2008年于田Ms7.3地震前重力场动态变化特征分析
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摘要
基于1998年以来的中国大陆流动重力网观测数据,分析2008年3月新疆于田7.3级地震前区域重力场动态变化的演化特征。结果表明:区域重力场动态演化图像反映了该地震孕育的中长期(2～10年)基本信息;该地震孕育时的显著重力标志为持续多年的正重力变化(上升)和较大规模的重力变化梯级带,前者有利于地震能量的不断积累,后者有利于地震破裂的发生;该地震孕育过程中相关重力场变化呈增大-加速增大-减速增大的过程,与1976年唐山7.8级地震具类似特征;与该地震有关的多年(8年)最大累积重力变化达200×10-8ms-2。
On the basis of the data and results of the repeated gravity observation network in Chinese mainland since 1998,the evolution characteristics of dynamic gravity field changes in the seismogenic region before Yutian Ms7.3 earthquake in Mar,2008 has been analyzed and summarized.The dynamic evolution images of regional gravity field reflects the middle-long term(two to ten years)essential information during the earthquake preparation.The notable gravity symbols of the earthquake preparation are positive gravity change(rise)lasted for many years and relatively large-scale gradient zone of gravity change that the former is in favor of continuous accumulation of seismic energy and the latter makes for occurrence of seismic rupture.The related gravity change during the process of the earthquake preparation have the characteristics:increase-accelerated increase-decelerated increas which is similar to that of Tangshan Ms7.8 earthquake in 1976.The maximum accumulative gravity change related to the earthquake can reach 200×10-8ms-2.
On the basis of the data and results of the repeated gravity observation network in Chinese mainland since 1998,the evolution characteristics of dynamic gravity field changes in the seismogenic region before Yutian Ms7.3 earthquake in Mar,2008 has been analyzed and summarized.The dynamic evolution images of regional gravity field reflects the middle-long term(two to ten years)essential information during the earthquake preparation.The notable gravity symbols of the earthquake preparation are positive gravity change(rise)lasted for many years and relatively large-scale gradient zone of gravity change that the former is in favor of continuous accumulation of seismic energy and the latter makes for occurrence of seismic rupture.The related gravity change during the process of the earthquake preparation have the characteristics:increase-accelerated increase-decelerated increas which is similar to that of Tangshan Ms7.8 earthquake in 1976.The maximum accumulative gravity change related to the earthquake can reach 200×10-8ms-2.
引文
1祝意青,徐云马,梁伟锋,2008年新疆于田Ms7.3地震的中期预测[J].大地测量与地球动力学,2008,(5):13-15.(Zhu Yiqing,Xu Yunma and Liang Weifeng.Medium-term prediction of Yutian,XinjiangMs7.3earthquake in2008[J].Journal of geodesy and geodynamics,2008,(5):13-15)
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9申重阳,李辉,付广裕.丽江7.0级地震重力前兆模式研究[J].地震学报,2003,25(2):163-171.(Shen Chongy-ang,Li Hui and Fu Guangyu.Study on a gravity precursor mode of the Lijiang earthquake[J].Acta Seismological Sini-ca,2003,16(2):175-184)
10申重阳.地壳形变与密度变化耦合运动探析[J].大地测量与地球动力学,2005,(3):7-12.(Shen Chongyang.Preliminary analysis of coupling movement between crustal deformation and density change[J].Journal of Geodesy and Geodynamics,2005,(3):7-12)
11申重阳,李辉.研究现今地壳运动和强震机理的一种方法[J].地球物理学进展,2007,22(1):49-56.(Shen Chongyang and Li Hui.A method of analyzing the present crustal movement and the mechanism of strong shocks[J].Progress in Geophysics,2007,22(1):49-56)
12李瑞浩,等.唐山地震前后区域重力场变化机制[J].地震学报,1997,19(4):399-407.(Li Ruihao,et al.The mechanism of regional gravity changes before and after the Tangshan earthquake[J].Acta Seismologica Sinica,1997,19(4):399-407)
13申重阳,等.重力场动态变化与汶川Ms8.0地震孕育过程[J].地球物理学报,2009,52(10):2547-2557.(Shen Chongyang,et al.Dynamic variations of gravity and the preparation process of the WenchuanMs8.0earthquake[J].Chinese J.Geophys,2009,52(10):2547-2557)
2尹光华,蒋靖祥,吴国栋.2008年3月21日于田7.4级地震的构造背景[J].干旱区地理,2008,31(4):543-549.(Yin Guanghua,Jiang Jingxiang and Wu Guodong.Tectonic background of theMs7.4earthquake at Yutian on March21,2008[J].Arid Land Geography,2008,31(4):543-549)
3李辉,等.中国大陆近期重力场动态变化图像[J].大地测量与地球动力学,2009,(3):1-10.(Li Hui,et al.Dy-namic gravity change of recent years in China continent[J].Journal of geodesy and geodynamics,2009,(3):1-10)
4马杏垣,宿俭,吴大宁.中国的活动块体运动与构造变形[A].现代地壳运动研究(3)-活动构造与减轻地质灾害[C].北京:地震出版社,1987.(Ma Xingyuan,Su Jian and Wu Daning.China’s active block and tectonic deforma-tion[A].present-day crustal movement study(3)-active structure and geologic disaster mitigation[C].Beijing:Seis-mological Press,1987)
5丁国瑜,卢演俦.对我国板内运动状况的初步探讨[J].科学通报,1986,31(18):1412-1415.(Ding Guoyu and Lu Yanchou.The Preliminary study on intraplate movement status of our country[J].Chinese Science Bulletin,1986,31(18):1412-1415)
6丁国瑜.我国大陆的新构造变形与板内现代运动[A].国际大陆岩石圈构造演化与动力学讨论会-第三届全国构造地质会议论文选集(II)[C].北京:科学出版社,1990.(Ding Guoyu.New tectonic deformation and present-day intra-plate movement of China continent[A].Symposia of International symposium on continental lithosphere tecton-ic evolvement and dynamics-the third national tectonic ge-ology symposium(Ⅱ)[C].Beijing:Science Press,1990)
7中国岩石圈动力学图集编委会.中国岩石圈动力学地图集[M].北京:中国地图出版社,1989.(China Lithosphere Dynamic Atlas Compilation Committee.China ithosphere dy-namic atlas[M].Beijing:SinoMaps Press,1989)
8应绍奋,等.中国大陆垂直向现代地壳运动基本特征[J].中国地震,1988,4(4):1-8.(Ying Shaofen,et al.Basic characteristics of recent vertical crustal movement of China mainland[J].Earthquake Research in China,1988,4(4):1-8)
9申重阳,李辉,付广裕.丽江7.0级地震重力前兆模式研究[J].地震学报,2003,25(2):163-171.(Shen Chongy-ang,Li Hui and Fu Guangyu.Study on a gravity precursor mode of the Lijiang earthquake[J].Acta Seismological Sini-ca,2003,16(2):175-184)
10申重阳.地壳形变与密度变化耦合运动探析[J].大地测量与地球动力学,2005,(3):7-12.(Shen Chongyang.Preliminary analysis of coupling movement between crustal deformation and density change[J].Journal of Geodesy and Geodynamics,2005,(3):7-12)
11申重阳,李辉.研究现今地壳运动和强震机理的一种方法[J].地球物理学进展,2007,22(1):49-56.(Shen Chongyang and Li Hui.A method of analyzing the present crustal movement and the mechanism of strong shocks[J].Progress in Geophysics,2007,22(1):49-56)
12李瑞浩,等.唐山地震前后区域重力场变化机制[J].地震学报,1997,19(4):399-407.(Li Ruihao,et al.The mechanism of regional gravity changes before and after the Tangshan earthquake[J].Acta Seismologica Sinica,1997,19(4):399-407)
13申重阳,等.重力场动态变化与汶川Ms8.0地震孕育过程[J].地球物理学报,2009,52(10):2547-2557.(Shen Chongyang,et al.Dynamic variations of gravity and the preparation process of the WenchuanMs8.0earthquake[J].Chinese J.Geophys,2009,52(10):2547-2557)
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