Exploring and monitoring geothermal and volcanic activities using Satellite Thermal Infrared data in Northern Taiwan

• Main Authors: Hai-Po Chan, 詹海柏
• Other Authors: Chung-Pai Chang
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/d9b8un

博士 === 國立中央大學 === 地球科學學系 === 106 === Abstract Geothermal energy is an increasingly important component of renewable and green energy in the globe. A prerequisite for geothermal energy development is to acquire the local and regional geothermal prospects. Existing geophysical methods of monitoring or exploring the geothermal resource are usually limited to the scope of prospecting because of the operation cost and site reachability in the field. Thus monitoring or explorations in a large-scale area such as the surface temperature and the thermal anomaly primarily rely on satellite thermal infrared imagery. This research aims to apply and integrate Thermal Infrared (TIR) Remote Sensing technology with existing geophysical methods for the geothermal exploration and volcanic monitoring in northern Taiwan. Two hot potential sites of geothermal energy in Taiwan have been studied in this research. Namely, 1) Ilan Plain of northeastern Taiwan; 2) Tatun Volcanic Group (TVG) of northern Taiwan. Thermal Infrared Remote Sensing technology has been applied for both sites. Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) imagery is used to retrieve the Land Surface Temperature (LST) in Ilan Plain and TVG. Accuracy assessment of satellite derived LST is conducted by comparing with the air temperature data from 11 permanent meteorological stations. The correlation coefficient of linear regression between air temperature and LST retrieval is 0.76. The MODIS LST product is used for the cross validation of Landsat derived LSTs. Furthermore, Landsat ETM+ multi-temporal brightness temperature imagery from 1999 to 2016 for the verification of the LST anomaly results were performed. Results from the application of TIR remote sensing in Ilan Plain indicate that thermal anomaly areas appear spatially correlating with the development of faulted structure. Selected geothermal anomaly areas are validated in detail by the field investigation of hot springs and geothermal drillings. It implies that occurrences of hot springs and geothermal drillings are in good agreement with anomaly areas. In addition, the significant low-resistivity zones observed in the resistivity sections are echoed with the LST profiles when compared with in the Chingshui geothermal field. For the application of TIR remote sensing in TVG, Landsat 7 thermal infrared imagery was used to retrieve the LST and Radiative Heat Flux (RHF), and MODIS LST products were analyzed for the Jinshan fault area in TVG. Detected LST anomaly areas are validated by the field investigation of hot springs and fumaroles. It implies that occurrences of hot springs and fumaroles conform to anomaly areas. The overall temperature in E-W ridge is hotter than the SW-NE ridge in TVG. Thermal anomaly patterns also indicate that distributions of higher LST areas appear correlating with the development of Jinshan fault. Besides, Hilbert Huang Transform (HHT) was adopted for analyzing MODIS LST time series (2002-2016) in Jinshan fault area. Possible related physical processes underneath of Ensemble Empirical Mode Decomposition (EEMD) components which are the key parts of HHT were also discussed. The inference that LST component with average period around a month (EEMD component 1, i.e. C1) has irregular spikes which is possibly associated with earthquakes in TVG has been investigated in detail. Finally, HHT comparison analysis with three active volcanoes in Philippines and Indonesia is performed for attempting to assess the eruption potential of TVG. The effectiveness of satellite thermal infrared remote sensing in retrieval of LST using Landsat images was demonstrated. And the usefulness of HHT data analysis method on MODIS LST time series was also presented. Despite limited to detecting the surficial and the shallow buried geothermal resources, the work in Ilan Plain and TVG suggests that TIR Remote Sensing is a valuable tool for mapping and quantifying surface features to expand the understanding and enhance the knowledge of the geothermal and volcanic areas with less time-consuming and high cost-efficiency.