临震次声异常产生的机理研究
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摘要
为研究观测到的震前次声异常,提出了强地震发生前次声波异常信号产生的机理模型．该模型采用膨胀扩容孕震理论,将大气对流层与地质体作为一个动力学系统,采用瞬态有限元模拟方法计算分析了孕震末期地表变形及其产生的次声波和频率．结果表明,该模型的确能在空气中产生次声波,且次声波的主要频率是孕震体膨胀一收缩时间周期的倒数;孕震体收缩变形阶段产生的声压波幅远大于膨胀阶段．
A mechanism model was proposed to explain the infrasound abnormality observed just several days before a strong earthquake. The model includes a layered rock geo-structure, air media and their interaction. A transient dynamic finite element analysis was carried out to simulate the formation of the infrasound. The waveform and frequency of the simulated infrasound were analyzed. The results show that the proposed model is able to produce infrasound and its frequency which agree well with that from the observed. The frequency is inversely proportional to the expansion-contracting period of the earthquake source body. The fluctuating range of the air pressure during the contracting is greater than that during the expansion.
A mechanism model was proposed to explain the infrasound abnormality observed just several days before a strong earthquake. The model includes a layered rock geo-structure, air media and their interaction. A transient dynamic finite element analysis was carried out to simulate the formation of the infrasound. The waveform and frequency of the simulated infrasound were analyzed. The results show that the proposed model is able to produce infrasound and its frequency which agree well with that from the observed. The frequency is inversely proportional to the expansion-contracting period of the earthquake source body. The fluctuating range of the air pressure during the contracting is greater than that during the expansion.
引文
[1] LI Jun-zhi, BAI Zhi-qiang, CHEN Wei-sheng, et al. Strong earthquakes can be predicted: a multidisciplinary method for strong earthquake prediction[J]. Natural Hazards and Earth System Sciences,2003, 3: 703-712.
[2]夏雅琴,胡争杰,郑菲．震前次声波信号特征研究[J]．北京工业大学学报,2005,31(5):461-470．XIA Ya-qin, HU Zheng-jie, ZHENG Fei. Research of infrasound signal before earthquake[J]. Journal of Beijing University of Technology,2005,31(5): 461-470. (in Chinese)
[3]秦飞,郑菲．孕震过程中次声波产生的机理[J]．北京工业大学学报,2006,32(6):568-572．QIN Fei, ZHENG Fei. A mechanism model for infrasound emission during earthquake incubation[J]. Journal of Beijing Uni- versity of Technology,2006,32(6): 568-572. (in Chinese)
[4]李均之,沈壮．临震预报[J]．北京工业大学学报．1990,16(2):9-16．LI Jun-zhi, SHEN Zhuang. Imminent-term earthquake prediction[J]. Journal of Beijing Polytechnic University, 1990, 16(2): 9-16. (in Chinese)
[5] SCHOLZ C H, SYKES L R, AGGRAWALL Y R. Earthquake prediction: a physical basis[J]. Science,1973,181(4102): 803-809.
[6]陈颙．地壳岩石的力学性能[M]．北京:地震出版社,1988．
[7]宋治平,尹祥础,梅世蓉．地震孕育体源流变模型(二):应变场及其应用[J]．地震学报,2004．26(2):121-131．SONG Zhi-ping,YIN Xiang-chu,MEI Shi-rong.3-D rheologic model of earthquake preparation (2): strain field and its applications[J]. Acta Seismologica Sinica,2004,26(2): 121-131. (in Chinese)
[8]陈连旺,陆远忠,刘杰,等．1966年邢台地震引起的华北地区应力场动态演化过程的三维粘弹性模拟[J]．地震学报．2001,23(5):480-491．CHEN Lian-wang, LU Yuan-zhong, LIU Jie, et al. Three dimensional viscoelastic simulation on dynamic evolution of stress field in north China induced by the 1966 Xingtai earthquake[J]. Acta Seismologica Sinica,2001,23(5): 480-491. (in Chinese)
[9]马钦忠,钱家栋．层状介质中膨胀圆台体震源模型的应力场、应变场及位移场计算[J]．西北地震学报,1997,19(4): 31-39．MA Qin-zhong, QIAN Jia-dong. The calculation of stress and strain as well as displacement variations of the source model which is a dilatancy cone cylinder body in layered medium[J]. Northwestern Seismological Journal, 1997, 19(4): 31-39. (in Chinese)
[10]梅世蓉,梁北援,朱岳清．唐山地震前兆机制的数值模拟[J]．中国地震,1989,5(2):27-34．MEI Shi-rong, LIANG Bei-yuan, ZHU Yue-qing. Digital simulation on precursory mechanism of the 1976 Tangshan earth- quake[J]. Earthquake Research in China,1989,5(2): 27-34. (in Chinese)
[2]夏雅琴,胡争杰,郑菲．震前次声波信号特征研究[J]．北京工业大学学报,2005,31(5):461-470．XIA Ya-qin, HU Zheng-jie, ZHENG Fei. Research of infrasound signal before earthquake[J]. Journal of Beijing University of Technology,2005,31(5): 461-470. (in Chinese)
[3]秦飞,郑菲．孕震过程中次声波产生的机理[J]．北京工业大学学报,2006,32(6):568-572．QIN Fei, ZHENG Fei. A mechanism model for infrasound emission during earthquake incubation[J]. Journal of Beijing Uni- versity of Technology,2006,32(6): 568-572. (in Chinese)
[4]李均之,沈壮．临震预报[J]．北京工业大学学报．1990,16(2):9-16．LI Jun-zhi, SHEN Zhuang. Imminent-term earthquake prediction[J]. Journal of Beijing Polytechnic University, 1990, 16(2): 9-16. (in Chinese)
[5] SCHOLZ C H, SYKES L R, AGGRAWALL Y R. Earthquake prediction: a physical basis[J]. Science,1973,181(4102): 803-809.
[6]陈颙．地壳岩石的力学性能[M]．北京:地震出版社,1988．
[7]宋治平,尹祥础,梅世蓉．地震孕育体源流变模型(二):应变场及其应用[J]．地震学报,2004．26(2):121-131．SONG Zhi-ping,YIN Xiang-chu,MEI Shi-rong.3-D rheologic model of earthquake preparation (2): strain field and its applications[J]. Acta Seismologica Sinica,2004,26(2): 121-131. (in Chinese)
[8]陈连旺,陆远忠,刘杰,等．1966年邢台地震引起的华北地区应力场动态演化过程的三维粘弹性模拟[J]．地震学报．2001,23(5):480-491．CHEN Lian-wang, LU Yuan-zhong, LIU Jie, et al. Three dimensional viscoelastic simulation on dynamic evolution of stress field in north China induced by the 1966 Xingtai earthquake[J]. Acta Seismologica Sinica,2001,23(5): 480-491. (in Chinese)
[9]马钦忠,钱家栋．层状介质中膨胀圆台体震源模型的应力场、应变场及位移场计算[J]．西北地震学报,1997,19(4): 31-39．MA Qin-zhong, QIAN Jia-dong. The calculation of stress and strain as well as displacement variations of the source model which is a dilatancy cone cylinder body in layered medium[J]. Northwestern Seismological Journal, 1997, 19(4): 31-39. (in Chinese)
[10]梅世蓉,梁北援,朱岳清．唐山地震前兆机制的数值模拟[J]．中国地震,1989,5(2):27-34．MEI Shi-rong, LIANG Bei-yuan, ZHU Yue-qing. Digital simulation on precursory mechanism of the 1976 Tangshan earth- quake[J]. Earthquake Research in China,1989,5(2): 27-34. (in Chinese)
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