Speleothem fall (an example of a sudden stalactite collapse in Škocjanske Jame)
Andrej Kranjc - (28/1,1999)
On March 2 or 3, 1999 a stalactite fell from the roof in Velika Dvorana (Tiha Jama, Škocjanske Jame). This was a cave shield or palette developed on the ceiling, 17 m above the floor. Stalactites up to 2 m long were hanging on the underside of the shield. The collapsed stalactite mass weighed about 2500 kg. On the floor it split into some large (up to 300 kg) and many smaller pieces. The author thinks that bulk fell off as it reached its critical weight. The speleothem type called "shield" is extremely fragile and not well fixed at its base. In the place where this shield developed there is a strong (up to one l/min) inflow of saturated water and it has been estimated up to 2,5 kg of flowstone/year could be deposited. In Škocjanske Jame active shield-like stalactites mostly have fallen from the roof in the places where they are fed by saturated water. However, in a human timescale such events are extremely rare.