利用阿拉斯加台阵资料分析2008年汶川大地震的破裂过程
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摘要
2008年5月12日,四川省汶川县发生M_S8.0地震.我们利用美国阿拉斯加区域台网的邵分宽频带地震台构成广义台阵,应用非平面波台阵技术——迁移叠加方法,获得了这次地震的高频(>0.1 Hz)能量辐射源随时间和空间变化的图像.图像表明,这次地震破裂从震中开始向北东方向扩展约300 km,震源过程至少长达90 s,平均破裂速度为3.4 km/s;整个过程可分为两大阶段,前段持续时间50s,破裂长度约110 km,破裂传播的平均速度为2.2km/s,后段持续时间约40 s,长度约190 km,平均破裂速度为4.8 km/s.这意味着地震过程的后期似乎发生了超S波破裂,而且后段很可能为前段动态触发所致.
On 12th of May, 2008, an M_S8. 0 earthquake occurred in Wenchuan county, Sichuan province of China. We configured a generalized array with the broadband seismic stations of the Alaska Regional Network,USA, and imaged the temporal and spatial variation of high-frequency (>0. 1 Hz) energy radiation sources by means of one of the non-plane wave array techniquesmigration stacking technique. The image shows that the earthquake faulting initiated at the instrumental epicenter and extended north-eastwards about 300 km, the whole rupture process lasted for at least 90s, and the average rupture speed was about 3. 4 km/s. The whole process may be divided into two major periods. The first period is 50 s and in this period the rupture propagated about 110 km, with an average rupture speed of 2. 2 km/s; the other period is 40 s and in this period the rupture propagated about 190 km, with an average speed of 4. 8 km/s. It seems that supershear rupture appeared in the later process of the earthquake, and the second segment might be dynamically trigged by the first one.
On 12th of May, 2008, an M_S8. 0 earthquake occurred in Wenchuan county, Sichuan province of China. We configured a generalized array with the broadband seismic stations of the Alaska Regional Network,USA, and imaged the temporal and spatial variation of high-frequency (>0. 1 Hz) energy radiation sources by means of one of the non-plane wave array techniquesmigration stacking technique. The image shows that the earthquake faulting initiated at the instrumental epicenter and extended north-eastwards about 300 km, the whole rupture process lasted for at least 90s, and the average rupture speed was about 3. 4 km/s. The whole process may be divided into two major periods. The first period is 50 s and in this period the rupture propagated about 110 km, with an average rupture speed of 2. 2 km/s; the other period is 40 s and in this period the rupture propagated about 190 km, with an average speed of 4. 8 km/s. It seems that supershear rupture appeared in the later process of the earthquake, and the second segment might be dynamically trigged by the first one.
引文
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[8] Rost S, Thomas C. Array seismology: methods and applications. Rev. Geophys. , 2002, 40(3) : 1-27
[9] 杜海林.2004年苏门答腊-安达曼大地震能量辐射源的时间域台阵技术分析[硕士论文].北京:中国地震局地球物理研究所,2007 Du H L. Analysis of the energy radiation sources of the 2004 Sumatra-Andaman Earthquake using time-domain array techniques [M. S. thesis] (in Chinese). Beijing: Institute of Geophysics, China Earthquake Administration, 2007
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[12] Kruger F, Ohrnberger M. Tracking the rupture of the M_w = 9． 3 Sumatra earthquake over 1150 km at teleseismic distance. Nature, 2005, 435:937-939
[13] Du H L, Xu L S, Chen Y T, et al. Tracking the highfrequency energy radiation sources of the 2004 Sumatra-Andaman M_w9． 0 earthquake using the short-period seismic data:preliminary result. In: CHEN Y T ed. Advances in Geosciences, 9: Solid Earth, (SE), Singapore: World Scientific Publishing Co. , 2007． 3-11
[14] 许力生,杜海林,张红霞等.2007年9月苏门答腊岛近海三次大地震能量辐射源时空特征.科学通报,2008,53(17) :2085-2090 Xu L S, Du H L, Zhang H X, et al. Spatio-temporal characteristics of the energy radiation sources of the three earthquakes near Sumatra Island in September 2007． Chinese Science Bulletin , 2008, 53(15) :2364-2370
[15] Schweitzer J, Fyen J, Mykkeltveit S, et al. Seismic Arrays. In:Bormann P ed. New Manual of Seismological Observatory Practice. Germany:GeoForschungsZentrum Potsdam, 2002． Chapter 9
[16] 赵珠,范军,郑斯华等.龙门山断裂带地壳速度结构和震源位置的精确修订.地震学报,1997,19(6) :615-622 Zhao Z, Fan J, Zheng S H, et al. Crustal structure and accurate hypocenter determination along Longmenshan fault zone. Acta Seismological Sinica,1997, 10(6) :761-768
[2] 陈国光,计凤吉,周荣军等.龙门山断裂带第四纪活动性分段的初步研究.地震地质,2007,29(3) :657-673 Chen G G, Ji F J, Zhou R J, et al. Primary research of activity segmentation of Longmenshan fault zone since latequaternary. Seismology and Geology (in Chinese) , 2007,29 (3) :657-673
[3] 张培震,徐锡伟,闻学泽等.2008年汶川8． O级地震发震断裂的滑动速率、复发周期和构造成因.地球物理学报,2008,51(4) :1066-1073 Zhang P Z, Xu X W, Wen X Z, et al. Slip rates and recurrence intervals of the Longmen Shan active fault zone, and tectonic implications for the mechanism of the May 12 Wenchuan earthquake, 2008, Sichuan, China. Chinese J.Geophys.(in Chinese), 2008,51(4) ,1066-1073
[4] 徐锡伟,闻学泽,叶建青等.汶川M_s8． 0地震地表破裂带及其发震构造.地震地质,2008,30(3) :597-629 Xu X W, Wen X Z, Ye J Q, et al. The M_s8． 0 Wenchan earthquake surface ruptures and its seismogenic structure.Seismology and Geology (in Chinese), 2008, 30(3) :597-629
[5] 马保起,张世民,田勤俭.汶川8． O级地震地表破裂带.第四纪研究,2008,28(4) :513-517 Ma B Q, Zhang S M, Tian Q J. The surface rupture of Wenchuan earthquake (M8． 0) , Quaternary Sciences (in Chinese), 2008, 28(4) :513-517
[6] 张勇,冯万鹏,许力生等.2008年汶川大地震的时空破裂 过程.中国科学:D辑,2009,52(2) :145-154 Zhang Y, Feng W P, Xu L S, et al. Spatio-temporal rupture process of the 2008 great Wenchuan earthquake. Science in China (Series D) ,2009 ,52(2) :45-154
[7] 王卫民,赵连锋,李娟等.四川汶川8． 0级地震震源过程.地球物理学报,2008,51(5) :1403-1410 Wang W M, Zhao L F, Li J, et al. Rupture process of the M_s8． 0 Wenchuan earthquake of Sichuan, China. Chinese J. Geophys. (in Chinese), 2008,51(5) :1403-1410
[8] Rost S, Thomas C. Array seismology: methods and applications. Rev. Geophys. , 2002, 40(3) : 1-27
[9] 杜海林.2004年苏门答腊-安达曼大地震能量辐射源的时间域台阵技术分析[硕士论文].北京:中国地震局地球物理研究所,2007 Du H L. Analysis of the energy radiation sources of the 2004 Sumatra-Andaman Earthquake using time-domain array techniques [M. S. thesis] (in Chinese). Beijing: Institute of Geophysics, China Earthquake Administration, 2007
[10] Kennett B L N, Engdahl E R. Travel times for global earthquake location and phase identification. Geophys. J. Int. , 1991, 105:429-465
[11] Ishii M, Shearer P M, Houston H. Extend, duration and speed of the 2004 Sumatra-Andaman earthquake imaged by the Hi-Net array. Nature, 2005, 435:933-936
[12] Kruger F, Ohrnberger M. Tracking the rupture of the M_w = 9． 3 Sumatra earthquake over 1150 km at teleseismic distance. Nature, 2005, 435:937-939
[13] Du H L, Xu L S, Chen Y T, et al. Tracking the highfrequency energy radiation sources of the 2004 Sumatra-Andaman M_w9． 0 earthquake using the short-period seismic data:preliminary result. In: CHEN Y T ed. Advances in Geosciences, 9: Solid Earth, (SE), Singapore: World Scientific Publishing Co. , 2007． 3-11
[14] 许力生,杜海林,张红霞等.2007年9月苏门答腊岛近海三次大地震能量辐射源时空特征.科学通报,2008,53(17) :2085-2090 Xu L S, Du H L, Zhang H X, et al. Spatio-temporal characteristics of the energy radiation sources of the three earthquakes near Sumatra Island in September 2007． Chinese Science Bulletin , 2008, 53(15) :2364-2370
[15] Schweitzer J, Fyen J, Mykkeltveit S, et al. Seismic Arrays. In:Bormann P ed. New Manual of Seismological Observatory Practice. Germany:GeoForschungsZentrum Potsdam, 2002． Chapter 9
[16] 赵珠,范军,郑斯华等.龙门山断裂带地壳速度结构和震源位置的精确修订.地震学报,1997,19(6) :615-622 Zhao Z, Fan J, Zheng S H, et al. Crustal structure and accurate hypocenter determination along Longmenshan fault zone. Acta Seismological Sinica,1997, 10(6) :761-768
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