What causes a geyser to erupt?
The science of geyser eruptions was worked out by none other than Robert Bunsen, he of burner fame. Actually Bunsen did not invent the burner but did improve upon existing equipment by showing that mixing the combustible gas with just the right amount of air led to a high temperature nonluminous flame. Such a flame was very useful in the development of Bunsen’s most famous discovery, the spectroscope. In collaboration with physicist Gustav Kirchoff, Bunsen designed an instrument that would pass the light emitted from a sample heated by his burner through a prism. The “spectrum” of light produced was found to be characteristic of the element found in the sample. Before long Kirchoff and Bunsen had identified cesium and rubidium as new elements and paved the way to the identification of thallium, indium, gallium, scandium by others through spectroscopy.
In 1845, during his tenure as Professor of chemistry at Marsburg University, Bunsen was invited by the Danish government on a geological trip to Iceland following the eruption of Mount Hekla. He had a lifelong interest in geology and used the occasion to study the gases released from volcanoes and performed analyses on volcanic rocks. The chemist also became interested in Iceland’s abundant geysers, especially The Great Geysir that propelled water to a height of some fifty meters. Bunsen hypothesized that eruption occurred when a column of underground water was heated around its middle by volcanic activity. In the true spirit of science, Bunsen constructed an artificial geyser in the laboratory consisting of a basin of water and a long tube filled with water extending into it. He heated the tube at various points and showed that it was when the water in the middle reached its boiling point that an eruption occurred just like in a natural geyser.