Tripob Bhongsuwan, Pattama Pisapak, and Helmut Dürrast

pp. 609 - 616

Abstract

Measurements of radon concentration in soil gas were conducted at ten stations (ST1-ST10), located mainly in the
Khlong Marui Fault Zone, Thap Put District, Phang Nga Province over a period from 28 January to 25 April, 2007. The results
of the radon concentration were presented as the variation of cumulative alpha track over a week period. At Station ST10 the
radon concentrations are in general higher than those at other stations for every week. Two significant radon anomalies were
found to have the concentration above the mean value plus one standard deviation. During the period of monitoring the
local and regional earthquake activities were observed showing patterns consistent with the occurrence of the radon anomalies. The maximum radon concentration is interpreted to be related to a possible influence of the pressure and stress increased
in the subsurface. An increase in the number of earthquakes is observed correlating to a lower radon concentration when the
subsurface pressure dropped due to tectonic stress release by seismic activities. Therefore, it would be possible to use the
variation of soil gas radon concentration as an earthquake precursor in the Khlong Marui Fault Zone.