top being heavily reinforced with composite armour (nicknamed Dolly Parton by US intelligence), provisions for mounting reactive armour, smoke grenade launchers, flipper armour mount on front mudguards, internal changes.

 * T-72M
 * Export version, similar to T-72A but lacking composite armour (decreasing the weight to 37 tonnes), much simpler fire control system, and usually supplied with inferior ammunition compared to the Soviet army standard. Also built in Poland and former Czechoslovakia.

 * T-72B (1985)
 * New main gun, stabilizer, sights and fire control, 9K120 Svir guided missile system, upgraded hull composite armour consisting of high-hardness steel plates, improved composites in the turret armour, improved 840 hp engine.

 * T-72B3 model 2011 (~2010)
 * This upgrade was initiated in 2010 using the enormous stocks of T-72B's held in reserve. They are rebuilt with new technologies including Sosna-U multichannel gunner's sight, new digital VHF radio, improved autoloader, 2A46M-2 gun to accommodate new ammunition, 9K119 Refleks guided missile system. New V-92S2 engine. Kontakt-5 explosive reactive armour. Lacks satellite navigation.

 * T-72B3 model 2016 or T-72B3M
 * Upgrade for T-72B3, with Relikt explosive reactive armour on the sides, side skirts with soft-container reactive armour and slat screens, 2A46M-5 gun with new ammunition, 9K119M Refleks-M guided missile system, V-92S2F 1130 hp engine, automatic transmission, digital display and rear-view camera. Some T-72B3M’s have been observed in Ukraine with a noticeable increase in reverse speed, but there have been no official reports that the reverse transmission had been improved. Often incorrectly referred to as "T-72B4"

The T-72 design has been used into the following foreign models: T-72M4CZ (Czech Republic), PT-91 Twardy (Poland), M-84 (Yugoslavia), M-84AS1 (Serbia), M-84D (Croatia) and Lion of Babylon (Iraq).

Variants
In addition, the T-72 hull has been used as the basis for other heavy vehicle designs, including the following:

 * BMPT Terminator – Heavy convoy and close tank support vehicle.
 * TOS-1 – Thermobaric multiple rocket launcher, with 30-tube launcher in place of the turret.
 * BREM-1 (Bronirovannaya Remonto-Evakuatsionnaya Mashina) – Armoured recovery vehicle with a 12-tonne crane, 25-tonne winch, dozer blade, towing equipment, and tools.
 * IMR-2 (Inzhenernaya Mashina Razgrashdeniya) – Combat engineering vehicle with an 11-tonne telescoping crane and pincers, configurable dozer blade/plough, and mine-clearing system.
 * MTU-72 (Tankovyy Mostoukladchik) – Armoured bridge layer, capable of laying a 50 t capacity bridge spanning 18 m in three minutes.
 * BMR-3 Vepr (Bronirovannaja Mashina Razminirovanija) – Mine clearing vehicle.

Design characteristics
The T-72 shares many design features with other tank designs of Soviet origin. Some of these are viewed as deficiencies in a straight comparison to NATO tanks, but most are a product of the way these tanks were envisioned to be employed, based on the Soviets' practical experiences in World War II.

Weight
The T-72 is extremely lightweight, at forty-one tonnes, and very small compared to Western main battle tanks. Some of the roads and bridges in former Warsaw Pact countries were designed such that T-72s can travel along in formation, but NATO tanks could not pass at all, or just one-by-one, significantly reducing their mobility. The basic T-72 is relatively underpowered, with a 780 hp supercharged version of the basic 500 hp V12 diesel engine originally designed for the World War II-era T-34. The 0.58 m wide tracks run on large-diameter road wheels, which allows for easy identification of the T-72 and descendants (the T-64 family has relatively small road wheels).

The T-72 is designed to cross rivers up to 5 m deep submerged using a small diameter snorkel assembled onsite. The crew is individually supplied with simple rebreather chest-pack apparatuses for emergency situations. If the engine stops underwater, it must be restarted within six seconds, or the T-72's engine compartment becomes flooded due to pressure loss. The snorkeling procedure is considered dangerous, but is important for maintaining operational mobility.

Nuclear, biological, and chemical protection
The T-72 has a nuclear, biological, and chemical (NBC) protection system. The inside of both hull and turret is lined with a synthetic fabric made of boron compound, meant to reduce the penetrating radiation from neutron bomb explosions. The crew is supplied clean air via an air filter system. A slight over-pressure prevents entry of contamination via bearings and joints. Use of an autoloader for the main gun allows for more efficient forced smoke removal compared to traditional manually loaded ("pig-loader") tank guns, so NBC isolation of the fighting compartment can, in theory, be maintained indefinitely.

Interior
Like all Soviet-legacy tanks, the T-72's design has traded off interior space in return for a very small silhouette and efficient use of armour, to the point of replacing the fourth crewman with a mechanical loader. There is a widespread Cold War-era myth that Soviet tanks were so cramped that height constraints were put in place, with a maximum height of 5 ft 4in (163 cm). However, official regulations state that the T-72 allowed for a height of 5 ft 9in (175 cm), which was standard for other tanks at the time. The basic T-72 design has extremely small periscope viewports, even by the constrained standards of battle tanks and the driver's field of vision is significantly reduced when his hatch is closed. The steering system is a traditional dual-tiller layout instead of the easier-to-use steering wheel or steering yoke common in modern Western tanks. This set-up requires the near-constant use of both hands, which complicates employment of the seven speed manual transmission.

Armour
Armour protection of the T-72 was strengthened with each succeeding generation. The original T-72 "Ural" Object 172M's (from 1973) turret is made from conventional cast high hardness steel (HHS) armour with no laminate inserts. It is believed that the maximum thickness is 280 mm and the nose is 80 mm. The glacis of the new laminated armour is 205 mm thick, comprising 80 mm HHS, 105 mm double layer of laminate and 20 mm RHA steel, which when inclined gives about 500 - 600 mm thickness along the line of sight. In 1977 the armour of the T-72 Object 172M was slightly changed. The turret now featured insert filled with ceramic sand bars "kwartz" rods and the glacis plate composition was changed. It was now made up of 60 mm HHA steel, 105 mm glass Tekstolit laminate and 50 mm RHA steel. This version was often known in Soviet circles as T-72 "Ural-1". The next armour update was introduced by the T-72A (Object 176), which was designed in 1976 and replaced the original on the production lines during 1979–1985. T-72 Object 1976 is also known as T-72A. With the introduction of the T-72B (Object 184) in 1985, the composite armour was again changed. According to retired major, James M. Warford, variants developed after the T-72 base model and T-72M/T-72G MBT, featured a cast steel turret that included a cavity filled with quartz or sand in a form similar to US "fused-silica" armour. The T-72 Model 1978 (Obiekt 172M sb-4), which entered production in 1977, featured a new turret with special armour composed of ceramic rods.

The T-72A featured a new turret with thicker, nearly vertical, frontal armour. Due to its appearance, it was unofficially nicknamed "Dolly Parton" armour by the US Army. This used the new ceramic-rod turret filler, incorporated improved glacis laminate armour, and mounted new anti-shaped-charge sideskirts.

The T-72M was identical to the base T-72 Ural model in terms of protection, retaining the monolithic steel turret. The modernized T-72M1 was closer to the T-72A in terms of protection. It featured an additional 16 mm of high hardness steel appliqué armour on the glacis plate, which produced an increase of 43 mm in line of sight thickness. It was also the first export variant with composite armour in the turret, containing ceramic rods sometimes called "sandbar armour". The turret armour composition was essentially identical to the T-72 "Ural-1" whereas Soviet-only T-72As had slightly increased turret protection.

Several T-72 models featured explosive reactive armour (ERA), which increased protection primarily against high-explosive anti-tank (HEAT) type weapons. Certain late-model T-72 tanks featured Kontakt-5 ERA, a form of universal ERA partly effective against kinetic penetrators. It was added to the T-72 as a response to testing conducted by the Soviet Union against captured Israeli Magach-4 tanks which found that the glacis of the T-72 could be penetrated by the 105mm M111 APDSFS Hetz ammunition.

Late model T-72s, such as the T-72B, featured improved turret armour, visibly bulging the turret front—nicknamed "super-Dolly Parton" armour by Western intelligence. The turret armour of the T-72B was the thickest and most effective of all Soviet tank armour; it was even thicker than the frontal armour of the T-80B. The T-72B used a new "reflecting-plate armour" (bronya s otrazhayushchimi listami), in which the frontal cavity of the cast turret was filled with a laminate of alternating steel and non-metallic (rubber) layers. The glacis was also fitted with 20 mm of appliqué armour. The late production versions of the T-72B/B1 and T-72A variants also featured an anti-radiation layer on the hull roof.

Early model T-72s did not feature side skirts; instead, the original base model featured gill or flipper-type armour panels on either side of the forward part of the hull. When the T-72A was introduced in 1979, it was the first model to feature the plastic side skirts covering the upper part of the suspension, with separate panels protecting the side of the fuel and stowage panniers.

After the collapse of the USSR, US and German analysts had a chance to examine Soviet-made T-72 tanks equipped with Kontakt-5 ERA, and they proved impenetrable to most Cold War US and German tank projectiles and anti-tank weapons. A U.S. Army spokesperson claimed at the show, "the myth of Soviet inferiority in this sector of arms production that has been perpetuated by the failure of downgraded T-72 export tanks in the Gulf Wars has, finally, been laid to rest. The results of these tests show that if a NATO/Warsaw Pact confrontation had erupted in Europe, the Soviets would have had parity (or perhaps even superiority) in armour". KE-effective ERA, such as Kontakt-5, drove the development of M829A3 ammunition.

Late 1980s, Soviet developed Object 187 (Объект 187, or T-72BI), it was a parallel project to Object 188 (the T-90 tank). It was based on the T-72B, with a heavily modified turret. The 'Object 187' used composite armour for the turret ("Super Dolly Parton" composite armour) and the hull front, and RHA for the rest of the tank. It possibly consisted of special materials including ceramic or high density uranium alloys. Maximum physical thickness of the passive armour (not counting the reactive armour – ERA) was up to 950 mm RHA. With Kontakt-5 ERA, T-72BI's frontal armour was immune to the NATO's 120 mm L/44 tank gun. However, after the Soviet collapse, the tank was not accepted.

In 2021, Russian Army T-72B3s were seen fitted with raised mesh screens above their turrets. The screens appeared to act as a type of slat armour attempting to protect the tanks from top attack weapons such as the FGM-148 Javelin ATGM and small air-to-ground munitions fired from unmanned aerial vehicles (UAVs).

Estimated protection level
The following table shows the estimated protection level of different T-72 models in rolled homogeneous armour equivalency, i.e., the composite armour of the turret of a T-72B offers as much protection against an armour-piercing fin-stabilized discarding sabot (APFSDS) round as a 520 mm thick armour steel layer.

Possible easy replacement of Kontakt 5 (or 1) with Relikt. Relikt defends against tandem-charge warheads and reduces penetration of APFSDS rounds by over 50 percent. Calculation T-72B + Relikt vs APFSDS, on turret 1,000–1,050 mm, on hull 950–1,000 mm. For T-90MS Relikt is a basic set, for the T-90S basic set – Kontakt 5.

Gun
The T-72 is equipped with the 125 mm 2A46 series main gun, a significantly larger (20-mm larger) calibre than the standard 105 mm gun found in contemporary Western MBTs, and still slightly larger than the 120 mm/L44 found in many modern Western MBTs. As is typical of Soviet tanks, the gun can fire anti-tank guided missiles, and standard main gun ammunition, including HEAT and APFSDS rounds.

The original T-72 Object 172M (1973) used the 2A26M2 model gun, which had been first mounted on the T-64. The barrel had a length of 6350 mm or 50.8 calibers and had a maximum rated chamber pressure of 450 MPa. The cannon had an electroplated chrome lining but lacked a thermal sleeve. The cannon was capable of firing 3VBM-3 rounds with 3BM-9 steel projectile sabot and 3VBM-6 rounds with 3BM-12 Tungsten sabot APFSDS projectile, allowing respectively 245 mm and 280 mm penetration of RHA steel at 2000m at a 0-degree angle. In addition to APFSDS rounds, T-72 Object 172M could also fire 3VBK-7 rounds incorporating 3BK-12 HEAT warheads and 3VBK-10 rounds incorporating 3BK-14 HEAT warheads. HEAT rounds allowed respectively 420 mm and 450 mm penetration of RHA steel at a 0-degree angle. The High Explosive rounds provided included 3WOF-22 rounds with 3OF-19 warheads or 3WOF-36 rounds with 3OF-26 warheads. For all types of rounds, Zh40 propellant was used. Complementing the original gun setup was a 2E28M "Siren" two-plane electrohydraulic stabilizer allowing automatic stabilization with speeds from 0.05 to 6 degrees per second.

Even as the T-72 Object 172M (1973) was entering production new ammunition was developed to offset armour developments in the West. Beginning in 1972, two new APFSDS rounds were introduced, the 3VBM-7 round with 3BM-15 Tungsten sabot projectile and the "cheaper" 3VBM-8 round with 3BM-17 sabot but without the tungsten carbide plug. These allowed penetration of respectively 310 mm and 290 mm RHA steel at 2000 m at 0-degree angle. At the same time, a universal Zh52 propellant charge was introduced. The 3VBM-7 was the most common APFSDS round found in T-72 Object 172M tanks during the 1970s.

The stated barrel life expectancy of the 2A26M2 model gun was 600 rounds of HE/HEAT equivalent to 600 EFC (Effective Full Charge) or 150 rounds of APFSDS. The main gun of the T-72 has a mean error of 1 m at a range of 1800 m. Its maximum firing distance is 3000 m, due to limited positive elevation. The limit of aimed fire is 4000 m with the gun-launched anti-tank guided missile. The T-72's main gun is fitted with an integral pressure reserve drum, which assists in rapid smoke evacuation from the bore after firing. The 125 millimeter gun barrel is certified strong enough to ram the tank through forty centimeters of iron-reinforced brick wall, though doing so will negatively affect the gun's accuracy when subsequently fired.

The vast majority of T-72s do not have advanced FLIR thermal imaging sights, which allow night vision at longer ranges and with no infrared lamps. Most of the T-72s possess the characteristic 'Luna' Infrared illuminator. Export upgrades allow for installation of advanced night sights.

Autoloader
Like the earlier domestic-use-only T-64, the T-72 is equipped with an automatic loading system, eliminating the need for a dedicated crewmember, decreasing the size and weight of the tank. However, the autoloader is of a noticeably different design. Both the T-64 and T-72 carry their two-section 125 mm ammunition (shell and full propellant charge, or missile and reduced propellant charge) in separate loading trays positioned on top of each other; but firstly, in T-64, 28 of these were arranged vertically as a ring under the turret ring proper, and were rotated to put the correct tray into position under the hoist system in the turret rear. This had the disadvantage of cutting the turret off from the rest of the tank, most notably, the driver. Accessing the hull required partial removal of the trays. The T-72 uses a design that has lower width requirements and does not isolate the turret compartment: the trays are arranged in a circle at the very bottom of the fighting compartment; the trade-off is the reduction of the number of trays to 22. The second difference is that in the T-64 the trays were hinged together and were flipped open as they were brought into position, allowing both the shell/missile and propellant charge to be rammed into the breech in one motion; in the T-72 the tray is brought to the breech as-is, with the shell in the lower slot and the charge in the upper one, and the mechanical rammer sequentially loads each of them, resulting in a longer reloading cycle.

The autoloader has a minimum cycle of 6.5 seconds (ATGM 8 seconds) and a maximum cycle of 15 seconds for reload, in later versions the sequence mode allows to reload in less than 5 seconds, allowing to reach 3 shots in 13 seconds.

The autoloader system also includes an automated casing removal mechanism that ejects the propellant case through an opening port in the back of the turret during the following reload cycle.

The autoloader disconnects the gun from the vertical stabilizer and cranks it up three degrees above the horizontal in order to depress the breech end of the gun and line it up with the loading tray and rammer. While loading, the gunner can still aim because he has a vertically independent sight. With a laser rangefinder and ballistic computer, final aiming takes at least another three to five seconds, but it is pipelined into the last steps of auto-loading and proceeds concurrently.

In addition to the 22 autoloaded rounds, the T-72 carries 17 rounds conventionally in the hull, which can be loaded into the emptied autoloader trays or directly into the gun.

The T-72B3 modernization replaced the old autoloader with a new one to fit longer projectiles such as 3BM59 and 3BM60. Previous variants are limited and may only carry older APFSDS rounds that can not exceed a certain length, therefore allowing less performance from anti-tank rounds.

The way that the unused rounds are stored in the autoloader system has been exposed as a flaw, as observers have noted that penetrating hits can easily set off a chain reaction that detonates all of the ammunition. The result is the turret is blown off resulting in a so-called "jack-in-the-box" explosion. This vulnerability was first observed during the Gulf War. However, contrary to popular belief, the flaw is mostly related to the spare ammunition in the turret, outside of the autoloader. The autoloaders have some ballistic protection, but only hold roughly half of a T-72’s ammunition. During the Chechen war in 1994, the Russians were able to reduce their losses by having their tanks carry fewer rounds so that all the ammunition and propellant was stored in the autoloaders.

Operators and service

The T-72 was never used in the Afghanistan War. The 40th Soviet Army that was deployed there had mainly T-55, and T-62 tanks.

The Russian Federation had over 10,000 T-72 tanks in use, including around 2,000 in active service and 8,000 in reserve (mostly T-72Bs). The T-72 has been used by the Russian Army in the fighting during the First and Second Chechen Wars, the Russo-Georgian War, and the Russo-Ukrainian War. The T-72 has been used by over 40 countries worldwide.

Syria
In the 1982 Lebanon War, Syrian T-72s are believed to have engaged Israeli tanks (M60A1, Magach or possibly Merkava tanks) in the south of Lebanon. It is assumed that Syrian T-72 never met the Merkava in battle. On 9 June 1982, the Syrian General HQ ordered a brigade of the 1st Armoured Division, recently equipped with T-72 tanks, to move straight ahead, cross the border, and hit the right flank of the Israeli units advancing along the eastern side of Beka'a valley. The ensuing battle staved off further Israeli advance and 10 IDF main battle tanks were destroyed. After the war, Syrian president Hafez Al-Assad called it "the best tank in the world".

The T-72 has been in extensive use in the Syrian Civil War by the Syrian Arab Army since 2011. Several captured units have been used by anti-government forces, including the rebel Free Syrian Army, and jihadist groups such as the Islamic Front and the Islamic State of Iraq and Syria.

Initially, the insurgent forces used IEDs and RPG-7 ambush tactics against the government armoured forces. Later, the rebels obtained modern Russian RPGs and Yugoslav M79 Osas, which were used successfully against T-72s. Starting in 2012, the capture from Syrian stocks and later direct delivery by external sponsors of modern anti-tank guided missiles, including Chinese-made HJ-8, Soviet-made 9K111 Fagot, 9M113 Konkurs, and 9K115 Metis, and U.S.-made BGM-71 TOW missile enabled the opposition forces to engage and destroy any government armoured vehicle types, T-72 included, from safer distances. As of March 2020, at least 837 T-72 tanks operated by the Syrian armed forces were destroyed according to visual recordings.

Iraq
Iraqi T-72 Ural (1973)s, T-72 Ural Modernization, T-72Ms and T-72M1s were used successfully throughout the Iran-Iraq War and in countless operations, among others Operation Nasr, in the battle for Basra and during the Tawakalna ala Allah Operations. 105 mm M68 tank guns and TOW missiles proved ineffective against the frontal armour of Iraqi T-72s. Sixty T-72 tanks were lost during the eight years of war. Ra'ad Al-Hamdani, an Iraqi general in the Iraqi Republican Guard, stating "The 16th Iranian Armoured Division, which was equipped with Chieftain tanks, lost a battle against the 10th Iraqi Armoured Brigade with T-72 tanks. It is hard for an armoured brigade to destroy a division in 12 hours but it happened; it was a disaster for the Iranians". Out of the 894 Chieftain tanks that had started the war only 200 were left by the war's end. The 3BM9 APFSDS shell was more than enough to deal with any NATO tank of the time, including the most heavily armoured such as the M60A1 and the Chieftain. According to a Soviet analysis of an Iranian Chieftain captured by the Iraqi army during the early part of the Iran-Iraq war, the Chieftain Mk.5 was considered to have totally insufficient protection even at its strongest points. The frontal part of the entire turret, hull upper front plate and lower front plate could all be defeated at 3 km or more. This essentially means that the T-72 Ural could defeat one of NATO's toughest tanks at any reasonable combat distance. According to Iranians and Iraqis, the T-72 was the most feared tank of the Iran–Iraq War.

During the invasion of Kuwait Iraq used 690 tanks, mainly T-55s, T-62s and T-72s. Kuwait had 281 tanks, including 6 T-72s, 165 Chieftains, 70 Vickers and 40 Centurions. On the morning of 2 August, near the Mutla Pass, a tank battle took place between the Vickers tanks of the 6th Kuwaiti Mechanized Brigade and the T-72s of the Republican Guard's 17th Armoured Brigade, 1st Hammurabi Armoured Division. Kuwaiti tanks were able to knock out one T-72 during the ambush, but were defeated in response with the commander of the 6th brigade captured. Only 20 surviving Vickers tanks were able to retreat to Saudi Arabia.

The Iraqi-assembled T-72 version Lion of Babylon engaged coalition forces in both Iraq wars. The Battle of 73 Easting took place during a sandstorm in the Iraqi desert. U.S. M1A1s and Bradley Fighting Vehicles came up against Iraqi Republican Guard T-72Ms and BMPs and inflicted 37 losses on the Iraqi armoured forces, while losing a single Bradley to enemy fire. The primary attack was conducted by 2ACR's three squadrons of about 400 soldiers, along with the 1st Infantry Division's two leading brigades, who attacked and destroyed the Iraqi 18th Mechanized Brigade and 37th Armoured Brigade of the Tawakalna Division, each consisting of between 2,500 and 3,000 personnel. The Iraqi T-72Ms used 3BM9 shells (removed from Soviet service in 1973),   with a penetration of 245 mm at a distance of up to 2500 meters. M60A1s of the 1st Marine Division Task Force Ripper led the drive to the Kuwait International Airport on 27 February 1991. Task Force Ripper's M60A1 tanks destroyed about 100 Iraqi tanks and armoured personnel carriers, including T-72 tanks. The total number of T-72s lost during Operation Desert Storm was approximately 150.

As of 1996, Iraq had 776 T-72 tanks in service from 1,038 originally received.

Chechen wars
During the First Chechen War (December 1994 to September 1996) fought between the Russian Federation and the self-proclaimed Chechen Republic of Ichkeria, led by Dzhokhar Dudayev, the Russian Federation deployed both T-72 and T-80 tanks. Russian AFV losses during the first three months fighting amounted to 62 tank (T-72/T-80) losses (44 T-72s of 141, 18 T-80s of 71 and 0 PT-76s of 9). Analysis of damage to non repairable vehicles showed that no T-72 were lost to frontal penetration of the hull from man portable anti tank weapons.

Analysis of the causes of these losses indicated the majority were caused by Chechen four-man anti-armour hunter-killer teams consisting of a gunner armed with a Russian RPG-7 or RPG-18 shoulder-fired antitank rocket launcher, and a machine gunner and a sniper, with five or six such teams simultaneously attacking a single armoured vehicle. The majority of losses recorded occurred from three to six kill shot hits to the sides, top and rear of a vehicle.

Highlighted were serious tactical deployment failures, once again demonstrating doctrine and tactics being a primary factor in determining a tank's worth. Following the serious losses to the Russian Federation during their first assault upon Grozny, armoured tactics were revised. Russian armoured vehicle losses dropped off with their change in tactics to have Russian infantry move in front, with armoured combat vehicles in support of the infantry. In particular use of AAA armoured vehicles, these vehicles can elevate their main armament to higher angles than the T-72.

The Russian army captured seven of Dudayev's T-72s and used them in combat. During the First Chechen War, at least two tank duels took place. In the first, Dudayev's T-72A knocked out one T-62M belonging to pro-Russian Chechens. In the second, one of Dudayev's T-72As was destroyed by a Russian T-72B. Three Russian T-72s are recorded as destroyed, at the hands of Chechen separatists, including one tank during the Second Chechen War, during the period 1997 to 2003.

Russo-Georgian War
During the war in South Ossetia in 2008 both sides deployed great numbers of T-72 tanks. At the time of the conflict, the Georgian military fielded 191 T-72 tanks of which 120 were modified to T-72SIM1s. The Georgian army deployed a total of 75 of its T-72 tanks into South Ossetia. The Georgian military lost 30 T-72s, ten in combat during the fighting around Tskhinvali, and another 20 destroyed by Russian paratroopers after their capture.

War in Donbas
On 26 August 2014, the International Institute for Strategic Studies claimed that it had identified a mixed Russian column composed of at least 3 T-72Bs and a lone T-72B3 in the war in Donbas. The significance of this sighting was that Russia attempted to maintain plausible deniability over the issue of supplying tanks and other arms to the separatists. Russia continuously claimed that any tanks operated by the separatists must have been captured from Ukraine's own army. The T-72B3 is in service with the Russian Army in large numbers. This modernized T-72 is not known to have been exported to nor operated by any other country.

In an interview with Dorzhi Batomunkuev in March 2015, it was revealed that he had operated a T-72B as part of a 32 tank Russian army unit when fighting for Debaltseve in Ukraine in February 2015. His tank was destroyed and he suffered severe burns.

Before the conflict Ukraine had 600 T-72s in storage. However, encountering a deficiency of serviceable armoured vehicles, the Ukrainian Ministry of Defence began returning some of the T-72s to service.

Russian invasion of Ukraine
The T-72 has seen extensive service in the 2022 Russian invasion of Ukraine with both sides.

Russia's most numerous tank is the T-72B3 (mod. 2011 and 2016) and the older T-72B (mod. 1985 and 1989). In the buildup to the invasion, Russian forces applied improvised steel grilles to the top of the turret, known as "cope cages" by some commentators. Military analysts have speculated that such grilles were added in an attempt to counter the usage of top-attack weapons, such as the US made FGM-148 Javelin and British-Swedish NLAW, by Ukrainian forces. These implementations add weight to the tank, increase its visual profile, and make it more difficult for the crew to escape from the tank. Analysts have also speculated that they may be potentially used as a countermeasure against RPG-7s fired from above during urban combat, loitering munitions, or against drone attacks, as a response to lessons learned from the 2020 Nagorno-Karabakh war. The lack of uniformity between the makeshift cage variants made from different meshes and iron fences suggest that they are largely improvised by the tank crews, and are not standard issue. In May 2022, some Russian tankers said they eventually removed the cages, as they obstructed the use of machine guns and radios, and prevented evacuation if the tank caught fire. As of 8 July 2024, Russia has lost a total of 1,504 T-72s of all variants according to Oryx.

Before the invasion, Ukraine owned T-72s left from the Soviet Union but were partly modernized. These mainly included T-72As and T-72AVs, as well as modernized T-72AMTs (mod. 2017). On 3 April, an image of a rare T-72 "Ural" (1973) equipped with Kontakt-1 ERA having been damaged appeared. As of April 2022, an unspecified number of Czech T-72M1s had been provided to Ukraine. Poland also donated over 200 T-72M1/M1R tanks to Ukraine. The Ukrainian Army had lost a total of 247 T-72 tanks as of June 19, 2024, according to Oryx.

Combat history

 * 1980–1988: Iran–Iraq War (Iraq)
 * 1982: Lebanon (Syria)
 * 1982: 1982 Ethiopian-Somali Border War (Ethiopia)
 * 1987–1990: Sri Lankan Civil War (India)
 * 1988–1994: First Nagorno-Karabakh War (Armenia and Azerbaijan)
 * 1988–1993: Georgian Civil War (Georgia)
 * 1990–1991: First Persian Gulf War (Iraq, Kuwait)
 * 1990–2002: Sierra Leone Civil War (Executive Outcomes)
 * 1991–2001: Yugoslav Wars (Yugoslavia)
 * 1991: Ten-Day War (Yugoslavia)
 * 1991–1995 Croatian War of Independence (Yugoslavia, Krajina Serbs, Croatia and Republika Srpska)
 * 1998: Kosovo War (Yugoslavia)
 * 2001: 2001 Macedonia conflict (Macedonia)
 * 1991–2002: Algerian Civil War (Algeria)
 * 1991: 1991 Iraqi uprisings (Iraq)
 * 1991: August Coup (Soviet Union)
 * 1992–1997: Civil war in Tajikistan (Russia and Tajikistan)
 * 1994: Rwanda Civil War (Uganda)
 * 1994–1996: First Chechen War (Russia and Chechnya (limited)) First known case of using tank-launched missiles, which effectively destroy targets at 4 km range.
 * 1999–2009: Second Chechen War (Russia)
 * 2003: Invasion of Iraq (Iraq)
 * 2008: Russo-Georgian War (Russia and Georgia)
 * 2011–Present: Syrian Civil War Government forces using T-72 tanks. Opposition forces using captured government's tanks
 * 2011: 2011 Libyan civil war (Gaddafi Government and Anti-Gaddafi forces)
 * 2013–2020: South Sudanese Civil War
 * 2014–present: Russo-Ukrainian War (Ukraine, Russia and pro-Russian separatists)
 * 2014: 2014 Pro-Russian unrest in Ukraine (Ukraine, pro-Russian separatists)
 * 2014: Annexation of Crimea (Russia)
 * 2014–2022: War in Donbas
 * 2022–present: Russian invasion of Ukraine
 * 2014–2017: War in Iraq (2013-2017) (Iraq)
 * 2015: Boko Haram insurgency (Nigeria)
 * 2016: 2016 Nagorno-Karabakh clashes (Armenia and Azerbaijan)
 * 2020: Second Nagorno-Karabakh war (Armenia and Azerbaijan)
 * 2020–2021: 2020–2021 China–India skirmishes (India)
 * 2020–2022: Tigray War (Ethiopia and Tigray Defense Forces)
 * 2022: 2022 Kyrgyzstan–Tajikistan clashes (Tajikistan)
 * 2023: War in Sudan (Sudanese government forces)

title: T-72


text:
Sinkhole

A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are also known as shakeholes, and to openings where surface water enters into underground passages known as ponor, swallow hole or swallet. A cenote is a type of sinkhole that exposes groundwater underneath. Sink and stream sink are more general terms for sites that drain surface water, possibly by infiltration into sediment or crumbled rock.

Most sinkholes are caused by karst processes – the chemical dissolution of carbonate rocks, collapse or suffosion processes. Sinkholes are usually circular and vary in size from tens to hundreds of meters both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may form gradually or suddenly, and are found worldwide.

Natural processes
Sinkholes may capture surface drainage from running or standing water, but may also form in high and dry places in specific locations. Sinkholes that capture drainage can hold it in large limestone caves. These caves may drain into tributaries of larger rivers.

The formation of sinkholes involves natural processes of erosion or gradual removal of slightly soluble bedrock (such as limestone) by percolating water, the collapse of a cave roof, or a lowering of the water table. Sinkholes often form through the process of suffosion. For example, groundwater may dissolve the carbonate cement holding the sandstone particles together and then carry away the lax particles, gradually forming a void.

Occasionally a sinkhole may exhibit a visible opening into a cave below. In the case of exceptionally large sinkholes, such as the Minyé sinkhole in Papua New Guinea or Cedar Sink at Mammoth Cave National Park in Kentucky, an underground stream or river may be visible across its bottom flowing from one side to the other.

Sinkholes are common where the rock below the land surface is limestone or other carbonate rock, salt beds, or in other soluble rocks, such as gypsum, that can be dissolved naturally by circulating ground water. Sinkholes also occur in sandstone and quartzite terrains.

As the rock dissolves, spaces and caverns develop underground. These sinkholes can be dramatic, because the surface land usually stays intact until there is not enough support. Then, a sudden collapse of the land surface can occur.

Space and planetary bodies
On 2 July 2015, scientists reported that active pits, related to sinkhole collapses and possibly associated with outbursts, were found on the comet 67P/Churyumov-Gerasimenko by the Rosetta space probe.

Artificial processes

Collapses, commonly incorrectly labeled as sinkholes, also occur due to human activity, such as the collapse of abandoned mines and salt cavern storage in salt domes in places like Louisiana, Mississippi and Texas, in the United States of America. More commonly, collapses occur in urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids.

Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger a collapse of the roof of an existing void or cavity in the subsurface, resulting in development of a sinkhole.

Solution sinkholes
Solution or dissolution sinkholes form where water dissolves limestone under a soil covering. Dissolution enlarges natural openings in the rock such as joints, fractures, and bedding planes. Soil settles down into the enlarged openings forming a small depression at the ground surface.

Cover-subsidence sinkholes
Cover-subsidence sinkholes form where voids in the underlying limestone allow more settling of the soil to create larger surface depressions.

Cover-collapse sinkholes
Cover-collapse sinkholes or "dropouts" form where so much soil settles down into voids in the limestone that the ground surface collapses. The surface collapses may occur abruptly and cause catastrophic damages. New sinkhole collapses can also form when human activity changes the natural water-drainage patterns in karst areas.

Pseudokarst sinkholes
Pseudokarst sinkholes resemble karst sinkholes but are formed by processes other than the natural dissolution of rock.

Human accelerated sinkholes
The U.S. Geological Survey notes that "It is a frightening thought to imagine the ground below your feet or house suddenly collapsing and forming a big hole in the ground." Human activities can accelerate collapses of karst sinkholes, causing collapse within a few years that would normally evolve over thousands of years under natural conditions. Soil-collapse sinkholes, which are characterized by the collapse of cavities in soil that have developed where soil falls down into underlying rock cavities, pose the most serious hazards to life and property. Fluctuation of the water level accelerates this collapse process. When water rises up through fissures in the rock, it reduces soil cohesion. Later, as the water level moves downward, the softened soil seeps downwards into rock cavities. Flowing water in karst conduits carries the soil away, preventing soil from accumulating in rock cavities and allowing the collapse process to continue.

Induced sinkholes occur where human activity alters how surface water recharges groundwater. Many human-induced sinkholes occur where natural diffused recharge is disturbed and surface water becomes concentrated. Activities that can accelerate sinkhole collapses include timber removal, ditching, laying pipelines, sewers, water lines, storm drains, and drilling. These activities can increase the downward movement of water beyond the natural rate of groundwater recharge. The increased runoff from the impervious surfaces of roads, roofs, and parking lots also accelerate man-induced sinkhole collapses.

Some induced sinkholes are preceded by warning signs, such as cracks, sagging, jammed doors, or cracking noises, but others develop with little or no warning. However, karst development is well understood, and proper site characterization can avoid karst disasters. Thus most sinkhole disasters are predictable and preventable rather than "acts of God". The American Society of Civil Engineers has declared that the potential for sinkhole collapse must be a part of land-use planning in karst areas. Where sinkhole collapse of structures could cause loss of life, the public should be made aware of the risks.

The most likely locations for sinkhole collapse are areas where there is already a high density of existing sinkholes. Their presence shows that the subsurface contains a cave system or other unstable voids. Where large cavities exist in the limestone large surface collapses can occur, such the Winter Park, Florida sinkhole collapse. Recommendations for land uses in karst areas should avoid or minimize alterations of the land surface and natural drainage.

Since water level changes accelerate sinkhole collapse, measures must be taken to minimize water level changes. The areas most susceptible to sinkhole collapse can be identified and avoided. In karst areas the traditional foundation evaluations (bearing capacity and settlement) of the ability of soil to support a structure must be supplemented by geotechnical site investigation for cavities and defects in the underlying rock. Since the soil/rock surface in karst areas are very irregular the number of subsurface samples (borings and core samples) required per unit area is usually much greater than in non-karst areas.

In 2015, the U.S. Geological Survey estimated the cost for repairs of damage arising from karst-related processes as at least $300 million per year over the preceding 15 years, but noted that this may be a gross underestimate based on inadequate data. The greatest amount of karst sinkhole damage in the United States occurs in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. The largest recent sinkhole in the USA is possibly one that formed in 1972 in Montevallo, Alabama, as a result of man-made lowering of the water level in a nearby rock quarry. This "December Giant" or "Golly Hole" sinkhole measures 425 ft long, 350 ft wide and 150 ft deep.

Other areas of significant karst hazards include the Ebro Basin in northern Spain; the island of Sardinia; the Italian peninsula; the Chalk areas in southern England; Sichuan, China; Jamaica; France; Croatia; Bosnia and Herzegovina; Slovenia; and Russia, where one-third of the total land area is underlain by karst.

Occurrence
Sinkholes tend to occur in karst landscapes. Karst landscapes can have up to thousands of sinkholes within a small area, giving the landscape a pock-marked appearance. These sinkholes drain all the water, so there are only subterranean rivers in these areas. Examples of karst landscapes with numerous massive sinkholes include Khammouan Mountains (Laos) and Mamo Plateau (Papua New Guinea). The largest known sinkholes formed in sandstone are Sima Humboldt and Sima Martel in Venezuela.

Some sinkholes form in thick layers of homogeneous limestone. Their formation is facilitated by high groundwater flow, often caused by high rainfall; such rainfall causes formation of the giant sinkholes in the Nakanaï Mountains, on the New Britain island in Papua New Guinea. Powerful underground rivers may form on the contact between limestone and underlying insoluble rock, creating large underground voids.

In such conditions, the largest known sinkholes of the world have formed, like the 662 m Xiaozhai Tiankeng (Chongqing, China), giant sótanos in Querétaro and San Luis Potosí states in Mexico and others.

Unusual processes have formed the enormous sinkholes of Sistema Zacatón in Tamaulipas (Mexico), where more than 20 sinkholes and other karst formations have been shaped by volcanically heated, acidic groundwater. This has produced not only the formation of the deepest water-filled sinkhole in the world—Zacatón—but also unique processes of travertine sedimentation in upper parts of sinkholes, leading to sealing of these sinkholes with travertine lids.

The U.S. state of Florida in North America is known for having frequent sinkhole collapses, especially in the central part of the state. Underlying limestone there is from 15 to 25 million years old. On the fringes of the state, sinkholes are rare or non-existent; limestone there is around 120,000 years old.

The Murge area in southern Italy also has numerous sinkholes. Sinkholes can be formed in retention ponds from large amounts of rain.

On the Arctic seafloor, methane emissions have caused large sinkholes to form.

Human uses
Sinkholes have been used for centuries as disposal sites for various forms of waste. A consequence of this is the pollution of groundwater resources, with serious health implications in such areas.

The Maya civilization sometimes used sinkholes in the Yucatán Peninsula (known as cenotes) as places to deposit precious items and human sacrifices.

When sinkholes are very deep or connected to caves, they may offer challenges for experienced cavers or, when water-filled, divers. Some of the most spectacular are the Zacatón cenote in Mexico (the world's deepest water-filled sinkhole), the Boesmansgat sinkhole in South Africa, Sarisariñama tepuy in Venezuela, the Sótano del Barro in Mexico, and in the town of Mount Gambier, South Australia. Sinkholes that form in coral reefs and islands that collapse to enormous depths are known as blue holes and often become popular diving spots.

Local names
Large and visually unusual sinkholes have been well known to local people since ancient times. Nowadays sinkholes are grouped and named in site-specific or generic names. Some examples of such names are listed below.

 * Aven – In the south of France (this name means pit cave in the Occitan language).
 * Black holes (not to be confused with cosmic black holes) – This term refers to a group of unique, round, water-filled pits in the Bahamas. These formations seem to be dissolved in carbonate mud from above, by the sea water. The dark color of the water is caused by a layer of phototropic microorganisms concentrated in a dense, purple colored layer at 15 to 20 m depth; this layer "swallows" the light. Metabolism in the layer of microorganisms causes heating of the water. One of them is the Black Hole of Andros.
 * Blue holes – This name was initially given to the deep underwater sinkholes of the Bahamas but is often used for any deep water-filled pits formed in carbonate rocks. The name originates from the deep blue color of water in these sinkholes, which is created by the high clarity of the water and the great depth of the sinkholes; only the deep blue color of the visible spectrum can penetrate such depth and return after reflection.
 * Cenotes – This refers to the characteristic water-filled sinkholes in the Yucatán Peninsula, Belize and some other regions. Many cenotes have formed in limestone deposited in shallow seas created by the Chicxulub meteorite's impact.
 * Dolina – Slavic toponym (from Slovene language dòla:"valley" or "dale"). The name is widely used in various slavic regions of Eastern Europe for sinkholes, including Romania.
 * Foiba – Friulan Italian dialect word (from the Latin fŏvea: "pit" or "chasm"). The name, is given to sinkholes in the frontier zone between the Italian region of Friuli-Venezia Giulia, Croatia and Slovenia, in the Karst Plateau.
 * Sótanos – This name is given to several giant pits in several states of Mexico.
 * Tiankengs – These are extremely large sinkholes, typically deeper and wider than 250 m, with mostly vertical walls, most often created by the collapse of caverns. The term means sky holes in Chinese; many of this largest type of sinkhole are located in China.
 * Tomo – This term is used in New Zealand karst country to describe sinkholes.
 * Vrtače – Used in Yugoslavia.

Piping pseudokarst
The 2010 Guatemala City sinkhole formed suddenly in May of that year; torrential rains from Tropical Storm Agatha and a bad drainage system were blamed for its creation. It swallowed a three-story building and a house; it measured approximately 20 m wide and 30 m deep. A similar hole had formed nearby in February 2007.

This large vertical hole is not a true sinkhole, as it did not form via the dissolution of limestone, dolomite, marble, or any other water-soluble rock. Instead, they are examples of "piping pseudokarst", created by the collapse of large cavities that had developed in the weak, crumbly Quaternary volcanic deposits underlying the city. Although weak and crumbly, these volcanic deposits have enough cohesion to allow them to stand in vertical faces and to develop large subterranean voids within them. A process called "soil piping" first created large underground voids, as water from leaking water mains flowed through these volcanic deposits and mechanically washed fine volcanic materials out of them, then progressively eroded and removed coarser materials. Eventually, these underground voids became large enough that their roofs collapsed to create large holes.

Crown hole
A crown hole is subsidence due to subterranean human activity, such as mining and military trenches. Examples have included, instances above World War I trenches in Ypres, Belgium; near mines in Nitra, Slovakia; a limestone quarry in Dudley, England; and above an old gypsum mine in Magheracloone, Ireland.

Notable examples
Some of the largest sinkholes in the world are:

Africa

 * Boesmansgat – South African freshwater sinkhole, approximately 290 m deep.
 * Lake Kashiba – Zambia. About 3.5 ha in area and about 100 m deep.

Asia

 * Blue Hole – Dahab, Egypt. A round sinkhole or blue hole, 130 m deep. It includes an archway leading out to the Red Sea at 60 m, which has been the site for many freediving and scuba attempts, the latter often fatal.
 * Akhayat sinkhole is in Mersin Province, Turkey. Its dimensions are about 150 m in diameter with a maximum depth of 70 m.
 * Well of Barhout – Yemen. A 112 m deep pit cave in Al-Mahara.
 * Bimmah Sinkhole (Hawiyat Najm, the Falling Star Sinkhole, Dibab Sinkhole) – Oman, approximately 30 m deep.
 * The Baatara gorge sinkhole and the Baatara gorge waterfall next to Tannourine in Lebanon
 * Dashiwei Tiankeng in Guangxi, China, is 613 m deep, with vertical walls. At the bottom is an isolated patch of forest with rare species.
 * The Dragon Hole, located south of the Paracel Islands, is the deepest known underwater ocean sinkhole in the world. It is 300.89 m deep.
 * Shaanxi tiankeng cluster, in the Daba Mountains of southern Shaanxi, China, covers an area of nearly 5019 square kilometers with the largest sinkhole being 520 meters in diameter and 320 meters deep.
 * Teiq Sinkhole (Taiq, Teeq, Tayq) in Oman is one of the largest sinkholes in the world by volume: 90000000 m3. Several perennial wadis fall with spectacular waterfalls into this 250 m deep sinkhole.
 * Xiaozhai Tiankeng – Chongqing, China. Double nested sinkhole with vertical walls, 662 m deep.

Caribbean

 * Dean's Blue Hole – Bahamas. The second deepest known sinkhole under the sea, depth 203 m. Popular location for world championships of free diving, as well as recreational diving.

Central America

 * Great Blue Hole – Belize. Spectacular, round sinkhole, 124 m deep. Unusual features are tilted stalactites in great depth, which mark the former orientation of limestone layers when this sinkhole was above sea level.
 * 2007 Guatemala City sinkhole
 * 2010 Guatemala City sinkhole

Europe

 * Hranice Abyss, in the Moravia region of the Czech Republic, is the deepest known underwater cave in the world. The lowest confirmed depth (as of 27 September 2016) is 473 m (404 m below the water level).
 * Maqluba, in Malta is a sinkhole with a surface area of around 4,765 square metres (51,290 sq ft) situated in the village of Qrendi in Malta. The diameter is around 50m, the depth is around 15m, and the perimeter 300m.
 * Pozzo del Merro, near Rome, Italy. At the bottom of an 80 m conical pit, and approximately 400 m deep, it is among the deepest sinkholes in the world (see Sótano del Barro below).
 * Red Lake – Croatia. Approximately 530 m deep pit with nearly vertical walls, contains an approximately 280 – deep lake.
 * Gouffre de Padirac – France. It is 103 m deep, with a diameter of 33 m. Visitors descend 75 m via a lift or a staircase to a lake allowing a boat tour after entering into the cave system which contains a 55 km subterranean river.
 * Vouliagmeni – Greece. The sinkhole of Vouliagmeni is known as "The Devil Well", because it is considered extremely dangerous. Four scuba divers have died in it. Maximum depth of 35.2 m and horizontal penetration of 150 m.
 * Pouldergaderry – Ireland. This sinkhole is located in the townland of Kilderry South near Milltown, County Kerry at 52.13264°N, -9.74594°W. The sinkhole, which is located in an area of karst bedrock, is approximately 80 m in diameter and 30 m deep with many mature trees growing on the floor of the hole. At the level of the surrounding ground, the sinkhole covers an area of approximately 1.3 acres. Its presence is indicated on Ordnance Survey maps dating back to 1829.

Mexico

 * Cave of Swallows – San Luis Potosí. 372 m deep, round sinkhole with overhanging walls.
 * Puebla sinkhole – Santa Maria Zacatepec, Puebla. 400 ft diameter and 50 ft deep, it is still growing . 2021.
 * Sima de las Cotorras – Chiapas. 160 m across, 140 m deep, with thousands of green parakeets and ancient rock paintings.
 * Zacatón – Tamaulipas. Deepest water-filled sinkhole in world, 339 m deep.

United States

 * Amberjack Hole – blue hole located 30 mi off the coast of Sarasota, Florida.
 * Bayou Corne sinkhole – Assumption Parish, Louisiana. About 25 acres in area and 750 ft deep.
 * The Blue Hole – Santa Rosa, New Mexico. The surface entrance is only 80 ft in diameter, it expands to a diameter of 130 ft at the bottom.
 * Daisetta Sinkholes – Daisetta, Texas. Several sinkholes have formed, the most recent in 2008 with a maximum diameter of 620 ft and maximum depth of 150 ft.
 * Devil's Millhopper – Gainesville, Florida. 120 ft deep, 500 ft wide. Twelve springs, some more visible than others, feed a pond at the bottom.
 * Golly Hole or December Giant – Calera, Alabama. Appeared 2 December 1972. Approximately 300 by and 120 ft deep.
 * Grassy Cove – Cumberland County, Tennessee. 13.6 km2 in area and 42.7 m deep, a National Natural Landmark.
 * Green Banana Hole – a blue hole located 50 mi off the coast of Sarasota, Florida.
 * Gypsum Sinkhole – Utah, in Capitol Reef National Park. Nearly 15 m in diameter and approximately 60 m deep.
 * Kingsley Lake – Clay County, Florida. 8.1 km2 in area, 27 m deep and almost perfectly round.
 * Lake Peigneur – New Iberia, Louisiana. Original depth 11 ft, currently 1300 ft at Diamond Crystal Salt Mine collapse.
 * Winter Park Sinkhole – Winter Park, Florida. Appeared 8 May 1981. It was approximately 350 ft wide and 75 ft deep. It was notable as one of the largest recent sinkholes to form in the United States. It is now known as Lake Rose.

Oceania

 * Harwoods Hole – Abel Tasman National Park, New Zealand. 183 m deep.

South America

 * Sima Humboldt – Bolívar, Venezuela. Largest sinkhole in sandstone, 314 m deep, with vertical walls. Unique, isolated forest on bottom.
 * In the western part of Cerro Duida, Venezuela, there is a complex of canyons with sinkholes. Deepest sinkhole is 450 m deep (from lowest rim within canyon); total depth 950 m.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Sinkhole


text:
International Society for Complexity, Information, and Design

The International Society for Complexity, Information, and Design (ISCID) was a creationism advocacy organization that described itself as "a cross-disciplinary professional society that investigates complex systems apart from external programmatic constraints like materialism, naturalism, or reductionism." It was founded and led by figures associated with the intelligent design movement, such as William A. Dembski and Michael Behe.

Overview
The society was launched on 6 December 2001. It was co-founded by William A. Dembski, Micah Sparacio and John Bracht. Dembski served as its executive director. It had about sixty fellows, many of them figures associated with the intelligent design movement and fellows of the Discovery Institute's Center for Science and Culture, including Dembski, Behe, Jonathan Wells, William Lane Craig, and Henry F. Schaefer. Other notable ISCID fellows include philosopher of religion Alvin Plantinga and physics professor and theologian Frank J. Tipler.

ISCID hosted its first online symposium in October 2002, titled "The Teleological Origin of Biological Information."

ISCID described itself as providing "a forum for formulating, testing, and disseminating research on complex systems through critique, peer review, and publication," with an aim "to pursue the theoretical development, empirical application, and philosophical implications of information- and design-theoretic concepts for complex systems."

ISCID maintained an online journal titled Progress in Complexity, Information and Design (PCID). Articles were submitted through its website and could appear in the journal if they had been approved by one of the fellows. Dembski and Tipler believed that this review process was preferable to the process of scholarly peer review commonly used in mainstream journals, citing that peer review "too often degenerates into a vehicle for censoring novel ideas that break with existing frameworks."

ISCID also hosted an online forum called Brainstorms and maintains a copyrighted online user-written Internet encyclopedia called the ISCID Encyclopedia of Science and Philosophy. The society featured online chats with intelligent-design proponents and others sympathetic to the movement or interested in aspects of complex systems. Past chats included people such as Ray Kurzweil, David Chalmers, Stuart Kauffman, Christopher Michael Langan and Robert Wright.

In May 2011 the society's website stated that "ISCID is no longer being managed as an organization". The last issue of PCID was published in November 2005, its essay contests had been discontinued, and the last moderated chat was in 2004. By 2014, its website was no longer online.

PCID peer review controversy
ISCID's journal, Progress in Complexity, Information, and Design has been cited as an example of a journal set up by intelligent design proponents to publish articles promoting intelligent design without a peer review process with sufficient impartiality and rigor. ISCID fellows who comprised PCID ' s reviewers were characterized as "ardent supporters of intelligent design."

ISCID's peer review policy for PCID was based on ISCID Fellow Frank Tipler's article covering what he saw as problems with traditional peer review processes. ISCID required that for articles to be accepted into the archive, they "need to meet basic scholarly standards and be relevant to the study of complex systems." Once in the archive, articles only needed to be approved by a single ISCID Fellow in order to be published. ISCID says that this policy is designed to provide peer review for quality without squelching paradigm changing theories. However, the American Association for the Advancement of Science contended that review processes such as PCID 's were different from the accepted standard of peer review, where "reviewers are experts in the relevant scientific fields who have no conflict of interest with or especially close personal relationships to the authors or requestors."

Fellows
In addition to guiding the society's various programs, fellows served as the editorial advisory board that peer-reviewed the society's journal, PCID.

Partial list of ISCID Fellows: • Michael Behe

• John Angus Campbell

• Robin Collins

• William Lane Craig

• Bernard d'Abrera

• William A. Dembski

• Guillermo Gonzalez

• Bruce L. Gordon

• Muzaffar Iqbal

• Christopher Michael Langan

• Forrest Mims

• Scott Minnich

• Paul Nelson

• Alvin Plantinga

• Henry F. Schaefer, III

• Jeffrey M. Schwartz

• Richard Sternberg

• Frank J. Tipler

• Jonathan Wells


text:
Talk:Nysa (disambiguation)

Nysa and Neisse
To anyone, who might have the idea of moving this article to its German name "Neisse": This article shall remain under its Polish name in accordance with a compromise, which you may view on the Odra talk page. So, please don't move it! -- Cordyph 15:16 Feb 21, 2003 (UTC)

Does anyone have any evidence that the second and third rivers listed here are actually called Neisse in English? I think this page should be about the Neisse of the Oder-Neisse line (which is currently unnecessarily disambiguated as Lusatian Neisse), and that the other two are usually called Nysa in English. --Zundark 10:33, 11 Dec 2003 (UTC)

In my opinion the pronounciation of Nysa in English is very close to pronounciation of German Neisse. That's why the English name of the river is Nysa: the Lusatian Nysa, the Klodzko Nysa, etc -- cc, 22:18, 12 Dec 2003 (UTC)

 * Interesting change of tactics, but equally wrong. It's not just pronounced "Neisse" in English (and native English speakers will know how to pronounce it based on that spelling, not your incorrect spelling), but it's also spelled that way too.  Daniel Quinlan 00:18, Dec 13, 2003 (UTC)

Nysa and Hittite Kanes
Is possible that Nysa, the birth-city of Dionysus was the city Kanesh or Nesa in Eastern Anatolia? Is possible that the etymology of name "Dionysus" is "Deus (the) Nesian" i.e "God the Hittite"?

Note: The real name of the indoeuropean Hittites was "Nesites" or Nesians.

--IonnKorr 12:46, 2 November 2005 (UTC)

 * Many Greeks were sure that the cult of Dionysus arrived in Greece from Anatolia, but Greek concepts of where Nysa was, whether set in Anatolia, or in Libya ('away in the west beside a great ocean'), Ethiopia (Herodotus), or Arabia (Diodorus Siculus), are variable enough to suggest that a magical distant land was intended, perhaps named 'Nysa' to explain the God's unreadable name, as the 'god of Nysa.' Apollodorus seems to be following Pherecydes, who relates how the infant Dionysus, god of the grapevine, was nursed by the rain-nymphs, the Hyades at Nysa. The Anatolian Hittites' name for themselves in their own language ("Nesili") was "Nesi," however.
 * From site:
 * http://www.sciencedaily.com/encyclopedia/dionysus

--IonnKorr 17:01, 3 May 2006 (UTC)

title: Talk:Nysa (disambiguation)


text:
Talk:Pashto

Arabic script unexplicably included in History section
This Arabic script was on the page under the History heading, without explanation.

غزل سوغاتونه ستا له لوري راوړي راشي توره شپه روښانه ستوري راوړي راشي

په ماښام د مخ څراغ و ماته بل کړي په غرمه د زلفو سیوري راوړي راشي

ملغلرې زور وروته ورپرېږدي اوښکې خپل کور ته کمزوري راوړي راشي

په سرو وینو دې لا نه ده سرپه ماته خال دې غشي تر موږ پوري راوړي راشي

زه ترې وغواړم لعلونه ای "درویشه" دوی زما د غزل توري راوړي راشي

--nertzy 10:43, August 17, 2005 (UTC) It's Pashto Writing — Preceding unsigned comment added by 69.27.68.247 (talk • contribs) 16:34, 11 April 2008

In an article in a book dealing with the World's major Languages on Pashtu I saw mention that Pashtu actually has two oblique cases, one of which is essentially a prepositional case as it only occurs after certain prepositions. It is not mentioned in this article. Could anyone comment on this af:Gebruiker:Jcwf — Preceding unsigned comment added by 152.1.193.141 (talk • contribs) 20:57, 5 January 2006

This is in fact true, but its use varies widely from dialect to dialect. Also, it can be plausibly argued that the case of which you speak is a suffixed postposition in many instances: "la kora (from the house) = *la kor na. In instances where the noun ends on a vowel, the full postposition is used: "la koro na (from the houses)". But also the same morphological marker can also denote a collective noun, like "1 dollar; 2 dollara; tso dollara? (how many dollars?)". — Preceding unsigned comment added by Channa.web (talk • contribs) 18:44, 9 March 2007

Pashto Phonology
Southwest (Kandahari) is the most conservative in phonology because it retains a four way distinction with regards to these four phonemes (ts, dz, š., ž.) Pashto is a phonologically rich language with regards to consonants...Kandahari dialect: p, b, t, d, t., d., k, g, q, ?, ts, dz, č, j, f, s, z, š, ž, š., ž., x, ġ, h, l, r, r., m, n, ñ, w, j (Non-IPA)

Northeast merged: ts, dz with s, z ;š., ž. with x and ġ Southeast merged: š., ž. with š, ž Northwest merged: ts, dz with s, z; ġ with y

Whatever the Proto-Pashto phonemes were, Southwest must be conservative because it retains all four phonemes with no mergers. Imperial78 — Preceding undated comment added 08:29, 31 January 2006

Unofficial and amateurish
The tabular representation of Pashto dialects as well as the so-called Roman alphabet are among the numerous private and amateur offerings in this regard. No "official" or academically approved/sanctioned work by any authority in this regard exists. Neither are any sources cited for these. Casual visitors to this page will likely construe these alphabets and dialectical representations as being standard, which they are not. — Preceding unsigned comment added by 58.27.145.123 (talk • contribs) 21:43, 11 January 2009

Examples

 * Note - The following transliterations represent the southern dialect.

Examples of intransitive sentence forms using the verb "tlël" (to go):

Command:

 * Wë šawanxi ta xa! (pronounce xa as 'dza')
 * (you sing.) Go to school!

Present:

 * (Zë) wë šawanxi ta xëm.
 * I go to school.

Present Perfect:

 * (Zë) wë šawanxi ta tlëlai yëm.
 * I have gone to school.

Past:

 * (Zë) wë šawanxi ta wlâřëm.
 * I went to school.

Past Perfect:

 * (Zë) wë šawanxi ta tlëlai wëm.
 * I had gone to school.

Past Progressive:

 * (Zë) wë šawanxi ta tlëm.
 * I was being going to school. meaning I used to go to school.

Subjunctive:

 * Cheh zë wë šawanxi ta tlëlai.
 * I wish I go to school.

Examples of transitive sentence forms using the verb "ķwařël" (to eat):

Command:

 * Panir ķwrëi!
 * (you plur.) Eat cheese!

Present:

 * Dai panir ķwri.
 * He eats cheese.

Present Perfect:
 * Dë panir ķwařëlai dae.
 * He has eaten cheese.

Past:

 * Dë panir wuķwařë.
 * He ate cheese.

Past Perfect:

 * Dë panir ķwařëlai wë.
 * He had eaten cheese.

Past Progressive:

 * Dë panir ķwařë.
 * He was being eating cheese. meaning He used to eat cheese.

Subjunctive:

 * Ka dë panir ķwařëlai.
 * If he eat cheese.

Questions:
 * Cë nameže? or Stâ num cë dae? (What is your name?)

 * Çereh or çerta xe? (Where are you going?) — Preceding unsigned comment added by Azalea pomp (talk • contribs) 07:32, 27 March 2009

Months and Calender
It is written that the Pashtuns use the Vikrami Calendar. This is not true, the majority of Pashtuns live in Afghanistan and Pakistan, in both countries the Vikrami Calendar isn't used. The Islamic calendars are used in both Afghanistan and Pakistan, and in Pakistan the Gregorian calendar is used as well. In any case, the Vikrami Calendar is not used and has never been widely used at all. As far as I know, Pashtuns even have their own calendar, which is used in rural places. It is mainly the Islamic calendars though. Zarang23 (talk) 22:06, 3 July 2024 (UTC)

title: Talk:Pashto


text:
User:Krenard~enwiki

If you do not stop uploading documents action will have to be taken. --snoyes 15:31 Feb 21, 2003 (UTC)

title: User:Krenard~enwiki