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选取2004年12月26日印尼苏门答腊MW9.0地震的余震分布空间范围为研究区域,该区域位于缅甸小板块中部,纬度范围为2°N～15°N.根据USGS地震目录,研究了2004年印尼苏门答腊MW9.0地震前地震频次的时空变化,并分析了地震活动与地球自转的关系.结果显示:1)在余震区域范围内,地震频次自2000年开始出现了明显的上升趋势变化,反映了地震活动的增强过程,临近地震发生前,地震频次有一定幅度的回落;2)通过地震频次空间扫描,发现震前在震中附近区域地震活动增强显著;3)在1990～2004年的15年中,单位时间内发生的地震数在地球自转季节性变化减速时段与加速时段之比值rda在震前出现明显的上升过程:1998年～2002年rda缓慢上升,2002年底rda快速上升达最高值,之后,rda呈现下降趋势,直至苏门答腊MW9.0地震发生;4)2000年1月～2004年11月间,在纬度1°N～7°N的空间范围内的震中附近地区,5.5级以上地震都发生在地球自转季节性变化减速时段内;5)地震活动累积年频次相对于其长期平均值的变化量ΔN与地球自转“十年起伏”变化关系表现为地球自转减速时ΔN上升,地震活动增强,加速时ΔN下降,地震活动减弱.这些现象并非偶然,可能预示着地球自转减速与苏门答腊MW9.0地震之间存在着某种联系,这些结果对地震孕育过程的认识和地震预测研究具有一定的价值.
The spatial distribution of aftershocks of the Mw9.0 earthquake in Sumatra, Indonesia, on December 26, 2004, is selected as the study area, which is located in the middle of Myanmar platelets and latitude ranges from 2 ° N to 15 ° N. According to the USGS earthquake catalog, The spatial and temporal variations of the earthquakes frequency before the MW9.0 earthquake in Sumatra, Indonesia, and the relationship between the seismic activity and the Earth’s rotation are analyzed.The results show that: 1) In the area of aftershocks, the frequency of earthquakes has obviously changed upward since 2000, reflecting The frequency of earthquakes eased to a certain extent before the earthquake; 2) the seismic activity in the area around the epicenter before the earthquake was found to be significantly enhanced by the seismic frequency-space scanning; 3) In the 15 years from 1990 to 2004 , The number of earthquakes occurred per unit time in the earth’s rotation seasonal change deceleration period and acceleration period ratio rda before the earthquake showed a clear rise: rda slowly increased from 1998 to 2002, rda at the end of 2002 rose rapidly to the highest value, Later, the rda showed a downward trend until the Sumatra MW9.0 earthquake occurred. 4) From January 2000 to November 2004, in the vicinity of the epicenter within the spatial latitude of 1 ° N to 7 ° N, Earthquakes of magnitude 5 and above occur during the period of seasonal variation of Earth’s rotation; 5) The variation of accumulated annual frequency of earthquakes relative to its long-term average, ΔN, is related to the Earth’s rotation and the “decade fluctuation” When ΔN rises, the seismic activity increases, ΔN decreases and the seismic activity weakens during the acceleration. These phenomena are not accidental, which may indicate that there is a connection between the deceleration of the Earth’s rotation and the Sumatra MW9.0 earthquake. The results of the understanding of the earthquake breeding process And earthquake prediction research has some value.