Calorimetry and Hydrothermal Eruptions, Waimangu Hydrothermal Field, 1971-1990

Abstract

Application of and energy balance equations for a water body allow the vented and energy of the two crater lakes at Waimangu to be calculated. The ratio of vented energy to vented is the enthalpy of the fluid entering the lake. At Frying Pan Lake the mean annual discharged is 121 x and energy 8.87 x J. The mean annual enthalpy is 749 + 19 representing a vent temperature of 177?C. At Inferno Crater Lake the mean annual vented mass is 50.6 x and energy 4.1 x J. The average annual enthalpy is 1197 117 During the 19year monitoring period examined, seven hydrothermal disturbances have occurred within the Waimangu hydrothermal system; some were subtle while others were catastrophic producing large surface changes. The long term trends indicate the total heat flow from Waimangu has stabilised to the physical conditions created by the 1886 volcanic eruption. This stable signature also indicates a steady state in processes associated with Tarawera Volcanic Complex.