Radon as an earthquake precursor in and around northern Pakistan: A case study

Abstract

Abnormal increase in radon (²²²Rn, half-life = 3.82 days) concentration has frequently been observed in soil gas environments before major earthquakes. This observation suggests that radon emission may be suitable for use as an earthquake precursor. The objective of this study is to evaluate the use of radon emission as an earthquake precursor in and around northern Pakistan. For this purpose, radon was monitored in soil gas at the foothills of Maragalla, Islamabad. The data presented in this work was obtained using a radon monitor (RTM2200) ion-implanted silicon detector and covers a period from autumn 2014 to spring 2015. Our results suggest that anomalous radon concentrations were observed before five earthquake events, which had magnitudes (m_b) of 4.2, 4.2, 4.7, 4.8 and 5.4. The values of earthquake preparation zone (R_E/R_D) for these events were found to be 1.5, 1.5, 0.49, 0.89 and 1.26, respectively. Furthermore, temporal investigation of radon concentration with respect to temperature, pressure and relative humidity suggests no significant correlation, which indicates that abnormal increase was not associated with the meteorological parameters but with precursory signals before earthquake events.