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顾国华, 王武星. GPS观测到的2004年印度洋9.3级等大地震前后地壳运动 [J]. 地震科学进展, 2023, (9): 437-448. doi: 10.19987/j.dzkxjz.2022-158" target="_blank" class="mainColor"> 10.19987/j.dzkxjz.2022-158.
引用本文: 顾国华, 王武星. GPS观测到的2004年印度洋9.3级等大地震前后地壳运动 [J]. 地震科学进展, 2023, (9): 437-448. doi: 10.19987/j.dzkxjz.2022-158" target="_blank" class="mainColor"> 10.19987/j.dzkxjz.2022-158.
Gu Guohua, Wang Wuxing. Crustal movements detected by GPS observations before and after the India Ocean earthquake of M9.3 in 2004 and other earthquakes [J]. Progress in Earthquake Sciences, 2023, (9): 437-448. doi: 10.19987/j.dzkxjz.2022-158" target="_blank" class="mainColor"> 10.19987/j.dzkxjz.2022-158.
Citation: Gu Guohua, Wang Wuxing. Crustal movements detected by GPS observations before and after the India Ocean earthquake of M9.3 in 2004 and other earthquakes [J]. Progress in Earthquake Sciences, 2023, (9): 437-448. doi: 10.19987/j.dzkxjz.2022-158" target="_blank" class="mainColor"> 10.19987/j.dzkxjz.2022-158.

GPS观测到的2004年印度洋9.3级等大地震前后地壳运动

Crustal movements detected by GPS observations before and after the India Ocean earthquake of M9.3 in 2004 and other earthquakes

  • 摘要: 2004—2012年印尼西部海域发生多次大地震,其中2004年印度洋9.3级巨震为21世纪以来全球最强。利用印尼及其邻近区域35个GPS连续观测站和中国大陆北京附近的GPS连续观测站BJFS站全球参考框架坐标时间序列,可得到以BJFS作为核心站的区域参考框架下这些观测站大地震震前位移积累、同震和震后位移,特别是震前水平位移积累和同震水平位移。该区大地震时空间隔密,且分布范围较大,观测站相互间与地震相关的地壳运动影响明显,地壳运动极为复杂。本文重点讨论了5次8级以上大地震前后地壳运动的特点、成因和相互影响。GPS观测结果显示,研究区域内7.5级以上地震的同震水平位移是震前水平位移积累的(弹性)回跳,震前水平位移积累是前兆。9.3级与2005年8.7级地震震级与时空相近,有重合与不重合的前兆形变区,是前者触发后者的主要条件;而9.3级与8.7级震后强烈地壳水平运动与2012年8.6级和8.2级地震的发生直接有关;2007年8.4级地震的发生与9.3级和8.7级地震无明显关系,但其震后水平位移影响了赤道南8.6级和8.2级地震的同震水平位移。尽管所采用的GPS连续观测站数量少、密度低,但仍为研究地震预测中多次地震前后地壳运动的复杂性提供了有意义的震例。研究表明,印尼西部地区是全球最有意义的地震预测探索区之一。

     

    Abstract: From 2004 to 2012, multiple strong earthquakes occurred in the western offshore of Indonesia and among them the Indian Ocean earthquake of M9.3 in 2004 has been the greatest in this century in the world. Based on the time series of coordinates at 35 stations of continuous GPS observations in Indonesia and its neighborhood in the global reference frame, the accumulated preseismic, coseismic and post seismic displacements, particularly the accumulated preseismic horizontal displacements and the coseismic horizontal displacements of these earthquakes in the regional reference frame with the core station at BJFS near Beijing on China mainland, are obtained. The crustal movements in the region has been quite complicated as shown by significant mutual influences in the crustal movements that were related at the GPS observation stations because of strong earthquakes of short time intervals and short spacing, scattering over a large area. The features, causes and mutual influences of the preseismic, coseismic and postseismic crustal movements of 5 earthquakes of magnitudes over M8.0 are discussed. Results of GPS observations show that the coseismic horizontal displacements of earthquakes of magnitudes larger than M7.5 were (elastic) rebound of the accumulated preseismic horizontal displacements, which were precursory to the earthquakes. The M9.3 in 2004 and M8.7 in 2005 were close in magnitudes. Occurrence time and spacing and the areas of anomalous crustal deformations in the preparation of both events were both overlapping and non overlapping, which was the prerequisite for the triggering of the latter by the former event. The intensive post seismic horizontal crustal movements of the M9.3 and M8.7 earthquakes significantly contributed to the occurrence of the M8.6 and M8.2 earthquakes in 2012. Though the occurrence of the M8.4 earthquake in 2007 was independent of the M9.3 and M8.7 earthquakes, the postseismic horizontal crustal movements of the M8.4 influenced the coseismic horizontal displacements of the M8.6 and M8.2 earthquakes, south to the equator. Though stations of continuous GPS observations used in this study is small in number and low in density, they have accumulated valuable earthquake cases of complicated crustal deformations before and after multiple strong earthquakes with GPS observations for the benefit of exploring earthquake predictions. The study shows that the western part of Indonesia is one of the most valuable areas for the exploration of earthquake predictions in the world.

     

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