英文摘要 |
The present study is proposed to investigate geochemical variations of soil-gas composition in the vicinity of geologic fault zones of Hsincheng fault and the Hsinhua fault within the Hsinchu and Tainan areas, respectively, and to determine the influence of such formations on enhanced concentrations of different gases in soil. Active faults favour gas leaks because they increase permeability of soil which help the gas to migrate easily. Spatial variability of gases like radon, helium, carbon-di-oxide, methane etc. in soil-gas can be used for finding fault system. Soil-gas surveys have been conducted across the Hsincheng fault and Hsinhua fault, to find out the regional activity of these fault systems. During the surveys soil-gas samples were collected along the traverses crossing the observed structures. The collected soil-gas sample bags are analyzed for He, Rn, CO2, CH4, Ar, O2 and N2. The data analysis clearly reveals anomalous values along the fault. To find the fault system, where the migration of gases is governed by advection, it is essential to identify the anomalies in radon, helium and carrier gases like CO2, CH4, and N2 together. The consistency of this pattern confirms that soil-gas can act as a powerful tool for the detection and mapping of active fault zones. A continues monitoring station has been established inside the Hsinchu National Science Industrial Park(HNISP) at the end of September, 2005. Preliminary results of the monitoring station shows that the site is good the earthquake monitoring and soil-gas variations have shown good correlation with impending earthquakes. |