| Abstract |
Attenuation is the physical parameters of rock that can reflect the subsurface geological conditions. We conducted attenuation tomographic imaging in the geothermal field by using the Microearthquake (MEQ) data in the form of attenuation operator, t*. We applied a method of spectral fitting to invert for the t* value. For the attenuation tomographic inversion, we used the initial 3-D velocity model from the previous study in the region. Our study results show that the value of Qp, Qs and Qp/Qs ratio in the geothermal field is an important parameter for interpreting the subsurface structure. The geothermal field in this study lies between several active and dormant volcanoes in west Java Province, Indonesia. This geothermal field already produces electricity of more than 220 MWe. The hydraulic stimulation has been carried out from the end of 2007 until the beginning of 2008 in order to get an understanding about the orientation of weak or fractures zones, so that the strategy of exploration and well targeting could be estimated. We interpreted the combination results of Qp, Qs and Qp/Qs ratio structures with previous seismic velocities (Vp, Vs and Vp/Vs ratio). We can see that the high attenuation value (low Q value) and low velocity anomaly structures may be corresponded to fluid-filled rock and also fault segment. |