汶川<i>M</i><sub>S</sub>8.0地震前成都台NE测线 地电阻率异常的进一步研究

钱家栋; 马钦忠; 李劭秾

doi:10.3969/j.issn.0253-3782.2013.01.002

汶川M_S8.0地震前成都台NE测线地电阻率异常的进一步研究

doi: 10.3969/j.issn.0253-3782.2013.01.002

1.
中国北京 100036 中国地震局地震预测研究所
2.
中国上海 201203 上海市地震局
3.
中国郑州 450000 郑州大学信息工程学院

基金项目: 中国老科协地震分会2011年度基金项目资助.

详细信息

通讯作者:
钱家栋, e-mail: jdqian@seis.ac.cn

中图分类号: P319
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出版历程
- 收稿日期: 2012-12-03
- 修回日期: 2013-01-10
- 刊出日期: 2013-01-01

Further study on the anomalies in apparent resistivity in the NE configuration at Chengdu station associated with Wenchuan M_S8.0 earthquake

1.
Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China
2.
Earthquake Administration of Shanghai Municipality, Shanghai 201203, China
3.
School of Information Engineering, Zhengzhou University, Zhengzhou 450000, China

摘要

摘要: 汶川M_S8.0地震前，位于震源区内的成都台NE测线地电阻率显示了数年大幅度趋势下降异常，其年变化甚至严重畸变到消失的程度，它和多年来我国7级以上大地震记录到的异常形态有极大的相似性，被认为是最清晰的异常之一. 然而，长期的观测表明，成都台NE测线地电阻率与测区潜水水位年变化呈正相关. 因此，关注异常发展过程中测区水位变化，成为汶川M_S8.0地震震例地电阻率异常科学总结的重要课题之一. 本文通过对成都台建台以来NE测线地电阻率的全程分析，确认与汶川M_S8.0地震有关的地电阻率异常变化属于全程变化的第三阶段(1999—2008年). 分析了第三阶段同步观测的地下水位数据，并进行了地电阻率和地下水位趋势变化的综合分析. 最终确认与汶川M_S8.0地震有关的地电阻率异常经历了前、后两个时段：前期2004年2月—2006年2月，小幅趋势上升，幅度约为1.9％；后期2006年2月—2008年2月，趋势下降，幅度达-6.8％，如此大幅度快速下降现象，是成都台建台30多年来从未见到的. 基于前人开展的试验工作的启示，推测与此下降相应的测区底层(h＞96.6 m)介质电阻率减小量可达22.3％左右. 其量级之大，须用承载标本试验中岩石破裂前微裂隙广泛发育和排列趋同化导致的地电阻率变化来解释，由于成都台位于汶川地震震源区内的特殊位置，可以作为汶川地震孕震物理过程研究中的重要约束条件之一.
- 地电阻率 /
- 地下水位 /
- 年变化 /
- 汶川M_S8.0地震 /
- 趋势异常
Abstract: Chengdu geoelectric station is located merely 35 km from the epicenter of the 12 May 2008 Wenchuan M_S8.0 earthquake. This paper deals with the remarkable descending tendency of apparent resistivity with strong distortion of seasonal variations at the station associated with the Wenchuan earthquake on a new point of view. Firstly， the long-term observation data since 1978 were applied to the investigation in order to determine the stage features in the whole course of the apparent resistivity observation; secondly， more attention was paid to the close relationship between apparent resistivity and water-table changes to recognize the possible influence of the water-table variations on the determination of tendency anomalies in apparent resistivity at Chengdu station; and thirdly， the previous results of in-situ experiments at the station were utilized to give a nearly quantitative analysis of the tendency anomaly in the third stage of the whole courses of observation. The analysis has identified two segments of anomalous behaviors in apparent resistivity which could be associated with the Wenchuan M_S8.0 earthquake after checking the influence of water-table variations. The first segment showed a slight ascending of 1.9% from Feb. 2004 to Feb. 2006; the second one had a very huge descending of -6.8% from Feb. 2006 to Feb. 2008. The deduced variations of -22.3% in true resistivity in the deep media， which had never been seen in the previous time of the whole course of observation at the station， could be taken as one of the constraints for researches on the preparation processes of the earthquake. The results have shown important complements to the case studies of apparent resistivity anomalies in China， especially to those with strong distortion of seasonal variations in the anomaly development without synchronous observation of water-table variations.
- apparent resistivity /
- water table /
- seasonal variation /
- Wenchuan M_S8.0 earthquake /
- tendency anomaly

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图 1 成都(郫县)台测区测深曲线(a)和(含多极距)观测装置布设示意图(b)

Figure 1. Sounding curves (a) and layout of the (multi-separation) configurations of apparent resistivity observation system (b) at Chengdu station

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图 2 成都台地电阻率1979—2008年全程观测结果

(a) NE和NW测线年均值； (b) 两测线年变化距平分析比较

Figure 2. Results of the whole course of apparent resistivity observation at Chengdu station during 1979—2008

(a) Annual mean values in the configurations of NE and NW directions; (b) Comparison between seasonal variations in the configurations of the two directions from statistical analysis

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图 3 成都台自建台以来NE测线地电阻率观测全程月均值曲线

Figure 3. Monthly average of apparent resistivity in the configuration of NE direction at Chengdu station since it was set up

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图 4 甘肃嘉峪关台(a)和四川成都台(b)地电阻率与地下水位年变化的对比

Figure 4. Contrast of annual variations in apparent resistivity and water table at Jiayuguan station， Gansu Province (a) and Chengdu station， Sichuan Province (b)

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图 5 成都台多极距观测试验与地电阻率反演结果

(a) 成都台上部三层真电阻率变化与其地下水位变化的对比； (b) 底层真电阻率时间变化与小金地震

Figure 5. Inversion results with apparent resistivity data observed in the multi-separation experiments at Chengdu station

(a) Temporal changes of true resistivity at the top 3 layers versus variations of water table at Chengdu station; (b) Temporal changes of true resistivity at the deepest layer before the Xiaojin M6.6 earthquake in 1989

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图 6 成都台1985—1990年间地电阻率和测区地下水位年变化距平分析

Figure 6. Statistical analysis of annual variation of apparent resistivity and water table during 1985—1990 at Chengdu station

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图 7 成都台2003年1月—2008年7月NE测线地电阻率与地下水位变化(a)及 2004—2008年修正前后地电阻率曲线对比(b)

Figure 7. Variations of apparent resistivity and water table from Jan. 2003 to July, 2008 at Chengdu station (a) and contrast between original and revised apparent resistivities from 2004 to 2008 (b)

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表 1 成都台第三阶段地电阻率与地下水位变化参数对比

Table 1. Parameters of variations of apparent resistivity and water table in the third stage of the whole course of observation at Chengdu station

参考文献(25)

杜学彬. 2010. 在地震预报中的两类视电阻率变化[J]. 中国科学: 地球科学, 40(10): 1321-1330.

关华平, 张学民, 李美. 2008. 汶川地震前的地电阻率异常分析[J]. 国际地震动态, (11): 144.

金安忠. 1981. 地电阻率正常变化的初步研究[J]. 地球物理学报, 24(1): 92-106.

陆阳泉, 赵家骝, 钱家栋, 王玉祥, 刘建毅. 1998. 利用大样本岩石破裂实验模拟扩容-扩散孕震模式的某些结果(Ⅰ) [J]. 地震学报, 20(2): 194-200.

钱家栋, 陈有发, 金安忠. 1985. 地电阻率法在地震预报中的应用[M]. 北京: 地震出版社: 103-107.

钱家栋, 赵和云. 1988. 地电阻率的数值模拟和多极距观测系统[J]. 地震学报, 10(1): 77-88.

钱家栋, 赵玉林, 桂燮泰, 陈有发, 赵和云.1991. 国内外地电预报地震研究动态与展望[M]//中国地震预报方法研究. 北京: 地震出版社: 266-276.

钱家栋. 1993. 与大震孕育过程有关的地电阻率变化研究[J]. 中国地震, 9(4): 341-350.

钱家栋, 曹爱民. 1998. 1976年唐山7.8级地震地电阻率和地下水前兆综合物理机制研究[J]. 地震, 18(增刊): 1-9.

钱家栋. 2002. 中国地电学研究[M]//陈运泰(主编). 20世纪中国学术大典: 固体地球物理学. 福州: 福建教育出版社: 17-24.

薛顺章, 温新民, 董永德, 梁子彬, 张庆渊, 赵和云. 1994. 地电阻率预报地震新方法的研究[J]. 地震学报, 16(2): 227-234.

赵和云, 钱家栋. 1987. 郫县台多极距观测资料的反演和分析[J]. 中国地震, 2(增刊):74-78.

中国地震局监测预报司. 2010. 地震电磁学理论基础与观测技术. 北京: 地震出版社: 73-77.

Archie G E. 1942. The electrical resistivity log as an aid in determining some reservoir characteristics[J]. Trans AIME, 146(1): 54-62.

Brace W F, Orange A S. 1968a. Electrical resistivity changes in saturated rocks during fracture and frictional sliding[J]. J Geophys Res, 73(4): 1433-1445.

Brace W F, Orange A S. 1968b. Further studies of the effect of pressure on electrical resistivity of rocks[J]. J Geophys Res, 73(16): 5407-5420.

Brace W F. 1975. Dilatancy-related electrical resistivity changes in rocks[J]. Pure Appl Geophys, 113(1): 207-217.

Lu J, Xue S Z, Qian F Y, Zhao Y L, Guan H P, Mao X J, Ruan A G, Yu S R, Xiao W J. 2004. Unexpected changes in resistivity monitoring for earthquakes of the Longmen Shan in Sichuan, China, with a fixed Schlumberger sounding array[J]. Phys Earth Planet Inter, 145(1-4): 87-97.

Ma Q Z. 2002. The boundary element method for 3-D dc resistivity modeling in layered earth[J]. Geophysics, 67(2), 610-617.

Qian J D, Gui X T, Ma H Z, Ma X K, Guan H P, Zhao Q M. 1984. Observations of apparent resistivity in the shallow crust before and after several great shallow earthquakes[C]//Proceedings of the International Symposium on Earthquake Prediction, UNESCO, Paris. Tokyo: Terrapub: 145-156.

Qian J. 1985. Regional study of the anomalous changes in apparent resistivity before the Tangshan earthquake (M=7.8, 1976) in China[J]. Pure Appl Geophys, 122(1984/85): 901-920.

Qian J D, Gui X T, Lu Y Q, Guan H P. 1996. Review on the observation and experiment in the earthquake prediction by using geoelectrical method[M]//The Selected Papers of Earthquake Prediction in China. Beijing: Seismological Press: 170-185.

Zhao J L, Wang L W, Qian J D. 2011. Research on geo-electrical resistivity observation system specially used for earthquake monitoring in China[J]. Earthq Sci, 24(6): 497-511.

Барсуков О М. 1979. Возможная причина электрических предвестников землетрясений. Физика Земли, (8): 85-89.

Параснис Д С.1965. Принципы Прикладной Геофизики. Мир. 81-135.

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