Perpustakaan Digital ITB

Geothermal heat discharge rate (HDR) is the amount of the heat emitted from the land surface in the geothermal field, where the heat is transferred in many ways such as conduction, convection and radiation. It is not only the index which indicates the scale of the geothermal area but also the value which gives the boundary conditions of numerical models (Ehara and Noda, 2014). Several researches had been conducted to observe the HDR in geothermal areas. Although the HDR is often measured by airborne or field measurement, it is difficult to observe the many weather parameters near active volcanoes due to the cost for the study and the unstable areas around active manifestations. Satellite remote sensing techniques would be an effective method to solve these problems and to enable a convenient analysis. This study has two objectives. The first objective is to establish the method of HDR estimation. RHF (Radiative heat flux) is estimated using remote sensing technique, and secondly HDR data is obtained through field surveys or existing data (previous surveys). Finally, the relationship between RHF and HDR using both the data is considered. In addition to the ratio of RHF and HDR, this study also discuss the variation of the relationship between both the data to the manifestation type and the size of a study area. RHF was less than 5-10 % of HDR in most cases. The relationship between RHF and HDR can be classified by the manifestation type. If a manifestation with much vapor content is the main manifestation in the interest area, the proportion of the RHF to the HDR would be less than 5%. If steaming ground is the main manifestation in the interest area, the ratio would be 5-25%. The method was established to estimate HDR by only using the satellite image analysis. This new method can show the approximate HDR data and the increase/decrease trend in the consideration of the limitations. The second objective is the application to volcano monitoring. It is necessary to observe an identical volcano for a long time from the view of not only geothermal exploration but also disaster prevention. However, long time and continuous observation is difficult to carry out near volcanos. Then this study tries to analysis a number of images and observe a study area over a long time. In addition, the images obtained near the eruption to observe the changes before and after the eruption are also analyzed. The time series analysis of satellite images could capture the change in the NDVI (Normalized Difference Vegetation Index), the LST (Land surface temperature) and the RHF before and after the eruption. This method could be applied for volcano monitoring.