Seasonal and daily variation of radon at 10 m depth in borehole, Garhwal Lesser Himalaya, India

V M Choubey; B R Arora; S M Barbosa; Naresh Kumar; Leena Kamra

doi:10.1016/j.apradiso.2011.03.027

Seasonal and daily variation of radon at 10 m depth in borehole, Garhwal Lesser Himalaya, India

Appl Radiat Isot. 2011 Jul;69(7):1070-8. doi: 10.1016/j.apradiso.2011.03.027. Epub 2011 Apr 8.

Authors

V M Choubey¹, B R Arora, S M Barbosa, Naresh Kumar, Leena Kamra

Affiliation

¹ Wadia Institute of Himalayan Geology, 33 General Mahadeo Singh Road, Dehradun, India.

PMID: 21482123
DOI: 10.1016/j.apradiso.2011.03.027

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.