1992 hydrothermal explosion near drill well

An exploration well into a zone of hot water 4.5 km SW of the summit of Baransky Volcano (in the Kipyaschaya River valley) was drilled in the summer of 1991. Drilling was temporarily halted at Baransky in early August, but no casing was installed. Two weeks later, a hydrothermal explosion occurred 50 m upslope, forming a crater >10 m in diameter.
A mixture of vapor, water, and a large quantity of rock fragments was erupted for several days, destroying vegetation within 50 m. The explosion was believed to have occurred when hot water moved up the borehole after drilling ceased, and escaped through its uncased walls into a permeable fissured zone near the surface.
Source: GVP / Smithsonian monthly reports