1.   Among unique building problems was the need to bridge the Neva River where it runs underground and to cope with subterranean water.

2.   In recent years, and for unknown reasons, the level of subterranean waters in Moscow has steadily risen.

3.   Subterranean water reserves, by contrast, are steadily shrinking as the demands of two fast-growing societies outpace natural replenishment by rivers and rainfall.

4.   In addition, local irrigation systems pumping out subterranean water rendered the earth looser, endangering the stability of walls and causing rising damp.

5.   Previous reports said the disaster happened when explosions destroyed underground terrain separating the tin mine from a body of subterranean water, causing extensive flooding.

6.   Subterranean water reservoirs in the northern Gaza Strip and the centre of the West Bank now have Israeli settlement blocs built next to them.