The intervals between geyser eruptions depend on a delicate balance of underground factors, such as heat and water supply, and interactions with surrounding geysers. Some geysers are highly predictable, with intervals between eruptions varying only slightly. The predictability of these geysers offer earth scientists a unique opportunity to investigate what may influence their eruptive activity, and to apply that information to rare and unpredictable types of eruptions, such as those from volcanoes.
http://www.sciencedaily.com/releases/2014/05/140507114805.htm