SUMMARY

Comparative measurement of soil gas radon using solid state nuclear track detectors

(SSNTD'S) and RAD7 in studying active tectonic faults in Chí Linh area (Hải Dương)

Phạm Tích Xuân, Phạm Thanh Đăng, Nguyễn Xuân Quả,

Vũ Văn Chinh, Nguyễn Văn Phổ, Đoàn Thu Trà, Nguyễn Thị Liên

The radon (Rn) content of soil gas was measured in parallel by two methods: the solid-state nuclear track detectors (SSNTD's) and RAD7 in the area of Hoàng Tân commune (Chí Linh, Hải Dương) to determine the activities of the Trung Luong fault and its sub-faults in this area, and at the same time assessed the possibility of using the RAD7 to measure the soil gas radon in studying the active faults. According to the solid-state nuclear track detectors, Rn content fluctuates in the range of 90 Bq.m-3 to 53,940 Bq.m-3, according to the RAD7 they fluctuate in the range 110 Bq.m-3 to 103,000 Bq.m-3. Thirteen anomalies of Rn were determined with the radon activity indice (KRn) from 3.4 to 13.6, ie from low to high levels. These anomalies are located on or adjacent to the Trung Luong main fault and its sub - faults that confirmed the existence of these faults. Moreover, the KRn index shows that these faults are active in present-time. The Rn content measured by the RAD7 method is usually higher than that by the solid-state nuclear track detectors. Although there are differences in absolute values, but the characteristics of the concentration distribution of Rn on the measuring profiles, especially anomalies are quite similar for both methods, consequently the RAD7 can be used to measure soil gas radon in studying the active faults.

Keywords: Radon, RAD7, Solid-State Nuclear Track Detector, positive radon index, active fault