“311”东北日本M9.0大地震可预测性特征探索
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摘要
大地震不是任何地方都能发生的,大地震也不是任何时间都能发生的,大地震有其特定的时空结构。前期工作表明,条环交会、差异活动以及深震与"天外来客"事件等是制约发震时空窗口的主要因素。2011年3月11日发生在日本海沟俯冲带的M9.0大地震,其震前地震活动全面、清晰地展现出了其可预测性特征:(1)1925年开始出现的板间地震长期平静区;(2)2003年开始出现的位于平静区中部,起始于深震的海沟垂向地震活动条带;(3)2009年3月(海沟垂向地震活动条带形成后)开始出现的广义前震发震地方时的非随机显著聚集特征;(4)2011年3月9日(主震前2天)发生在平静区内的前震。主震发生在平静区边缘,海沟垂向地震活动条带与日本海沟板间地震带的交会处的地震活动差异性较大的地方,其断层面与海沟垂向地震活动条带内另外两个板间地震(2005-08-16地震和前震)的断层面共面。主震发生于广义前震发震地方时非随机聚集时段的中位时辰。日本大地震的可预测性特征逐一印证了我们的前期研究。
It is not anywhere and anytime that large earthquakes can occur.Large earthquakes occur in their special temporal and spatial windows.The intersection between earthquake strip and earthquake circularity,the difference in seismic activities,the earthquakes in great depth and the events outside the Earth are the main factors that control the temporal and spatial windows of large earthquake occurrences.An earthquake of magnitude of 9.0 occurred on 11 March 2011,off the Pacific Coast of the northeastern part of the Japanese main land(Tohoku Region).Before the earthquake of M9.0,in Japan Trench subduction zone,the seismic activities showed some characteristic predictability signs:(1) quiescence area of the interplate earthquake of Mj≥7.0,since 1925,(2) the strip of earthquake of Mj≥7.0 perpendicular to Japan Trench since 2003 which begins with a deep earthquake and locates in the middle of the quiescence area,(3) generalized foreshocks of Mj≥5.6 occur in a limited local time period,not random in nature,since March 2009,and(4) foreshock(2011-03-09 Mj7.3) occurs in the quiescence area.The main shock occurred at the place where in the margin of the quiescence area,at the intersection of an earthquake strip perpendicular to Japan Trench and the arc-shaped interpolate earthquake zone in Japan Trench subduction zone,in the area with a distinct spatial variability in seismic activities.The fault surface of the main shock looks to match coplanarly with the fault surfaces of another two interplate earthquakes of Mj≥7.0 in the earthquake strip perpendicular to Japan Trench.The main shock occurs in the middle of the local time period in which generalized foreshocks occur frequently.Predictability patterns of the Tohoku earthquake of M9.0 in 2011 are very similar as our previously discovered ones.
It is not anywhere and anytime that large earthquakes can occur.Large earthquakes occur in their special temporal and spatial windows.The intersection between earthquake strip and earthquake circularity,the difference in seismic activities,the earthquakes in great depth and the events outside the Earth are the main factors that control the temporal and spatial windows of large earthquake occurrences.An earthquake of magnitude of 9.0 occurred on 11 March 2011,off the Pacific Coast of the northeastern part of the Japanese main land(Tohoku Region).Before the earthquake of M9.0,in Japan Trench subduction zone,the seismic activities showed some characteristic predictability signs:(1) quiescence area of the interplate earthquake of Mj≥7.0,since 1925,(2) the strip of earthquake of Mj≥7.0 perpendicular to Japan Trench since 2003 which begins with a deep earthquake and locates in the middle of the quiescence area,(3) generalized foreshocks of Mj≥5.6 occur in a limited local time period,not random in nature,since March 2009,and(4) foreshock(2011-03-09 Mj7.3) occurs in the quiescence area.The main shock occurred at the place where in the margin of the quiescence area,at the intersection of an earthquake strip perpendicular to Japan Trench and the arc-shaped interpolate earthquake zone in Japan Trench subduction zone,in the area with a distinct spatial variability in seismic activities.The fault surface of the main shock looks to match coplanarly with the fault surfaces of another two interplate earthquakes of Mj≥7.0 in the earthquake strip perpendicular to Japan Trench.The main shock occurs in the middle of the local time period in which generalized foreshocks occur frequently.Predictability patterns of the Tohoku earthquake of M9.0 in 2011 are very similar as our previously discovered ones.
引文
[1]许绍燮.地震应可预测[M].北京:地震出版社,2011.Xu Shaoxie.Earthquake should be predicted[M].Beijing:Seismological Press,2011.
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[3]许绍燮.地震发震大尺度结构[J].科技导报,2010,28(23):26-33.Xu Shaoxie.Science&Technology Review,2010,28(23):26-33.
[4]赵树贤,许绍燮,吴平静,等.地震发生与日月运行之关联[J].科技导报,2011,29(13):18-23.Zhao Shuxian,Xu Shaoxie,Wu Pingjing,et al.Science&Technology Review,2011,29(13):18-23.
[5]Igarashi T,Matsuzawa T,Umino N,et al.Spatial distribution of focal mechanisms for interplate and intraplate earthquakes associated with the subducting Pacific plate beneath the northeastern Japan arc:A triple planed deep seismic zone[J].Journal of Geophysical Research,2001,106(B2):2177-2191.
[6]Uchida N,Matsuzawa T,Nakajima J,et al.Subduction of a wedge shaped Philippine Sea plate beneath Kanto,central Japan,estimated from converted waves and small repeating earthquakes[J].Journal of Geophysical Research,2010,115:B07309,doi:10.1029/2009JB006962.
[2]许绍燮.大地震时空窗口初探[J].科技导报,2012,30(4):18-25.Xu Shaoxie.Science&Technology Review,2012,30(4):18-25.
[3]许绍燮.地震发震大尺度结构[J].科技导报,2010,28(23):26-33.Xu Shaoxie.Science&Technology Review,2010,28(23):26-33.
[4]赵树贤,许绍燮,吴平静,等.地震发生与日月运行之关联[J].科技导报,2011,29(13):18-23.Zhao Shuxian,Xu Shaoxie,Wu Pingjing,et al.Science&Technology Review,2011,29(13):18-23.
[5]Igarashi T,Matsuzawa T,Umino N,et al.Spatial distribution of focal mechanisms for interplate and intraplate earthquakes associated with the subducting Pacific plate beneath the northeastern Japan arc:A triple planed deep seismic zone[J].Journal of Geophysical Research,2001,106(B2):2177-2191.
[6]Uchida N,Matsuzawa T,Nakajima J,et al.Subduction of a wedge shaped Philippine Sea plate beneath Kanto,central Japan,estimated from converted waves and small repeating earthquakes[J].Journal of Geophysical Research,2010,115:B07309,doi:10.1029/2009JB006962.
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