 The first well-documented surge occurred on July 3, 1902, in the midst of an unusually hot summer, when the mean temperature was 2.7 °С higher than normal.A series of heavy rains occurred in June and early July, filling the river basins with rain and melt water and by the middle of June, a tongue of the Kolka glacier was on the move.Loud crackling was heard in the nearby settlements and, at times, the Genaldon river was turned into a stream of black mud.