利用GDSN宽频带资料研究青海地区1988～1990年强震的震源过程
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摘要
1988至1990年，青海地区发生了4次震级大于6．0的强震。利用GDSN宽频带波形资料，通过波形模拟，结合地质构造的背景资料对这几次地震进行了震源破裂和发震构造背景的研究。使用台站的准震源时间函数（qSTE）和准时间差（qTD）的分析方法，对震源的复杂性进行了讨论。1988年11月5日沱沱河沿Ms6．3地震是一个由两次子破裂组成的复杂震源过程的地震；1990年1月14日茫崖Ms6．1地震发生于重力异常带的交汇处，破裂扩展方面与断层走向一致；1990年4月26日共和Ms6．9与mb6．3地震的震源过程更为复杂，Ms6．9地震由两次子破裂组成，约30s后发生的mb6．3地震是一个独立于Ms6．9地震的大破裂。本文的研究从震源分析的角度进一步支持了青藏高原东北部构造应力的压力轴为接近水平的NE向，随着向青藏高原北部的推移，其构造应力的压力轴逆时针转为接近水平的NEE或N－S向的结论。
From 1888 to 1990, four strong earthquakes which magnitudes were larger than 6.0 ocurred in Qinghai province. Using the GDSN broadband waveform data, both the seismic source rupture features and seismogenic tectonic background of these eaxthquakes are studied combining with geologic data by waveform modelling. Specially, a method of station quasi - source time function (qSTE) and quasi - the difference (qTD) is used to dicuss the complexity of source process. The Ms6.3 Totoheyan earthquake on 5th November 1988 is an event of complicated source process composed of two subevents. The Ms6.1 Mangya earthquake on 14th January 1990 is locted at a convergence of gravity anomaly zones, which rupture propagation direction corresponds with fault direction. It is more complicated for two Ms6.9 and Ms6.3 Gonghe earthquakes on 26th April 1990, in which the former is composed of two subevents and the latter, which occurred for about 30 seconds late than the former, is a large independent repture.According to the source analysis, it is further suggested to the conclusion that the pressure axies of the tectonic stress field in the northeast of Qinghai-Xizang plateau is oriental to NE-SW close to horizontal direction, and with the evolvemen toward the north of Qinghai-Xizang plateau it is changed anticlockwisely to NEE - SSW or N - S close to horizontal direction.
From 1888 to 1990, four strong earthquakes which magnitudes were larger than 6.0 ocurred in Qinghai province. Using the GDSN broadband waveform data, both the seismic source rupture features and seismogenic tectonic background of these eaxthquakes are studied combining with geologic data by waveform modelling. Specially, a method of station quasi - source time function (qSTE) and quasi - the difference (qTD) is used to dicuss the complexity of source process. The Ms6.3 Totoheyan earthquake on 5th November 1988 is an event of complicated source process composed of two subevents. The Ms6.1 Mangya earthquake on 14th January 1990 is locted at a convergence of gravity anomaly zones, which rupture propagation direction corresponds with fault direction. It is more complicated for two Ms6.9 and Ms6.3 Gonghe earthquakes on 26th April 1990, in which the former is composed of two subevents and the latter, which occurred for about 30 seconds late than the former, is a large independent repture.According to the source analysis, it is further suggested to the conclusion that the pressure axies of the tectonic stress field in the northeast of Qinghai-Xizang plateau is oriental to NE-SW close to horizontal direction, and with the evolvemen toward the north of Qinghai-Xizang plateau it is changed anticlockwisely to NEE - SSW or N - S close to horizontal direction.
引文
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2Zhao W J, Nelson K D Project INDEPTH Team.Deep seismic reflection evidence for continental underthrusting beneath southem Tibet. Nature, 1992,366, 557-559
3曾融生,孙为国.青藏高原及其邻区的地震活动性和震源机制以及高原物质东流的讨论.地震学报, 1992, 14(增刊): 534-563
4郑柄华,向光中,蒋能强.青藏地区岩石图动力学特征.见:马杏垣主编.中国岩石图动力学地图集.北京:中国地图出版社,1989.68
5刘光勋,马廷著,黄佩玉,白玉芹,主要活动断裂及其现分运动.见:马杏垣主编.中国岩石圈动力学地图集.北京:中国地图出版社,1989.17
6Choy G L, Bowman J. Rupture process of a multiple main shock sequence: analysis of teleseismic, local and field observations of the tennant creek,Australia, earthquake of January 22.J. Geophys, Res., 1990,95, 6867-6882
7Choy G L, Cormier V F. Derect measurement of the mantle attenuation operator from broadband P, S waveforms, J. Geophys, Res,1986, 91, 7326-7342
8高原,吴忠良.1993年11月13日堪察加大地震的破裂过程及其构造意义.地球物理学报,1995,38(1):55-63
9周蕙兰.青海省西南部西捷与伦伦河沿之间1988年11月5日强震的震源机制.中国地震,1995,11(1):84-91
10曾秋生.茫崖-花土沟地区的地震地质特征.高原地震,1991,3(3):1-11
11青海省地震局大震考察队.茫崖6.7缓地震考察.高原地震,1990,2(2):54-61
12高原.较大地震破裂尺度的一种简单估计.地震,1996,16(4):377-383
13邹文卫,马文静.柴达木西部地区地球物理场特征及地震活动性分析.高原地震, 1991,3(3): 12-23
14伍建平,陈玉华,林彤.青海地震构造.见:马杏垣主编.中国岩石图动力学地图集.北京:中国地图出版社,1989.55
15张瑞斌,陈玉华.共和盆地构植背景及发震构造探讨.高原地震,1994,6(4):39-44
16曾秋生.一九九0年四月二十六日青海省共和、兴海间6.9缓地震概况.高原地震,1990,2(3):3-12
17陈运泰,赵明,李旭,许力生.青海共和地震震源过程的复杂性,见:陈运菜,等主编:中国固体地球物理学进展.北京:海洋出版社,1994.287-304
18Chen Y T, XU L S, Li X, Zhao M. Source process of the 1990 Gonghe China, earthquake and tectonic stress field in the northeastern Qinghai-Xizang(Tibetan) Plateau, Pageoph, 1996, 146(3/4):697-715
19Avouac J P, Tapponnier P. Kinematic model ofactive deformation in Central Asia. Geophys, Res. Lett., 1993, 20: 895-898
20Xu Z H, Wang S Y, Huang Y R, Cao A J.TECTONIC STRESS FIELD OF China inferred from a large number of small earthquakes. J. Geophys.Res., 1992, 97(B8):11867-11877
2Zhao W J, Nelson K D Project INDEPTH Team.Deep seismic reflection evidence for continental underthrusting beneath southem Tibet. Nature, 1992,366, 557-559
3曾融生,孙为国.青藏高原及其邻区的地震活动性和震源机制以及高原物质东流的讨论.地震学报, 1992, 14(增刊): 534-563
4郑柄华,向光中,蒋能强.青藏地区岩石图动力学特征.见:马杏垣主编.中国岩石图动力学地图集.北京:中国地图出版社,1989.68
5刘光勋,马廷著,黄佩玉,白玉芹,主要活动断裂及其现分运动.见:马杏垣主编.中国岩石圈动力学地图集.北京:中国地图出版社,1989.17
6Choy G L, Bowman J. Rupture process of a multiple main shock sequence: analysis of teleseismic, local and field observations of the tennant creek,Australia, earthquake of January 22.J. Geophys, Res., 1990,95, 6867-6882
7Choy G L, Cormier V F. Derect measurement of the mantle attenuation operator from broadband P, S waveforms, J. Geophys, Res,1986, 91, 7326-7342
8高原,吴忠良.1993年11月13日堪察加大地震的破裂过程及其构造意义.地球物理学报,1995,38(1):55-63
9周蕙兰.青海省西南部西捷与伦伦河沿之间1988年11月5日强震的震源机制.中国地震,1995,11(1):84-91
10曾秋生.茫崖-花土沟地区的地震地质特征.高原地震,1991,3(3):1-11
11青海省地震局大震考察队.茫崖6.7缓地震考察.高原地震,1990,2(2):54-61
12高原.较大地震破裂尺度的一种简单估计.地震,1996,16(4):377-383
13邹文卫,马文静.柴达木西部地区地球物理场特征及地震活动性分析.高原地震, 1991,3(3): 12-23
14伍建平,陈玉华,林彤.青海地震构造.见:马杏垣主编.中国岩石图动力学地图集.北京:中国地图出版社,1989.55
15张瑞斌,陈玉华.共和盆地构植背景及发震构造探讨.高原地震,1994,6(4):39-44
16曾秋生.一九九0年四月二十六日青海省共和、兴海间6.9缓地震概况.高原地震,1990,2(3):3-12
17陈运泰,赵明,李旭,许力生.青海共和地震震源过程的复杂性,见:陈运菜,等主编:中国固体地球物理学进展.北京:海洋出版社,1994.287-304
18Chen Y T, XU L S, Li X, Zhao M. Source process of the 1990 Gonghe China, earthquake and tectonic stress field in the northeastern Qinghai-Xizang(Tibetan) Plateau, Pageoph, 1996, 146(3/4):697-715
19Avouac J P, Tapponnier P. Kinematic model ofactive deformation in Central Asia. Geophys, Res. Lett., 1993, 20: 895-898
20Xu Z H, Wang S Y, Huang Y R, Cao A J.TECTONIC STRESS FIELD OF China inferred from a large number of small earthquakes. J. Geophys.Res., 1992, 97(B8):11867-11877
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