地震研究

利用结合波形互相关技术的双差定位法对龙滩库区2006年9月30日至2013年5月26日发生的3 682次地震进行精定位,获得了精度更高的定位结果,平均理论误差小于10 m。精定位结果显示:蓄水后龙滩库区中小地震活动呈现明显的丛集性,主要集中在罗妥、八茂、拉浪、坝首、布柳河以及库区下游的天峨县城6个区域,每个地震丛的分布范围在10 km内,优势深度为4～9 km,优势展布方向与穿过该地震丛的主要断裂带的走向或倾向一致,表明库区地震活动基本分布在河流及断层附近10 km范围内,表现出水库诱发地震活动典型的“双十”特征。研究成果可为龙滩水库续建工程诱发地震的预测与地震安全性评价提供依据。

Using the double-difference location algorithm combined with waveform cross-correlation technique, we relocated 3 682 earthquakes occurred around Longtan Reservoir from Sep.30, 2006 to May.26, 2013. The relocating results are more precise than that of network catalogue, and its logically mean error is less than 10 m. The precise location results show that, the distribution of mid-small earthquakes shows obvious cluster in the 6 regions of Luotuo, Bamao, Lalang, Bashou, Buliuhe and Tian'e County after impounding. The distribution range of each earthquakes cluster is no more than 10 km and the focal depths dominantly distributed in 4～9 km, and its advantageous spread direction is consistent to the strike or trend of main faults which pass through the earthquakes cluster. These results indicate that the earthquakes in the reservoir basically distribute in the range of less than 10 km around the rivers and faults, which shows the typical “double ten” characteristics of reservoir-induced seismic activity. The obtained research results are useful to predict earthquake induced by Longtan Reservoir reconstruction project and could provide the basis for seismic safety assessment.

引言
1 研究区概况
2 研究方法与资料处理
3 结果分析
4 讨论与结论

图1 龙滩水库断裂、河流、台站及蓄水后地震分布图(地震为广西地震台网中心定位结果)<br/>Fig.1 Distribution map of fault, river, station and earthquakes after reservoir impoundment in the Longtan Reservior and its adjacent region(the earthquakes are located by Guangxi Seismic Network)

图1 龙滩水库断裂、河流、台站及蓄水后地震分布图(地震为广西地震台网中心定位结果)
Fig.1 Distribution map of fault, river, station and earthquakes after reservoir impoundment in the Longtan Reservior and its adjacent region(the earthquakes are located by Guangxi Seismic Network)

图2 Pg波互相关的部分图形<br/>(a)XMP;(b)RD;(c)PHD;(d)JL<br/>Fig.2 Examples of waveform of cross-correlation about Pg wave

图2 Pg波互相关的部分图形
(a)XMP;(b)RD;(c)PHD;(d)JL
Fig.2 Examples of waveform of cross-correlation about Pg wave

表1 图2中地震对的详细信息<br/>Tab.1 Detailed information of seismic doublet showing in Fig.2

表1 图2中地震对的详细信息
Tab.1 Detailed information of seismic doublet showing in Fig.2

图3 波形互相关的时间补偿统计<br/>Fig.3 Statistics of time compensation of waveform cross-correlation

图3 波形互相关的时间补偿统计
Fig.3 Statistics of time compensation of waveform cross-correlation

图4 结合波形互相关技术的双差定位法定位结果<br/>Fig.4 Relocation result by using double-difference location algorithm combined with waveform cross-correlation technique

图4 结合波形互相关技术的双差定位法定位结果
Fig.4 Relocation result by using double-difference location algorithm combined with waveform cross-correlation technique

图5 台网定位和双差定位结果的震源深度对比及精定位结果误差统计<br/>(a)台网定位和双差定位结果的震源深度分布随时间变化图;(b)采用地震目录和波形互相关资料联合定位结果的残<br/>差均方根;(c)只采用地震目录资料定位结果的残差均方根; 东西向(d)、<br/>南北向(e)和垂直向(f)的定位误差<br/>Fig.5 Comparison of focal depth located by network catalogue and double-difference location and statistics of precise relocation result error (a)focal depth located by network catalogue and double-difference location vary with time;(b)residual RMS of joint relocation by catalogue and waveform cross-correlation technique;(c)residual RMS of relocation by double-difference algorithm with catalogue merely; the location error in east-west(d), north-south(e)and vertical(f)respectively

图5 台网定位和双差定位结果的震源深度对比及精定位结果误差统计
(a)台网定位和双差定位结果的震源深度分布随时间变化图;(b)采用地震目录和波形互相关资料联合定位结果的残
差均方根;(c)只采用地震目录资料定位结果的残差均方根; 东西向(d)、
南北向(e)和垂直向(f)的定位误差
Fig.5 Comparison of focal depth located by network catalogue and double-difference location and statistics of precise relocation result error (a)focal depth located by network catalogue and double-difference location vary with time;(b)residual RMS of joint relocation by catalogue and waveform cross-correlation technique;(c)residual RMS of relocation by double-difference algorithm with catalogue merely; the location error in east-west(d), north-south(e)and vertical(f)respectively

图6 龙滩水库蓄水后库区地震震源深度统计结果<br/>(a)地震丛Ⅰ;(b)地震丛Ⅱ;(c)地震丛Ⅲ;(d)地震丛Ⅳ;(e)地震丛Ⅴ;(f)地震丛Ⅵ;(g)所有地震<br/>Fig.6 Statistical result of focal depth of earthquakes occurred after reservoir impoundment in the Longtan Reservoir region (a)earthquake clusters Ⅰ;(b)earthquake clusters Ⅱ;(c)earthquake clusters Ⅲ;(d)earthquake clusters Ⅳ; (e)earthquake clusters Ⅴ;(f)earthquake clusters Ⅵ;(g)all earthquakes

图6 龙滩水库蓄水后库区地震震源深度统计结果
(a)地震丛Ⅰ;(b)地震丛Ⅱ;(c)地震丛Ⅲ;(d)地震丛Ⅳ;(e)地震丛Ⅴ;(f)地震丛Ⅵ;(g)所有地震
Fig.6 Statistical result of focal depth of earthquakes occurred after reservoir impoundment in the Longtan Reservoir region (a)earthquake clusters Ⅰ;(b)earthquake clusters Ⅱ;(c)earthquake clusters Ⅲ;(d)earthquake clusters Ⅳ; (e)earthquake clusters Ⅴ;(f)earthquake clusters Ⅵ;(g)all earthquakes

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备注

引言

1 研究区概况

2 研究方法与资料处理

3 结果分析

4 讨论与结论

期刊信息