Implosion is a process in which objects are destroyed by collapsing (or being squeezed in) on themselves. The opposite of explosion, implosion concentrates matter and energy. True implosion usually involves a difference between internal (lower) and external (higher) pressure, or inward and outward forces, that is so large that the structure collapses inward into itself.[citation needed] An example of implosion is a submarine being crushed from the outside by the hydrostatic pressure of the surrounding water. In the controlled demolition industry, building implosion is the strategic placing of explosive material and timing of its detonation so that a structure collapses on itself in a matter of seconds, minimizing the physical damage to its immediate surroundings. Despite its terminology, building implosion also includes the controlled demolition of other structures, such as bridges, smokestacks, towers, and tunnels. Building implosion (which reduces to seconds a process which could take months or years to achieve by other methods) typically occurs in urban areas and often involves large landmark structures The actual use of the term "implosion" to refer to the destruction of a building is a misnomer. This had been stated of the destruction of 1515 Tower in West Palm Beach, Florida. "What happens is, you use explosive materials in critical structural connections to allow gravity to bring it down collapse collapsed collapsing destroy destroyed destruct destruction 911 wtc twin tower towers bin laden new york city terrorist terrorism debunked debunking debunk conspiracy theory theories taliban al qaeda iraq war terrorists inside job jobs blow blows blown up middle east wars zionism zion zionist zionists extreme falls fallen exploding exploded explosion explosions bomb bombs detonates detonate detonated united states america nyc device weapon weapons mass nuclear bombing bombings fire fires The term building implosion can be misleading to laymen: the technique is not a true implosion phenomenon. A true implosion usually involves a difference between internal (lower) and external (higher) pressure, or inward and outward forces, that is so large that the structure collapses inward into itself. In contrast, building implosion techniques do not rely on the difference between internal and external pressure to collapse a structure. Instead, the technique weakens or removes critical supports so that the building can no longer withstand the force of gravity and falls under its own weight. Numerous small explosives, strategically placed within the structure, are used to catalyze the collapse. Nitroglycerin, dynamite, or other explosives are used to shatter reinforced concrete supports. Linear shaped charges are used to sever steel supports. These explosives are progressively detonated on supports throughout the structure. Then, explosives on the lower floors initiate the controlled collapse. A simple structure like a chimney can be prepared for demolition in less than a day. Larger or more complex structures can take up to six months of preparation to remove internal walls and wrap columns with fabric and fencing before firing the explosives. Historical overview Demolition by controlled explosion in Buffalo, New York As part of the demolition industry, the history of building implosion is tied to the development of explosives technology. One of the earliest documented attempts at building implosion was the 1773 razing of Holy Trinity Cathedral in Waterford, Ireland with 150 pounds of gunpowder, a huge amount of explosives at the time. The use of low velocity explosive produced a deafening explosion that instantly reduced the building to rubble. The late 19th Century saw the erection of—and ultimately the need to demolish—the first skyscrapers, which had more complicated structures allowing greater heights. This led to other considerations in the explosive demolition of buildings, such as worker and spectator safety and limiting collateral damage. Benefiting from the availability of dynamite, a high-velocity explosive based on a stabilized form of nitroglycerine, and borrowing from techniques used in rock-blasting, such as staggered detonation of several small charges, building demolition edged toward efficient building implosion. Following World War II, European demolition experts faced with massive reconstruction projects in dense urban areas gathered practical knowledge and experience for bringing down large structures without harming adjacent properties. This led to the emergence of a demolition industry that grew and matured during the latter half of the twentieth century. At the same time, the development of more efficient high-velocity explosives such as RDX and non-electrical firing systems combined to make this a period of time in which the building implosion technique was extensively used. Meanwhile, public interest in the spectacle of controlled building explosion also grew

• published: 31 Jan 2014
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