title: Seasonal and daily variation of radon at 10 m depth in borehole, Garhwal Lesser Himalaya, India.
abstract: Mostly accepted and widely reported radon (Rn(222)) measurements, a tool for earthquake precursor research, is a part of multi-parametric geophysical observation in the Garhwal Lesser Himalaya for earthquake related studies. Radon is being recorded continuously at an interval of 15 min at 10 m depth in a 68 m deep borehole. Three years high resolution 15 min data at 10 m depth shows a complex trend and has a strong seasonal effect along with some diurnal, semi-diurnal and multi-day recurring trends. A well-defined seasonal pattern is prominent with a high emanation in summer and low values in winter accounting for about a 30% decrease in count values in winter when the atmospheric temperature is very low at this station located 1.90 km above mean sea level. Diurnal, semi-diurnal and multi-day trends in this time-series are mainly observed during April-May and October-November. This is the period of spring and autumn when there is a high contrast in day-night atmospheric temperature. Hence the high fluctuation in Rn concentration is mainly caused by the temperature contrast between the air-column inside the borehole and the atmosphere above the earth's surface.
authors.affiliation: Wadia Institute of Himalayan Geology, 33 General Mahadeo Singh Road, Dehradun, India.
authors.forename: V M
authors.initials: VM
authors.lastname: Choubey
authors.forename: B R
authors.initials: BR
authors.lastname: Arora
authors.forename: S M
authors.initials: SM
authors.lastname: Barbosa
authors.forename: Naresh
authors.initials: N
authors.lastname: Kumar
authors.forename: Leena
authors.initials: L
authors.lastname: Kamra