Long-term In Situ Permeability Variations of an Active Fault Zone in the Interseismic Period
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Hydraulic properties were estimated by analyzing the continuous water level response to Earth tides in a well intersecting the Qujiang active fault (in Yunnan, China) which had ruptured during the 1970 Tonghai Ms 7.8 earthquake. The in situ permeability from 2001 to 2018 fluctuates around 4 × 10−14 m2, with a variation of about 25%, and the hydraulic diffusivity varies from 0.29 to 0.55 m2/s. The permeability is comparable to the permeability estimated from the slug tests. According to the results, we suggest that the permeability in the damage zone of the Qujiang fault is dynamic, and the fault zone provides a localized horizontal conduit for the along-fault fluid flow. Furthermore, the shallow part of the Qujiang fault may heal incompletely or not heal after the Tonghai earthquake, and the fault may be stable between 2001 and 2018.
KeywordsPermeability fault zone well water level tidal analysis Tonghai earthquake
The water level data, earthquake catalog, and meteorological data were obtained from the China Earthquake Networks Center. This research work was supported by the National Natural Science Foundation of China (U1602233), the National Key R&D Program of China (2018YFC1503305), and the Spark Program of Earthquake Science of China (XH19055). We are grateful to Dr. Giuliana Rossi and an anonymous reviewer for their helpful comments and suggestions.
- China Earthquake Administration. (2008). The Chinese seismic intensity scale (GB/T 17742–2008). Beijing: Standards Press of China (in Chinese).Google Scholar
- Hu, X. J., Fu, H., & Li, Q. (2018). Preliminary study on abnormal mechanism of groundwater level rising in southern Yunnan. Acta Seismologica Sinica,40(5), 620–631. (In Chinese with English abstract).Google Scholar
- Ingebritsen, S. E., & Manning, C. E. (2010). Permeability of the continental crust: Dynamic variations inferred from seismicity and metamorphism. Geofluids,10(1–2), 193–205.Google Scholar
- Liu, Z. Y., Huang, F. G., & Jin, Z. L. (1999). The 1970 Tonghai earthquake (pp. 31–64). Beijing: Seismological Press. (In Chinese with English abstract).Google Scholar
- Shimamoto, H. N., Tanikawa, W., Wibberley, C. A. J., & Uehara, S. (2004). Fault-zone permeability structures and their implications for earthquake mechanisms and geo-engineering problems. In: Proceedings of ISRM International Symposium 3rd ARMS, Millpress, Rotterdam 1025.Google Scholar
- Yunnan Earthquake Administration. (2005). Seismic monitoring record of Yunnan Province. Beijing (in Chinese): Seismological Press.Google Scholar
- Zhang, Z. C. (1988). Earthquake cases in China (1966-1975). Beijing: Seismological Press. (In Chinese).Google Scholar
- Zhang, S. C., & Liu, B. C. (1978). Seismic geological characteristics of Tonghai earthquake in 1970. Scientia Geologica Sinica,4, 323–325. (In Chinese with English abstract).Google Scholar