Radon anomaly in a thermal spring in Xiamen, China, related to the 1999 Chi-Chi earthquake (Ms = 7.6)

摘要

Monitoring data of radon and chemical parameters in water from a thermal spring in Xiamen,China, are investigated for possible correlations with the seismic activity of the September 21, 1999 Chi-Chi earthquake (Ms = 7.6). In the mainland, this thermal well is the nearest monitoring station to Taiwan. Precursory fluctuations in radon and chloride concentrations were observed before the earthquake with those in the period between April and September, 1999, possibly being the mid-term precursory anomaly of the Chi-Chi earthquake.The short-term radon anomaly that correlates with the main seismic event was well observed in the monitoring well. We suggest that radon anomalies in groundwater complemented with other hydrochemical parameters could be used more accurately as a preceding indication or even as a prediction of seismic events, if observed under suitable geological conditions.