2010年玉树M_S7.1地震及其余震的双差定位研究
摘要
2010年4月14日玉树MS7.1大地震发生后,周边固定观测台网和流动台站记录到大量余震事件,由于受台站分布、速度结构研究不足以及震相拾取可靠性等因素的影响,台网常规定位结果精度较低,很难从中获得有关余震活动时空分布特征和余震活动趋势的正确认识.本文利用固定台站远震波形数据,采用接收函数H-K扫描和反演对震区附近地下速度结构进行研究,获得了震区附近下方的结构特征.同时利用玉树地震序列的震相数据,采用双差法对地震序列进行重新定位.定位结果显示,玉树地震的主震深度为13km,余震序列主要沿甘孜-玉树断裂北西西向分布,长度约100km,多数余震集中分布在5～20km的范围内.结合地下速度结构,可推断此次地震主要错断了上地壳的高速地层.在断层西段(33.3°N,96.2°E)附近,余震几乎呈现垂直向下的柱状分布,推断此处出现粉碎性破裂且破裂从地下25km处贯穿到地表.
引文
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24Zheng X,Yao Z,Liang J,et al.The role played and opportunities provided by IGP DMC of China National Seismic Network in Wenchuan earthquake disaster relief and researches.Bull Seismol Soc Amer,2010,100:2866-2872
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30刘超,许力生,陈运泰.2010年4月14日青海玉树地震快速矩张量解.地震学报,2010,32:366-368
2杨智娴,陈运泰,郑月军,等.双差地震定位法在我国中西部地区地震精确定位中的应用.中国科学D辑:地球科学,2003,33(增刊):129-134
3朱艾斓,徐锡伟,胡平,等.首都圈地区b值随震源深度的变化:对地震成核的意义.中国科学D辑:地球科学,2005,50:788-792
4朱艾斓,徐锡伟,周永胜,等.川西地区小震重新定位及其活动构造意义.科学通报,2005,48:629-636
5黄媛,杨建思,张天中.2003年新疆巴楚-伽师地震序列的双差法重新定位研究.地球物理学报,2006,49:162-169
6黄媛,吴建平,张天中,等.汶川8.0级大地震及其余震序列重定位研究.中国科学D辑:地球科学,2008,38:1242-1249
7GalvéA,Hirn A,Jiang M,et al.Modes of raising northeastern Tibet probed by explosion seismology.Earth Planet Sci Lett,2002,203:35-43
8GalvéA,Jiang M,Hirn A,et al.Explosion seismic P and S velocity and attenuation constraints on the lower crust of the North-Central Tibetan Plateau,and comparison with South Tibet-Himalayas:Implications on composition,mineralogy,temperature,and tectonic evolution.Tectonophysics,2006,412:141-157
9Jiang M,GalvéA,Hirn A,et al.Crustal thickening and variations in architecture from the Qaidam basin to the Qang Tang(north-central Tibetan Plateau),from wide-angle reflection seismology.Tectonophysics,2006,412:121-140
10Vergne J,Wittlinger G,Hui Q,et al.Seismic evidence for stepwise thickening of the crust across the NE Tibetan plateau.Earth Planet Sci Lett,2002,203:25-33
11Langston C.Structure under Mount Rainier,Washington,inferred from teleseismic body waves.J Geophys Res,1979,84:4749-4762
12Owens T J,Zandt G,Taylor S R.Seismic evidence for an ancient rift beneath the Cumberland Plateau,Tennessee:A detailed analysis of broadband teleseismic P waveforms.J Geophys Res,1984,89:7783-7795
13Zhu L P.Crustal structure across the San Andreas Fault,southern California from teleseismie converted waves.Earth Planet Sci Lett,2000,179:183-190
14Ai Y,Zheng T.The upper mantle discontinuity structure beneath eastern China.Geophys Res Lett,2003,30:2089,doi:10.1029/2003GL017678
15Zhu L,Owens T J,Randall G E.Lateral variation in crustal structure of the northern Tibetan Plateau inferred from teleseismic receiver functions.Bull Seismol Soc Amer,1995,85:1531-1540
16刘启元,李顺成,沈扬,等.延怀盆地及其邻区地壳上地幔速度结构的宽频带地震台阵研究.地球物理学报,1997,40:763-772
17刘启元,Kind R,陈九辉,等.大别造山带壳幔界面的断错结构和壳内低速体.中国科学D辑:地球科学,2005,35:304-313
18吴建平,明跃红,王椿镛.云南数字地震台站下方的S波速度结构研究.地球物理学报,2001,44:228-237
19Wu Q,Li Y,Zhang R,et al.Wavelet modelling of broad-band receiver functions.Geophys J Int,2007,170:534-544
20汪一鹏.青藏高原活动构造基本特征.见:活动断裂编委会.活动断裂研究(6).北京:地震出版社,l998
21中国科学院青藏高原综合科学考察队.青藏高原地质构造.北京:科学出版社,1982.71-90
22吴珍汉,叶培盛,胡道功,等.青藏高原腹地的地壳变形与构造地貌形成演化过程.北京:地震出版社,2003
23刁桂苓,王晓山,高国英,等.以震源机制类型划分汶川、玉树地震构造块体归属.地球物理学报,2010,53:1778-1783
24Zheng X,Yao Z,Liang J,et al.The role played and opportunities provided by IGP DMC of China National Seismic Network in Wenchuan earthquake disaster relief and researches.Bull Seismol Soc Amer,2010,100:2866-2872
25吴庆举,田小波,张乃铃,等.计算台站接收函数的最大熵谱反褶积方法.地震学报,2003,25:382-389
26Kennent B L N.Seismic Wave Propagation in Stratified Media.New York:Cambridge University Press,1983
27张勇,许力生,陈运泰.2010年青海玉树地震震源过程.中国科学:地球科学,2010,40:819-821
28刘云华,单新建,屈春燕,等.青海玉树Ms7.1级地震地表形变场特征研究.中国科学:地球科学,2010,40:1310-1320
29Liu C,Xu L S,Chen Y T.IGP-CEA moment tensor solution.2012.http://ddsep.cea-igp.ac.cn/EQ_Events_en/2010/201005290229A/M
30刘超,许力生,陈运泰.2010年4月14日青海玉树地震快速矩张量解.地震学报,2010,32:366-368
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