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ISSN 2096-7780 CN 10-1665/P

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.

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

  • 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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