In 1885 a part of the southen collapse due to the pressure of the lava in the Semeru
As far as we can conclude from the volcanial history of the G.Kelut, after each out burst a craterlake was formed (Potrait of the Craterlake among others in 'Geweldige Natuurkrachten' by Vissering in J.v.h. Minjnwezen 1907, Verhandeling Hugo Cool and a.m).
In the night of May 19th to the 20th, 1919 the nature powers again have shown their everything destructing violence. The contents of the craterlake of the G.Kelut was suddenly ejected over the craterwalls.