Earthquake-precursory characteristics of variation in total content of dissolved CO_2 (TCD-CO_2 parameter) in geothermal fluid

摘要

In the neotecotnically active regions, the distribution of a lot of CO_2 discharges is restricted in the seismically active belts. It indicates that some CO_2 discharges could be related to seismic activity. The evidence of stable carbon isotopes suggests that CO_2 is mostly derived from the deep crust. Because the solubility of CO_2 increases with the rising fluid pressure, the deep-seated CO_2 always migrates and releases together with the geothermal water. The observational method of the TCD-CO_2parameter has been reported.