Calorimetry of Inferno Crater Lake, Waimangu

Abstract

A description is presented of data reduction methods used to maximise the extraction of information detail from records obtained by the N.Z. Geological Survey monitoring system at Waimangu, with particular emphasis on the data from Inferno Crater Lake. The computer programs have also been adapted to reduce data acquired from time to time by complementary monitoring procedures at Inferno Crater Lake devised in conjunction with research projects by personnel at the Physics Department, University of Auckland. An "Energy Budget Program" has been developed to analyse the data and provide an interpretation of the monitored changes in terms of variations in physical parameters, particularly the enthalpy of the fluids involved. Indeed the program has provided an approximate value of 800 J/g for the vented fluid enthalpy during one of the stages of lake level movement. This is reasonably consistent with the value of 876 J/g, obtained by K. M. Wilson for the enthalpy of hydrothermal fluid entering neighbouring Fryind Pan Lake. The program has also provided a glimpse of the thermodynamic states occurring within the Inferno Crater Lake vent(s). Since simultaneous recording of some 13 parameters is required, and since the study has so far given only one 25 day period when instrumental malfunction did not occur, a complete analysis has been possible so far for only a disappointingly small interval of records.