地震研究

运用反投影远震P波记录法研究实皆断裂上中强地震震源破裂过程^*

李丹宁¹,马志斌²,徐彦³

(1.云南省地震局, 云南昆明 650224; 2.云南省有色地质局,云南昆明 650051; 3.云南大学资环学院地球物理系,云南昆明 650091)

Research on the Source Ruptures of Mid-strong Earthquakes in Sagaing Fault by Back-projection of Teleseismic P-waves

LI Danning¹, MA Zhibin², XU Yan³

(1.Earthquake Administration of Yunnan Province, Kunming 650224, Yunnan, China)(2.Nonferrous Geological Bureau of Yunnan Province, Kunming 650051, Yunnan, China)(3.School of Resource Environment and Earth Sciences, Yunnan University, Kunming 650091, Yunnan, China)

Keywords：Sagaing Fault; back projection of teleseismic P waves; source rupture process

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参考文献

运用反投影远震P波记录法对发生于实皆断裂上的3个M≥6地震的震源破裂过程进行了研究。运用4阶方根叠加法及滑动时间窗对总长100 s(发震前20 s到震后80 s的时间段)的波形进行反投影,结果显示:3个地震的震源破裂时间总长在15～22 s之间,破裂尺度在25～50 km之间。对于不同频率范围采用不同时间窗长进行分析,发现其所显示的破裂细节有所区别,体现了实皆断裂不同段上强震破裂的复杂性,表明了反投影远震P波记录法在反演震源破裂过程时的灵活性和实用性,有助于对中强地震震源破裂过程的研究。

We studied the source rupture processes of three M≥6 earthquakes(1992-06-15, M_W6.3; 2000-06-07, M_W6.4; 2003-09-21,M_W6.7)on the sagaing fault by back projection of teleseismic P waves, and applied the 4^th root stack method and moving window to do the back-projection on the 100 s waveform which started 20 s before the earthquake and ended 80 s after the earthquake. The back-projection result shows that the total source rupture time of the three earthquakes are 15～22 s and the rupture length is about 25～50 km. For analyzing the different frequency range by using different time window, we found that the rupture details shows different, which reflected that the complexity of source rupture of strong earthquake in different segment of Sagaing Fault. It also represented the flexibility and practicality of back-projection of teleseismic P-waves in the inversion of seismic source rupture process, and this method is helpful for studing the source rupture process of mid-strong earthquakes.

引言
1 研究区域概况
2 数据选取与计算方法
3 讨论
4 结论

图1 研究区域及3次M≥6.0地震震源机制解<br/>Fig.1 Map of focal mechanisms of three M≥6.0 earthquakes and the studied area

图1 研究区域及3次M≥6.0地震震源机制解
Fig.1 Map of focal mechanisms of three M≥6.0 earthquakes and the studied area

图2 1992年6月15日MW6.3地震全球子台网所选台站分布及ARF<br/>(a-1)震中以东9个台站的分布;(a-2)震中以东9个台站记录所得的ARF; <br/>(b-1)震中以西9个台站的分布;(b-2)震中以西9个台站记录所得的ARF; <br/>(c-1)所选台站在全球的分布;(c-2)18个台站同时组网所得的ARF; <br/>(d-1)所选台站在全球的分布;(d-2)18个台站叠加后所得的ARF<br/>Fig.2 Distribution of the selected stations in global subnet and the ARF of recordings of MW6.3 earthquake on Jun.15,1992 (a-1)distribution of 9 stations in the east of epicentre;(a-2)ARF of recordings of 9 stations in the east of epicentre; (b-1)distribution of 9 stations in the west of epicentre;(b-2)ARF of recordings of 9 stations in the west of epicentre; (c-1)distribution of the selected global stations;(c-2)ARF obtained by networking of 18 stations; (d-1)distribution of the selected global stations;(d-2)ARF obtained by stacking of 18 stations

图2 1992年6月15日MW6.3地震全球子台网所选台站分布及ARF
(a-1)震中以东9个台站的分布;(a-2)震中以东9个台站记录所得的ARF;
(b-1)震中以西9个台站的分布;(b-2)震中以西9个台站记录所得的ARF;
(c-1)所选台站在全球的分布;(c-2)18个台站同时组网所得的ARF;
(d-1)所选台站在全球的分布;(d-2)18个台站叠加后所得的ARF
Fig.2 Distribution of the selected stations in global subnet and the ARF of recordings of MW6.3 earthquake on Jun.15,1992 (a-1)distribution of 9 stations in the east of epicentre;(a-2)ARF of recordings of 9 stations in the east of epicentre; (b-1)distribution of 9 stations in the west of epicentre;(b-2)ARF of recordings of 9 stations in the west of epicentre; (c-1)distribution of the selected global stations;(c-2)ARF obtained by networking of 18 stations; (d-1)distribution of the selected global stations;(d-2)ARF obtained by stacking of 18 stations

图3 2000年6月7日MW6.4地震全球子台网所选台站分布及ARF<br/>(a-1)所选165个全球子台网的台站分布;(a-2)所选165个台站记录所得到的ARF; <br/>(b-1)进行台站权重筛选后的29个全球子台网的台站分布;(b-2)进行台站权重筛选后的<br/>29个台站记录所得到的ARF<br/>Fig.3 Distribution of the selected stations and ARF of recordings of the MW6.4 earthquake on Jun.7, 2000 (a-1)distribution of the selected 165 global stations;(a-2)ARF of recordings of 165 global stations;(b-1)distribution of 29 stations after station weight selection;(b-2)ARF of recordings of 29 stations after station weight selection

图3 2000年6月7日MW6.4地震全球子台网所选台站分布及ARF
(a-1)所选165个全球子台网的台站分布;(a-2)所选165个台站记录所得到的ARF;
(b-1)进行台站权重筛选后的29个全球子台网的台站分布;(b-2)进行台站权重筛选后的
29个台站记录所得到的ARF
Fig.3 Distribution of the selected stations and ARF of recordings of the MW6.4 earthquake on Jun.7, 2000 (a-1)distribution of the selected 165 global stations;(a-2)ARF of recordings of 165 global stations;(b-1)distribution of 29 stations after station weight selection;(b-2)ARF of recordings of 29 stations after station weight selection

图4 2003年9月21日MW6.7地震全球子台网所选台站分布及ARF<br/>(a-1)所选191个全球子台网的台站分布;(a-2)所选191个全球子台网记录所得到的ARF;(b-1)进行台<br/>站权重筛选后的45个全球子台网的台站分布;(b-2)进行台站权重筛选后的45个台站记录所得到的ARF。<br/>Fig.4 Distribution of the selected stations and ARF of recordings of MW6.7 earthquake on Sep.21, 2003 (a-1)distribution of the selected 191 global stations;(a-2)ARF of recordings of 191 global stations;(b-1)distribution of 45 stations after station weight selection;(b-2)ARF of recordings of 45 stations after station weight selection

图4 2003年9月21日MW6.7地震全球子台网所选台站分布及ARF
(a-1)所选191个全球子台网的台站分布;(a-2)所选191个全球子台网记录所得到的ARF;(b-1)进行台
站权重筛选后的45个全球子台网的台站分布;(b-2)进行台站权重筛选后的45个台站记录所得到的ARF。
Fig.4 Distribution of the selected stations and ARF of recordings of MW6.7 earthquake on Sep.21, 2003 (a-1)distribution of the selected 191 global stations;(a-2)ARF of recordings of 191 global stations;(b-1)distribution of 45 stations after station weight selection;(b-2)ARF of recordings of 45 stations after station weight selection

图5 1992年6月15日MW6.3地震所选台站的P波记录及MCCC波形相似度<br/>(a)所选用的18条未滤波的P波记录;(b)震中以东9个台站的MCCC波形相似度; <br/>(c)震中以西台站的MCCC波形相似度<br/>Fig.5 P wave recordings and MCCC values of MW6.3 earthquake on Jun.15, 1992 recorded by the selected stations(a)18 unfilted P wave records;(b)MCCC values of 9 stations located in the east of the epicenter; (c)MCCC values of 9 stations located in the west of the epicenter

图5 1992年6月15日MW6.3地震所选台站的P波记录及MCCC波形相似度
(a)所选用的18条未滤波的P波记录;(b)震中以东9个台站的MCCC波形相似度;
(c)震中以西台站的MCCC波形相似度
Fig.5 P wave recordings and MCCC values of MW6.3 earthquake on Jun.15, 1992 recorded by the selected stations(a)18 unfilted P wave records;(b)MCCC values of 9 stations located in the east of the epicenter; (c)MCCC values of 9 stations located in the west of the epicenter

图6 2000年6月7日MW6.4地震所选用的29个台站记录的未滤波的P波记录(a)及MCCC波形相似度(b)<br/>Fig.6 P wave unfilted recordings(a)and MCCC values(b)of MW6.4 earthquake on Jun.7, 2000 recorded by the selected 29 stations

图6 2000年6月7日MW6.4地震所选用的29个台站记录的未滤波的P波记录(a)及MCCC波形相似度(b)
Fig.6 P wave unfilted recordings(a)and MCCC values(b)of MW6.4 earthquake on Jun.7, 2000 recorded by the selected 29 stations

图7 2003年9月21日MW6.7地震所选用的45个台站记录的未滤波的P波记录(a)及MCCC波形相似度(b)<br/>Fig.7 P wave unfilted recordings(a)and MCCC values(b)of MW6.7 earthquake on Sep.21, 2003 recorded by the selected 45 stations

图7 2003年9月21日MW6.7地震所选用的45个台站记录的未滤波的P波记录(a)及MCCC波形相似度(b)
Fig.7 P wave unfilted recordings(a)and MCCC values(b)of MW6.7 earthquake on Sep.21, 2003 recorded by the selected 45 stations

图8 1992年6月15日MW6.3地震能量积累图<br/>(a-1)～(f-1)为相应窗长及频率对应的地震能量值随时间变化曲线图;(a-2)10 s窗长、低频<br/>(中心频率0.5 Hz);(b-2)10秒窗长、中频(中心频率1.0 Hz);( c-2)10 s窗长,高频(中心频率1.5 Hz); <br/>(d-2)20 s窗长、低频(中心频率0.5 Hz);(e-2)20 s窗长、中频(中心频率1.0 Hz);(f-2)20 s窗长,高频(中心频率1.5 Hz)<br/>Fig.8 Comulative beam of MW6.3 earthquake on Jun.15, 1992(a-1)～(f-1)are the curves of earthquake energy value changing with time by different window and frequency;(a-2)10 s window length, low frequency(the center frequency is 0.5 Hz);(b-2)10 s window length, middle frequency(the center frequency is 1.0 Hz);(c-2)10 s window length, high frequency(the center frequency is 1.5 Hz);(d-2)20 s window length, low frequency(the center frequency is 0.5 Hz);(e-2)20 s window length, middle frequency(the center frequencyis 1.0 Hz);(f-2)20 s window length, high frequency(the center frequency is 1.5 Hz)

图8 1992年6月15日MW6.3地震能量积累图
(a-1)～(f-1)为相应窗长及频率对应的地震能量值随时间变化曲线图;(a-2)10 s窗长、低频
(中心频率0.5 Hz);(b-2)10秒窗长、中频(中心频率1.0 Hz);( c-2)10 s窗长,高频(中心频率1.5 Hz);
(d-2)20 s窗长、低频(中心频率0.5 Hz);(e-2)20 s窗长、中频(中心频率1.0 Hz);(f-2)20 s窗长,高频(中心频率1.5 Hz)
Fig.8 Comulative beam of MW6.3 earthquake on Jun.15, 1992(a-1)～(f-1)are the curves of earthquake energy value changing with time by different window and frequency;(a-2)10 s window length, low frequency(the center frequency is 0.5 Hz);(b-2)10 s window length, middle frequency(the center frequency is 1.0 Hz);(c-2)10 s window length, high frequency(the center frequency is 1.5 Hz);(d-2)20 s window length, low frequency(the center frequency is 0.5 Hz);(e-2)20 s window length, middle frequency(the center frequencyis 1.0 Hz);(f-2)20 s window length, high frequency(the center frequency is 1.5 Hz)

图9 2000年6月7日MW6.4地震能量积累图<br/>(a-1)～(f-1)分别为相应窗长及频率对应的地震能量值随时间变化曲线图;(a-2)10 s窗长、低频(中心<br/>频率0.5 Hz);(b-2)10秒窗长、中频(中心频率1.0 Hz);( c-2)10 s窗长,高频(中心频率1.5Hz); <br/>(d-2)20 s窗长、低频(中心频率0.5 Hz);(e-2)20 s窗长、中频(中心频率1.0 Hz);(f-2)20 s窗长,高频(中心频率1.5 Hz)<br/>Fig.9 Comulative beam of MW 6.4 earthquake on Jun.7, 2000(a-1)～(f-1)are the curves of earthquake energy value changing with time by different window and frequency;(a-2)10 s window length, low frequency(the center frequency is 0.5 Hz);(b-2)10 s window length, middle frequency(the center frequency is 1.0 Hz);(c-2)10 s window length, high frequency(the center frequency is 1.5 Hz);(d-2)20 s window length, low frequency(the center frequency is 0.5 Hz);(e-2)20 s window length, middle frequency(the center frequency is 1.0 Hz);(f-2)20 s window length,high frequency(the center frequency is 1.5 Hz)

图9 2000年6月7日MW6.4地震能量积累图
(a-1)～(f-1)分别为相应窗长及频率对应的地震能量值随时间变化曲线图;(a-2)10 s窗长、低频(中心
频率0.5 Hz);(b-2)10秒窗长、中频(中心频率1.0 Hz);( c-2)10 s窗长,高频(中心频率1.5Hz);
(d-2)20 s窗长、低频(中心频率0.5 Hz);(e-2)20 s窗长、中频(中心频率1.0 Hz);(f-2)20 s窗长,高频(中心频率1.5 Hz)
Fig.9 Comulative beam of MW 6.4 earthquake on Jun.7, 2000(a-1)～(f-1)are the curves of earthquake energy value changing with time by different window and frequency;(a-2)10 s window length, low frequency(the center frequency is 0.5 Hz);(b-2)10 s window length, middle frequency(the center frequency is 1.0 Hz);(c-2)10 s window length, high frequency(the center frequency is 1.5 Hz);(d-2)20 s window length, low frequency(the center frequency is 0.5 Hz);(e-2)20 s window length, middle frequency(the center frequency is 1.0 Hz);(f-2)20 s window length,high frequency(the center frequency is 1.5 Hz)

图10 2003年9月21日MW6.7地震能量积累图<br/>(a-1)～(f-1)分别为相应窗长及频率对应的地震能量值随时间变化曲线图;(a-2)10 s窗长、低频(中心频率<br/>0.5 Hz);(b-2)10秒窗长、中频(中心频率1.0 Hz);( c-2)10 s窗长,高频(中心频率1.5Hz);(d-2)20 s窗长、<br/>低频(中心频率0.5 Hz);(e-2)20 s窗长、中频(中心频率1.0 Hz);(f-2)20 s窗长,高频(中心频率1.5 Hz)<br/>Fig.10 Comulative beam of MW 6.7 earthquake in Sep. 21, 2003(a-1)～(f-1)are the curves of earthquake energy value changing with time by different window and equency;(a-2)10 s window length, low frequency(the center frequency is 0.5 Hz);(b-2)10 s window length, middle frequency(the center frequency is 1.0 Hz);(c-2)10 s window length, high frequency(the center frequency is 1.5 Hz);(d-2)20 s window length, low frequency(the center frequency is 0.5 Hz);(e-2)20 s window length, middle frequency(the center frequency is 1.0 Hz); (f-2)20 s window length, high frequency(the center frequency is 1.5 Hz)

图10 2003年9月21日MW6.7地震能量积累图
(a-1)～(f-1)分别为相应窗长及频率对应的地震能量值随时间变化曲线图;(a-2)10 s窗长、低频(中心频率
0.5 Hz);(b-2)10秒窗长、中频(中心频率1.0 Hz);( c-2)10 s窗长,高频(中心频率1.5Hz);(d-2)20 s窗长、
低频(中心频率0.5 Hz);(e-2)20 s窗长、中频(中心频率1.0 Hz);(f-2)20 s窗长,高频(中心频率1.5 Hz)
Fig.10 Comulative beam of MW 6.7 earthquake in Sep. 21, 2003(a-1)～(f-1)are the curves of earthquake energy value changing with time by different window and equency;(a-2)10 s window length, low frequency(the center frequency is 0.5 Hz);(b-2)10 s window length, middle frequency(the center frequency is 1.0 Hz);(c-2)10 s window length, high frequency(the center frequency is 1.5 Hz);(d-2)20 s window length, low frequency(the center frequency is 0.5 Hz);(e-2)20 s window length, middle frequency(the center frequency is 1.0 Hz); (f-2)20 s window length, high frequency(the center frequency is 1.5 Hz)