ABSTRACT

In this paper, we present the results of the first experience for spring water ²²²Rn concentration continuous monitoring in Jowshan hot spring, SE Iran, from December 2007 to July 2008. This hot spring is located on the active Gowk Fault. In addition to physic-chemical parameters of water and water chemistry, dissolved radon, and air and water temperatures, were measured at 10-minute time intervals. Measurements and analyses correlated with seismological data within a radius 250 km from the spring. Relatively good relationships between radon level variations and earthquake frequency, especially for events which monitoring site lie within the stress-strain field of earthquake, were observed. Results show that radon precursor time negatively correlate with the distance between the epicenters and monitoring station, but positively correlate with the magnitude of the earthquake events. Nevertheless, continuous monitoring to attain local pattern is necessary. Temperature, electrical conductivity and pH measurements do not show any correlation with seismic activity and radon variations in this time-window of monitoring. Monthly spring water samples analyzing for major components demonstrate no mixing ground-water has been taken place during the period of monitoring. While deep temperature estimation based on the [Na–K–Ca] geothermometery shown coinciding of temperature increasing with radon anomaly in one case. More data and shorter sampling time interval for spring water is required before we can conclude that the variation of estimated deep temperature is feasible to be as an earthquake precursor.