Bolshoy (Big) is one of the largest geysers in the Valley, and also the most convenient for observation and study. It is located near the visitor center of the Kronotsky Reserve, and very well visible from the observation point closest to the geyser. The edifice of the Bolshoy geyser stands out by its size and geyserite coating. Its crater has size of 1x2.5 m, and according to video footage the channel is 3.5 m deep (Belousov et al., 2013). During fountaining the water is thrown away from the channel as a continuous powerful stream with volume about 16 m3 (Droznin, 1998) and weakens gradually, so it is difficult to determine the end of the eruption. Two levels of periodicity are often noted: 100-130 minutes and 70-90 minutes. Such deviation in the regime can be connected with significant precipitation (50-140 mm) and / or wind up to 10-20 m/s (archives of the Sugrobovs and Droznin V.A.). Until 2007, the Bolshoy geyser was 40 m from the Geysernaya River and 13 m above its level. After the landslide of June 3, 2007, its channel was flooded by water from dammed lake and was at the depth about 2 m, the geyser did not erupt, and its activity came out in the form of "waves" and gas bubbles on the surface of the lake. At the beginning of September 2007 the lake level dropped and on September 12, the first eruption after the flooding was noted. For about 1 year a cold lake water poured into the griffin after the eruption. The eruptions became less powerful (about 10-12 m high) and resembled the huge bubbling. In 2008-2013, the geyser period was about 1 hour. After the collapse in the headwater of Geysernaya River on January 4, 2014, the dammed lake was filled with the deposits of the 2014 lahar, but the Bolshoy geyser was not damaged. Now the geyser is located at a height of 3 m above the river level. Bolshoy is a rather stable geyser and throughout the history of observation its period changed from 1 to 2 hours.
References
Belousov A., Belousova M., Nechayev A. Video observations inside conduits of erupting geysers in Kamchatka, Russia, and their geological framework: Implications for the geyser mechanism // Geology. 2013. Vol. 41. № 4. P. 387-390.  Droznin V.A. Excursion to the Kamchatka Geysers // The Journal of the Geyser Observation and Study Association. 1998. Vol. VI. P. 234-247. Леонов А.В. Каталог гейзеров Кроноцкого заповедника. Долина гейзеров и кальдера вулкана Узон: история и современность. М.: Изд-во ООО «Реарт». 2017. 384 с. Устинова Т.И. Камчатские гейзеры / Отв. ред. Рихтер Г.Д., Никольская В.В. М.: Географгиз. 1955. 119 с.  |
