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| | 講演要旨(英文) | | The locating of the subsurface permeable fracture zones and/or the faults is important for the developing or evaluating geothermal resources. However, due to the social conditions or the complicated terrain in/around geothermal site, the conventional reflection imaging method is difficult to be applied in many cases and the passive imaging can be a solution to overcome these problems. The nature microearthquake sources can be recorded with the geophones distributed within the geothermal area together with the reflected signals from the fracture zones. To obtain the imaging results, the whole procedure is introduced in this work. Based on the special input data acquired from polarization analysis of three-component sensor signals, the imaging problems are mainly discussed with the sparse array idea. A coherence factor as a weighting factor for migration is introduced for the imaging processing, which is aimed for reducing the artifacts caused by the limited number of the sensors. With synthetic data, it is demonstrated that it is possible to image the large-scale targets with limited numbers of the sensors/source events and some key issues for imaging are discussed. This work induced a good way for further investigation of the geothermal field with relatively low cost and simple application. |
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