The 1818 Giétro Glacier catastrophe, which led to a lake outburst flood, is one of the most famous and most disastrous historical cases in the Swiss Alps.

The Giétro Glacier lies on the northern side of the Pennine Alps in the Swiss canton of Valais.

[1] The glacier is fed by the snows of Mont Blanc de Cheilon (3,870 m) and La Ruinette (3,875 m).

On the lower part, the glacier reaches a steepness of 40% forming a large number of crevasses.

After an increase of the glacier during the "Year Without a Summer", an ice cone started to form in 1816 in the valley.

[2] 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 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.

[2] Only two men stayed in place; Venetz warned the inhabitants of the valley of the danger.

A group of British tourists and a drawer from Lausanne visited the place with Venetz.