Tunguska Basin, c.400,000 sq mi (1,036,000 sq km), Krasnoyarsk Territory and Sakha Republic, E central Siberian Russia, between the Yenisei and Lena rivers. It has a huge untapped coal reserve. The main settlements there are Norilsk, Igarka, and Yeniseisk (all in Krasnoyarsk Territory); the basin is crossed by the Tunguska rivers. On June 30, 1908, a section of the basin near the Stony Tunguska River was the scene of the Tunguska Event, a huge explosion that flattened hundreds of square miles of forest. It may have resulted from the catastrophic breakup of a stony asteroid about 100 ft (30 m) in diameter 5 mi (8 km) above the earth's surface.