Monitoring heat flow before and after eruption of Kuju fumaroles in 1995 using Landsat TIR images

Abstract

The Kuju fumaroles in central Kyushu, Japan began to erupt as phreatic in nature on 11 October 1995. To infer the thermal activity, main objectives were to monitor the radiative heat flux (RHF) before and after eruption of Kuju fumaroles in 1995 using 4 sets of Landsat TM thermal infrared data from 1990 to 1996; and to calculate and monitor the heat discharge rate (HDR) after multiplying RHF using a relationship coefficient between RHF and HDR, derived from two previous studies. The RHF was estimated by using the Stefan–Boltzmann equation for heat flow where we applied satellite image-derived spectral emissivity and land surface temperature. An increasing trend of total radiant heat flux was obtained of about 22–39 MW before the Kuju fumaroles eruption from 1990 to 1994 and a declining trend total RHF of about 37–11 MW after eruption from 1995 to 1996. RHF was strongly correlated with land surface temperature (LST) above ambient in our study. Spatial distribution of RHF also showed a similar trend of total RHF. After using this relationship coefficient, we obtained the HDR from our study area about 144.64, 249.74, 239.67 and 68.54 MW in 1990, 1994, 1995 and 1996, respectively. The HDR was much higher before eruption in October 11, 1995 than that of after the eruption in our study. Fumaroles area also showed an abrupt increase of bared land and no vegetation just after eruption within the thematic map in 1995. Statistics of LST and RHF also showed evidences of heat loss activity before and after eruption in 1995. In conclusion, we infer from this study that Landsat TM thermal infrared images are fully competent to monitor thermal activity from any active volcano fumaroles for future eruption.