1998～2003年伽师三次不同类型M_s6级地震震源破裂过程及短期内余震活动特征
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摘要
利用大量远场观测地震图反演了新疆伽师地区三次不同机制类型M_s6级地震的破裂过程.结果表明。1998年8月2日M_s6.1级地震破裂尺度小,破裂过程简单,最大滑动量为12 cm,主破裂过程持续时间为8 s.1998年8月27日M_s6.5地震破裂过程的空间分布反映出双侧破裂特征。主破裂过程在前13 s基本完成,最大滑动量为63 cm,破裂面上起始破裂点两侧的滑动矢量方向不同.2003年2月24日M_s6.8地震的破裂过程最为复杂,震源时间函数由两次上升时间组成,破裂一共持续了32 s,最大滑动量为32 cm.研究表明,余震主要发生在主震破裂图像中大滑动量区域的外围或滑动量变化梯度较大的区域,主震后短期内发生的余震震源机制解也与破裂面上断层的错动方向一致,表明余震的位置和机制与主震破裂所引起的应力重新分布有关.
By using the far field body waves,the temporal and spatial rupture process of 3 M_s 6.1 events with different focal mechanisms occurred in Jiashi,Xinjiang,from 1998 to 2003 were studied.The rupture pattern of Aug.2,1998,reveals that the rupture zone is small,the rupture process is simple and lasted about 8s,the maximum slip is 12cm.The rupture process of Aug. 27,1998,demonstrates a bilateral rupture characteristic,the process finished within 13s with the maximum slip of 63cm.The rupture process of M_s6.8 on Feb.24 2003 is the most complicated among them.Its source time function is composed of 2 rise periods,and totally lasted 32s,with the most slip 32cm.Our study reveals that aftershocks following the corresponding main shock occurred along the edge of area formed by large main shock slip on the fault plane,or on the area of slip rapidly decreased.Furthermore,aftershocks following the main shock within the first two weeks exhibit focal mechanisms coincident with the direction of the main shock slip,suggesting that the location and mechanism of aftershocks following the main shock are related with the stress redistribution after the main shock occurred.
By using the far field body waves,the temporal and spatial rupture process of 3 M_s 6.1 events with different focal mechanisms occurred in Jiashi,Xinjiang,from 1998 to 2003 were studied.The rupture pattern of Aug.2,1998,reveals that the rupture zone is small,the rupture process is simple and lasted about 8s,the maximum slip is 12cm.The rupture process of Aug. 27,1998,demonstrates a bilateral rupture characteristic,the process finished within 13s with the maximum slip of 63cm.The rupture process of M_s6.8 on Feb.24 2003 is the most complicated among them.Its source time function is composed of 2 rise periods,and totally lasted 32s,with the most slip 32cm.Our study reveals that aftershocks following the corresponding main shock occurred along the edge of area formed by large main shock slip on the fault plane,or on the area of slip rapidly decreased.Furthermore,aftershocks following the main shock within the first two weeks exhibit focal mechanisms coincident with the direction of the main shock slip,suggesting that the location and mechanism of aftershocks following the main shock are related with the stress redistribution after the main shock occurred.
引文
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[3]单新建，何玉梅，朱燕等．伽师强震群震源破裂特征的初步分析．地球物理学报，2002，45(3)：416～425 Shan X J,He Y M,Zhu Y,et al.A primary analysis on rupture characteristics of Jiashi strong earthquake swarm. Chinese J.Geophys.(in Chinese),2002,45(3):416～425
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[5]张先康，赵金仁，张成科等．帕米尔东北侧地壳结构研究．地球物理学报，2002，45(5)：665～671 Zhang X K,Zhao J R,Zhang C K,et al.Crustal structure at the North-east side of the Pamirs.Chinese J.Geophys.(in Chinese),2002,45(5):665～671
[6]王琪，丁国瑜，乔学军等．天山现今地壳快速缩短与南北地块的相对运动．科学通报，2000，45(14)：1543～1547 Wang Q,Ding G Y,Qiao X J,et al.,The contemporary crustal shortening of Tienshan and its movement relative to the South-North block.Chinese Science Bulletin(in Chinese).2000,45(14):1543～1547
[7]张培震，王琪，马宗晋．中国大陆现今构造运动的GPS速度场与活动地块．地学前缘，2002，9(2)；430～441 Zhang P Z,Wang Q,Ma Z J.GPS velocity field and active crustal blocks of contemporary tectonic deformation in continental China.Earth Science Frontiers(in Chinese), 2002,9(2),430～441
[8]Kikuchi M,Kanamori H.Inversion of complex body waves-Ⅲ.Bull.Seism.Soc.Am.,1991,81:2335～2350
[9]赵翠萍．1997～2003年新疆伽师震源区特征的地震学方法研究[博士论文]．北京：中国地震局地球物理研究所．2006 Zhao C P,Seismological studies on the characteristics of Jiashi Source Region from 1997 to 2003.[Ph.D.thesis]. Beijing:Institute of Geophysics,Chinese Earthquake Administration,2006
[10]赵翠萍，陈章立，郑斯华等．伽师震源区中等强度地震矩张量反演及应力场特征．地球物理学报，2008．51(3)：782～792 Zhao C P,Chen Z L,Zheng S H,et al.Moment inversion of moderate-sized earthquakes and the locally perturbed stress field in the Jiashi source region.Chinese J.Geophys.,2008, 51(3):782～792
[11]Doser D I,Kamamori H.Depth of seismicity in the Imperial Valley region(1977～1983)and its relationship to heat flow, crustal structure,and the October 15,1979,earthquake.J. Geophys.Res.,1986,91:675～688
[12]Hartzell S H,Heaton T H.Teleseismic time functions for large,shallow subduction zone earthquakes.Bull.Seism. Soc.Am.,1985,75,965～1004
[13]King G C,Stein S,Lin J.Static stress changes and the triggering of earthquakes.Bull.Seism.Soc.Am.,1994,84 (3):935～953
[14]Bouchon M.The state of stress on some faults of the San Andreas system as inferred from near-field strong motion data.J.Geophys.Res.,1997,102:11731～11744
[15]Fletcher J B,Guateri M.Stress drop for three M4.3～4.7 (1992～1994)Parkfield,CA,earthquake.Geophys.Res. Lett.,1999,26(15):2295～2298
[16]Zobin V M,Levina V I.The rupture process of the M_w 7.8 Cape Kronotsky,Kamchatka,earthquake of 5 December 1997 and its relationship to foreshocks and aftershocks.Bull. Seism.Soc.Am.,2001,91(6):1619～1628
[2]王卫民，李丽，赵连锋等．2003年2月24日新疆伽师M_s6．5级地震震源破裂过程研究．地球物理学报，2005，48 (2)：343～351 Wang W M,Li L,Zhao L F,et al.Rupture process of Jiashi, Xinjiang earthquake(M_s 6.15)of Feb.24,2003.Chinese J. Geophys.(in Chinese).2005.48(2):343～351
[3]单新建，何玉梅，朱燕等．伽师强震群震源破裂特征的初步分析．地球物理学报，2002，45(3)：416～425 Shan X J,He Y M,Zhu Y,et al.A primary analysis on rupture characteristics of Jiashi strong earthquake swarm. Chinese J.Geophys.(in Chinese),2002,45(3):416～425
[4]刘启元，陈九辉，李顺成等．新疆伽师强震群区三维地壳上地幔S波速度结构及其地震成因的探讨．地球物理学报．2000，43(3)：356～365 Liu Q Y,Chen J H,Li S C,et al.Passive seismic experiment in Xinjiang Jiashi strong earthquake region and discussion on its seismic genesis.Chinese J.Geophys.(in Chinese),2000, 43(3):356～365
[5]张先康，赵金仁，张成科等．帕米尔东北侧地壳结构研究．地球物理学报，2002，45(5)：665～671 Zhang X K,Zhao J R,Zhang C K,et al.Crustal structure at the North-east side of the Pamirs.Chinese J.Geophys.(in Chinese),2002,45(5):665～671
[6]王琪，丁国瑜，乔学军等．天山现今地壳快速缩短与南北地块的相对运动．科学通报，2000，45(14)：1543～1547 Wang Q,Ding G Y,Qiao X J,et al.,The contemporary crustal shortening of Tienshan and its movement relative to the South-North block.Chinese Science Bulletin(in Chinese).2000,45(14):1543～1547
[7]张培震，王琪，马宗晋．中国大陆现今构造运动的GPS速度场与活动地块．地学前缘，2002，9(2)；430～441 Zhang P Z,Wang Q,Ma Z J.GPS velocity field and active crustal blocks of contemporary tectonic deformation in continental China.Earth Science Frontiers(in Chinese), 2002,9(2),430～441
[8]Kikuchi M,Kanamori H.Inversion of complex body waves-Ⅲ.Bull.Seism.Soc.Am.,1991,81:2335～2350
[9]赵翠萍．1997～2003年新疆伽师震源区特征的地震学方法研究[博士论文]．北京：中国地震局地球物理研究所．2006 Zhao C P,Seismological studies on the characteristics of Jiashi Source Region from 1997 to 2003.[Ph.D.thesis]. Beijing:Institute of Geophysics,Chinese Earthquake Administration,2006
[10]赵翠萍，陈章立，郑斯华等．伽师震源区中等强度地震矩张量反演及应力场特征．地球物理学报，2008．51(3)：782～792 Zhao C P,Chen Z L,Zheng S H,et al.Moment inversion of moderate-sized earthquakes and the locally perturbed stress field in the Jiashi source region.Chinese J.Geophys.,2008, 51(3):782～792
[11]Doser D I,Kamamori H.Depth of seismicity in the Imperial Valley region(1977～1983)and its relationship to heat flow, crustal structure,and the October 15,1979,earthquake.J. Geophys.Res.,1986,91:675～688
[12]Hartzell S H,Heaton T H.Teleseismic time functions for large,shallow subduction zone earthquakes.Bull.Seism. Soc.Am.,1985,75,965～1004
[13]King G C,Stein S,Lin J.Static stress changes and the triggering of earthquakes.Bull.Seism.Soc.Am.,1994,84 (3):935～953
[14]Bouchon M.The state of stress on some faults of the San Andreas system as inferred from near-field strong motion data.J.Geophys.Res.,1997,102:11731～11744
[15]Fletcher J B,Guateri M.Stress drop for three M4.3～4.7 (1992～1994)Parkfield,CA,earthquake.Geophys.Res. Lett.,1999,26(15):2295～2298
[16]Zobin V M,Levina V I.The rupture process of the M_w 7.8 Cape Kronotsky,Kamchatka,earthquake of 5 December 1997 and its relationship to foreshocks and aftershocks.Bull. Seism.Soc.Am.,2001,91(6):1619～1628
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