Application of recurrent radon precursors for forecasting large earthquakes (Mw > 6.0) near Antung, Taiwan

Radon anomalies in groundwater were recorded prior to three major earthquakes – (1) 2003 Mw = 6.8 Chengkung, (2) 2006 Mw = 6.1 Taitung, and (3) 2008 Mw = 5.4 Antung. The epicenters were located 24 km, 52 km, and 13 km, respectively, from the Antung radon-monitoring station. Prior to the three major earthquakes, radon decreased from background levels of 29.3 ± 1.7, 28.2 ± 2.1, and 27.2 ± 1.8 Bq dm−3 to minima of 12.1 ± 0.3, 13.7 ± 0.3, and 17.8 ± 1.6 Bq dm−3, respectively. Based on the radon precursory data, this paper correlates the observed radon minima with earthquake magnitude and precursory time. The correlations provide a possible means for forecasting local disastrous earthquakes in the southern segment of coastal range and longitudinal valley of eastern Taiwan.