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Abstract The West China Borehole Strainmeter Networks are established in the late eighties of the twentieth century. RZB-1 borehole strainmeter with strain sensitivity of 10－10 and strain drift less than 10－7/year were adopted to detect the crustal strain energy built-up from active tectonic processes in order to study earthquake precursors. Strainmeters were installed in 9 observatories in three provinces of west China，Xinjiang，Gansu and Sichuan，and are kept on operating up to the present. This paper summarizes the observation data of strainmeters and their application to monitoring and predicting strong earthquakes occurring round the station. Four kinds of abnormal strain changes before big earthquakes are evident，that is，(1) distortion of strain tides and annual variation form，(2) strain building up of amplitude as much as 10－6 with compressive and tensive jumps，(3) duration of abnormal strain accumulation lasting few months，and (4) axis of the major principal stress turning and pointing to epicentre before the coming shock. At last，three suggestions are brought forward to help developing borehole observation and retative research in China.
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Received: 01 April 2004
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MEI Xiancheng1, 2, CUI Zhen1, 2*, SHENG Qian1, 2, CHEN Jian1, 2, FEI Yang1, 2, TANG Langzhou1, 2, ZHAO Xu3, LI Ruohan4, HUANG Jingqi5. Physical modeling on the coupling effect of strong shaking-fault movement to a fault-crossing tunnel (I): Experimental system and method[J]. , 2026, 45(5): 1304-1320. |
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