Russian military engineers carry out controlled explosions to ‘move a mountain’ blocking the Bureya River in Siberia’s Khabarovsk Region on Friday, after a landslide damned the waterway.
The 165m (550ft) mound was caused by a landslide at the beginning of December.
Geologists fear that use of explosives will cause a second giant rockfall into the Bureya.
Moving the block has become urgent because four villages and the Baikal Amur Mainline rail link are threatened with flooding.
While further downstream, a key hydroelectric reservoir is deprived of water.
Military engineers and sappers have been tackling the jam by carrying out a series of explosions.
The Russian Ministry of Defence has sent 500 personnel, 43 units of specialist equipment and six army helicopters to work on mission.
The final phase of the works is due to be completed on February 18.