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地震 ›› 2008, Vol. 28 ›› Issue (1): 100-106.

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2005年11月26日江西九江-瑞昌MS5.7地震序列的破裂过程研究

陈学忠1, 吕坚2, 王慧敏3   

  1. 1.中国地震局地球物理研究所, 北京 100081;
    2.江西省地震局, 南昌 330039;
    3.中国地震台网中心, 北京 100043
  • 收稿日期:2007-09-05 修回日期:2007-10-15 出版日期:2008-01-31 发布日期:2021-10-29
  • 作者简介:陈学忠(1963-), 男, 重庆永川人, 研究员, 主要从事数字地震学、 地震预报方法等研究。

Investigation on rupture process of the Jiujiang- Ruichang earthquake sequence of November 26, 2005

CHEN Xue-zhong1, LU Jian2, WANG Hui-min3   

  1. 1. Institute of Geophysics, CEA, Beijing 100081;
    2. Earthquake Administration of Jiangxi Province, Nanchang 330039;
    3. China Earthquake Networks Center, CEA 100036, China
  • Received:2007-09-05 Revised:2007-10-15 Online:2008-01-31 Published:2021-10-29

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摘要： 利用江西南昌遥测台网和临时台网资料, 借助于主地震相对定位法, 对2005年11月26日江西九江-瑞昌MS5.7地震序列进行了重新定位, 分析了该序列的破裂过程。 这次地震的余震震中呈线性分布, 约沿北西37°, 与美国哈佛大学给出的主震震源机制解中的N35°W节面和北西向的洋鸡山-武山-通江岭断裂的走向基本一致, 震中位于该断裂的东南端。 这次地震破裂扩展过程主要发生在2005年11月30日19时前, 其后平稳。 主震发生在余震分布区的西北端部, 似乎表明本次地震为单侧破裂, 破裂向东南方向扩展。 震后4小时内震源深度由浅到深变化, 之后逐渐稳定在15 km左右。 破裂过程大致可分为两个阶段: 第1个阶段是从主震到2005年11月26日16时22分0.8秒, 破裂尺度为13.8 km, 历时约7.54小时, 平均破裂速度约为50.8 cm/s; 第2个阶段是从2005年11月29日11时35分21.7秒到2005年11月30日19时57分58秒, 破裂尺度为17.9 km, 历时约32.4小时, 平均破裂速度约为15.4 cm/s。 整个破裂过程扩展了31.7 km, 平均破裂速度约为22 cm/s, 前一阶段速度明显高于后一阶段, 破裂是减速的。

关键词: 九江地震, 相对定位, 破裂过程

Abstract: The Jiujiang-Ruichang earthquake sequence (MS5.7), occurred in Jiujiang, Jiangxi Province, on November 26, 2005 is relocated by the main shock location method using the data of arrival time of P, S and Pn waves recorded by Nanchang regional digital seismic station networks and temporary seismic stations, and the rupture process is analyzed. The epicenters of aftershocks of this sequence are distributed along a direction of N37°W. This consists with the N35°W node plane of focal mechanism of the mainshock determined from the seismic wave data by the Harvard university, also consists with the NW-striking Yangjishan-Wushan-Tongjiang fault, and the epicenter is located at the southeast end of the fault. The rupture extended before 19:00, 30, Nov 2005, and then remained relatively stable. The main shock located on the northwestern margin of the region where aftershocks distributed, it seems that this earthquake ruptures unilaterally towards the southeast. The focal depth of after shocks increases in four hours after the main shock, and then remains stable at a depth of about 15 km gradually. The process of rupture can be divided into the following two phases: Phase 1, from the main shock to 16:22:0.8, 26, Nov 2005 lasting for about 7.54 hours. The size of rupture zone is around 13.8 km.The mean velocity of rupture is approximately 50.8 cm/sec. Phase 2, from 11:35:21.7, 29, Nov 2005 to 19:57:58, 30, Nov 2005 lasting for about 32.4 hours. The size of rupture zone reaches to 17.9 km. The mean velocity of rupture is approximately 15.4 cm/sec. The rupture totally propagates for a distance of 31.7 km with a mean velocity of 22 cm/sec.The velocity of the former phase is obviously greater than that of the latter one, and the rupture is retardatory.

Key words: The Jiujiang-Ruichang earthquake, Main shock location method, Process of rupture

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