Grot (Grotto) is the most mystical geyser in the Valley (Leonov, 2017). It is located at the right corner of the Stained-Glass wall (Vitrazh), in a small cave shrouded in clouds of steam. It was first described and named by T.I. Ustinova (1955): “Large periodic spring, the Grot, goes deep into the slope, where water, poorly distinguishable in clouds of steam, splashes in the elongated pool about 7 m long and 1–1.5 m wide. Powerful waves periodically pour out from the pool.” The main activity of the Grot are periodic outpourings, and a channel (“Grot drain”) was formed in the right part of Vitrazh, it is clearly visible from afar due to its light yellow color. In 1975-1991, using a Valdai level gauge installed in the Grot drain, the geyser’s periodicity was determined by its outpourings: 30-50 min (data from the Sugrobovs). Stories about its eruptions were considered as a fiction until several such eruptions were photographed and filmed at summer 1991 during an American expedition to the Valley of Geysers (Bryan et al., 1991). The expedition members directly observed 44 eruptions of the Grot. This “anomalous” activity was man-made (which the Americans did not suspect): before their visit, the inspector of the Kronotsky Nature Reserve V.A. Nikolaenko dug up the drain from the Grot's bath, lowering the water level in it by 15-20 cm (Nechaev, 2007). The powerful geyser made a huge impression on foreign guests: "No geyser on Earth can compare with the Grot in size and the beauty of its location on a steep slope." After the Americans left, the drain was returned to its original state (filled with stones), since frequent and powerful eruptions of the Grot threatened to destroy the appearance of the Virazh. Since then, some people have managed to see Grot eruptions, and it was recognized as a geyser with very rare, non-periodic eruptions. An eruption of the Grot is a grandiose spectacle. An inclined, almost horizontal stream of boiling water roars from the cave across the entire Vitrazh, washing away the clay and geyserite on its opposite edge. The length of the jet is estimated up to 65 m. Grot can erupt in series up to 7 times in a row with breaks of 2-3 minutes, each eruption lasting 20-30 seconds. During the eruption, a powerful stream of boiling water rolls down the slope in a cascade of small waterfalls. The water flow of the geyser, calculated by the rise in the river level, was equal to 160 l/s. The approximate volume of the chamber after its complete emptying was 30 m³. According to these parameters, the Grot is the biggest geyser in the Valley (Leonov, 2017).
References
Bryan S.T., Hobart J., Warnock B., Rinehart J.S., Fenimore M., Colvin B. The Geysers of 'The Valley of Geysers'. A special report of GOSA Transactions. USA, California: B&J Printing. 1991. 60 p.  Леонов А.В. Каталог гейзеров Кроноцкого заповедника. Долина гейзеров и кальдера вулкана Узон: история и современность. М.: Изд-во ООО «Реарт». 2017. 384 с. Нечаев А. Долина гейзеров. М.: Логата. 2007. 166 с. Устинова Т.И. Камчатские гейзеры / Отв. ред. Рихтер Г.Д., Никольская В.В. М.: Географгиз. 1955. 119 с.  |
