The Kola Superdeep Borehole SG-3 (: Кольская сверхглубокая скважина СГ-3, : Kol'skaya sverkhglubokaya skvazhina SG-3) is the on Earth (since 1979), whic. .
Drilling at Kola SG-3 began on 24 May 1970 using the -4E, a serial drilling rig used for drilling . The rig was slightly modified to be able to reach a 7,000-metre (23,000 ft) depth. In 1974, the new purpos. .
The stated areas of study of the Kola Superdeep Borehole were the deep structure of the , discontinuities and the thermal regime in the Earth's crust, the physical and chemical compositio. .
The drilling ended in 1995 due to a lack of funding. The scientific team was transferred to the federal state unitary subsidiary enterprise "Kola Superdeep," downsized, and given the new task of thoroughly studying th.
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