Measuring pressure in the source region for geysers, Geyser Valley, Kamchatka

Liquid water and steam that erupt at geysers are provided from deeper reservoirs, whose location, geometry and pressure are in general poorly known. Here we report measurements at two geysers from a field experiment in Geyser Valley, Kamchatka, designed to measure pressure in the reservoir providing water to the geysers. Water level in the geyser conduit was controlled, and the recharge to the geyser conduit was measured by monitoring the discharge needed to maintain the controlled water level. Recharge is not constant, but depends on water level in the geyser. From the relationship between water level in the conduit and recharge to the conduit, we can estimate the hydraulic head in the reservoir that supplies water to the geyser. Hydraulic head in the two studied reservoirs is within a couple of meters of the elevation of the geyser vents and the adjacent rivers. Pressures in the reservoirs are low enough that the reservoirs should not be prone to hydrothermal explosions, and explain why flooding of geysers in Geyser Valley terminated their eruptions.