The approximate length of time between earthquakes in a specific seismically active area.
(from the article `hydrologic sciences`) ...or over a catchment area. The frequency at which a rainfall of a certain volume occurs within a certain period is also important to hydrologic ...
recurrence interval. The average time span between large earthquakes at a particular site. Also termed return period.
The average time period that separates natural events of a specific magnitude. For example, floods of a specific stream discharge level.