Pronounced soil-radon anomaly—Precursor of recent earthquakes in India

The real time radon monitoring is an extensively studied area in order to give premonitory signs prior to an earthquake. The strain changes that occurred within the earth surface during earthquake is expected to enhance the radon concentration in soil gas. In order to support this theoretical view, we have performed an experiment on measuring radon concentration in soil gas with the use of CR-39—solid state nuclear track detector (SSNTD). The study has been performed at Jadavpur University, Kolkata, India. This paper reports essentially the observation of radon anomaly for the earthquakes that occurred during the period of November 2005–October 2006 within the range of 1000 km from the measuring site and of M⩾4M⩾4. The study is important as no such work has been done at Kolkata, India, which is a relatively geologically stable area.