After an increase of the glacier during the " Year Without a Summer " , an ice cone started to form in 1816 in the valley . It was created by the accumulation of the falling seracs of the terminus . A lake was formed but it emptied on 27 May 1817 without causing any fatalities . In April 1818 the lake measured about 2 km in length . On 10 May 1818 , the engineer Ignaz Venetz was called by the canton . To stop the rapid rise of waters , he decided to drill a hole through the ice . The work began one day later . A tunnel was drilled from the two sides , about 20 metres above the level of the lake . An avalanche of ice occurred on 18 May but without any casualties . A secondary tunnel was then drilled for safety reasons . A week later the level of the lake reached 10 metres below the tunnel . On 27 May an enormous piece of ice detached itself from the cone in the lake and floated to the surface while making terrible noise ; everybody escaped . They went back to work two days later . The 198 metre-long hole was completed on 4 June . Other large pieces of ice detached from the cone and floated back . The waters finally reached the level of the hole on 13 June , 22:00 . They continued to rise until 14 June , when the level of the lake began to fall because of the erosion of the hole by the waterfall . Some water also ran out from the base of the cone . Only two men stayed in place ; Venetz warned the inhabitants of the valley of the danger . On the morning of 16 June , terrible noises and violent detonations were heard . The cone began to crack . A group of British tourists and a drawer from Lausanne visited the place with Venetz . In the afternoon , Venetz and the workers escaped to the heights of Fionnay
Year Without a Summer
Year Without a Summer
Giétro Glacier