Soil Gas Method to Identify the Surface Distribution of Shan-Chiao Fault, Taipei Region
Date Issued
2005
Date
2005
Author(s)
Su, Chun-Hsu
DOI
zh-TW
Abstract
Anomalous soil gas compositions are generally revealed on surface of fractures and fault zones. Therefore, the distribution and variation of soil-gas components are often used to trace the locations of faults and even as to be precursors of earthquakes. Due to low concentrations in air, He, Rn, CO2 and CH4 are sensitive to reflect soil-gas anomalies. Helium, an inert gas with high mobility and low solubility, has higher concentration in the crust due to radioactive decay. Therefore, helium can easily migrate through fractures or faults without fractionation.
We attempted to trace the surface distribution of the Shan-Chiao fault by utilizing soil-gas survey. Soil gas was systematically collected at depth around 0.7-1.0 meter with metallic probes. Several sampling profiles across possible location of the Shan-Chiao fault were proceeded in Er-Chong Flood-diversion Canal (Wu-Gu area), Tai-Shan area and Xin-Zhuang area of the Taipei Basin.
In Er-Chong Flood-diversion Canal, anomalously high soil He, CO2 and CH4 was distributed over the possible location of the Shan-Chiao fault. In other areas, the soil-gas anomalies (mainly He) are listed bellow: (1) Wen-Zi Canal to Lu-Zhou Riverbank (Wu-Gu area),spreading about 700 meters wide; (2) area between Zhong-Gang Escape Canal and Ming-Zhi Road (Tai-Shan area), spreading about 120-170 meters wide the. Shan-Chiao fault may pass through Yi-Xue Junior High School, the front part of Ming-Zhi Elementary School, and extend southward to Zhong-Shan Road; (3) from Zhong-Zheng Road to Ta-Liao-Keng Stream (Xin-Zhuang area),spreading about 100-450 meters wide. The Shan-Chiao fault may pass through Shuang-Feng Park in Long-An Road and extend southward to the play ground of Dan-Feng Junior High School. Further investigations are required to check if the fault stretches to identify whether the Shu-Lin area.
The preliminary results show that the distribution of soil-gas anomalies, especially He abundance, correlates well with the possible surface distribution of the Shan-Chiao fault. The results also show that soil gas survey is effective to identify the locations of faults. By combining this technique with isotopic analysis, we can have more detail and precise information of the Shan-Chiao fault.
Subjects
氦氣
土壤氣體
山腳斷層
He
Soil gas
Shan-Chiao fault
Type
thesis
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