All of the following disasters happened in Russia recently EXCEPT ______. [origi

Russia is observing a national day of mourning in memory of at least 177 people killed in the past few days in three disasters — a mine explosion, a nursing home fire and a plane crash.
     Flags are flying at half-mast today across Russia as the nation struggles to come to terms with the large loss of life, which investigators say could have been avoided if proper safety regulations had been addressed. In Kemerova in central Siberia, the search is still on for three coalminers missing following Monday’s methane gas explosion that killed more than 100 people. It is Russia’s worst mining disaster since the collapse of the Soviet Union.