Simultaneous declines in radon and methane precursory to 2008 M <Subscript>W</Subscript> 5.0 Antung earthquake: corroboration of in-situ volatilization

Radon volatilization mechanism into the gas phase was hypothesized to explain the anomalous decline in groundwater radon precursory to the 2003 M <Subscript>W</Subscript> = 6.8 Chengkung earthquake in Taiwan. We initiated the monitoring of both radon and methane in the groundwater since November 2007 at well D1 in the Antung hot spring. The mechanism of in-situ radon volatilization has been corroborated by the simultaneous anomalous declines in groundwater-dissolved radon and methane precursory to the 2008 M <Subscript>W</Subscript> 5.0 Antung earthquake. Copyright Springer Science+Business Media B.V. 2010