Climate-driven variations in geothermal activity in the northern Kenya rift valley

HIGH-TEMPERATURE continental geothermal systems are primarily associated with volcanic activity at plate margins 1 . It has long been known that the activity of these geothermal systems is intermittent, and this is generally attributed to the effect of magmatic intrusions or fault motions. Recently, however, it has also been recognized 2–4 that surface-water hydrology and climate variations can influence the evolution of individual silicic caldera-hosted geothermal systems, although it is difficult to judge the general importance of such effects in controlling the long-term behaviour of continental geothermal systems. Here we report uranium-series ages for the hydrothermal deposits of past geothermal activity from several Quaternary volcanic centres in the northern Kenya rift valley. We find that the ages correspond well to periods of high lake level within the rift, suggesting that the elevated water table and increased availability of meteoric water associated with more humid climates can promote greater transfer of heat and mass from deep, long-lived heat sources to the surface.