北京一次小震级地震前异常声-重力波产生机理的研究
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摘要
观测到北京一次小震级地震(ML=3.0)前的异常声-重力波,并同时记录到异常地表倾斜信号。二者相关系数比较高,在接近震中的地区相关系数达到最大值0.5,相关系数随着远离震中的距离增大而减小。经过研究表明,异常声-重力波的产生与震前的地表缓慢活动引发的山体缓慢晃动导致的气流风速波动变化有关。基于350 m高的气象铁塔观测的风速数据,对两层大气模型传播的声-重力波进行了数值计算,得到的相对山体非平稳气流引起的声-重力波与观测信号在特征周期、幅度和速度三个参数上近似。以地表倾斜为例的模型与观测数据的一致性表明该震前声-重力波与地震存在关联性。
Observation results of abnormal acoustic-gravity waves before a Beijing earthquake(ML = 3.0) are presented.During this period,abnormalities of earth surface tilt variations were also recorded.The cross-correlations between the both values are high,which reach maximal values of 0.5 in the area close to the epicenter.The correlations decrease with increasing distances from the epicenter.It was proposed that generation of the anomalous waves may be associated with the pressure and wind perturbations in the air flow caused by slowly shaking mountains during slow suface motion preceding the earthquake in Beijing.Based on the wind velocity data taken from a 350 m meteorological tower in Beijing,the propagation of ducted acoustic-gravity waves in a two-layer model of the atmosphere was numerically simulated.It is shown that characteristic periods,amplitudes and velocities of the simulated phases which were assumed from non-stationary air flow relative to mountains are approximate to the observed phases.A consistency between the simulated results and observation data indicates that a slow surface motion may be a possible source of the anomalous acoustic-gravity waves observed prior to the earthquake.
Observation results of abnormal acoustic-gravity waves before a Beijing earthquake(ML = 3.0) are presented.During this period,abnormalities of earth surface tilt variations were also recorded.The cross-correlations between the both values are high,which reach maximal values of 0.5 in the area close to the epicenter.The correlations decrease with increasing distances from the epicenter.It was proposed that generation of the anomalous waves may be associated with the pressure and wind perturbations in the air flow caused by slowly shaking mountains during slow suface motion preceding the earthquake in Beijing.Based on the wind velocity data taken from a 350 m meteorological tower in Beijing,the propagation of ducted acoustic-gravity waves in a two-layer model of the atmosphere was numerically simulated.It is shown that characteristic periods,amplitudes and velocities of the simulated phases which were assumed from non-stationary air flow relative to mountains are approximate to the observed phases.A consistency between the simulated results and observation data indicates that a slow surface motion may be a possible source of the anomalous acoustic-gravity waves observed prior to the earthquake.
引文
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9林琳,杨亦春大气中的一种低频次声波观测研究.声学学报,2010;35(2):200-207
10夏雅琴,崔晓艳,李均之等震前次声波异常信号的研究.北京工业大学学报,2011;37(3):463-469
11 Xia Y Q,Liu J Y,Cui X Y et al.Abnormal infrasound signals before 92 M≥7.0 worldwide earthquakes during2002-2008.Journal of Asian Earth Sciences,2011;41:434-441
12 Liu C Y,Liu J Y,Chen W S et al.An integrated study of anomalies observed before four major earthquakes:2004 Sumatra M9.3,2006 Pingtung M7.0.2007 Chuetsu Oki M6.8,and 2008 Wenchuan M8.0.Journal of Asian Earth Sciences,2011;41:401-409
13秦飞,郑菲,李俊之等.孕震过程中次声波的产生机理.北京工业大学学报,2006;32(6):568-572
14杨训仁.大气声学(第二版).北京:科学出版社,2007:19
15 Evers L G.The inaudible symphony:on the detection and source identification of atmospheric infrasound.Ph.D thesis,Delft university of technology,2008:25
16 Gossard E E,Hooke W H.Waves in the atmosphere.New York:Elsevier Scientific Publishing Company,1975:215
17 Chunchuzov I P.On a possible generation mechanism for nonstationary mountain waves in the atmosphere.Journal of the Atmospheric Sciences,1994;51(15):2196-2206
2 Shinagawa H,Iyemori T,Saito S,Maruyama T.A numerical simulation of ionospheric and atmospheric variations associated with the Sumatra earthquake on December 26,2004.Earth Planets Space,2007;59:1015-1026
3 Mikumo T,Shibutani T,Le Pichon A et al.Low-frequency acoustic-gravity waves from coseismic vertical deformation associated with the 2004 Sumatra-Andaman earthquake(M_w=9.2).J.Geophys.Res.,2008;113:B12402
4 Mutschlecner J P,Whitaker R W.Infrasound from earthquakes.J.Geophys.Res.,2005;110:D0108
5 Le Pichon A,Blanc E,Hauchecorne A.Infrasound monitoring for atmospheric studies.New York:Springer,2010:7
6陈双贵,杨斐,陈继锋等.长周期形变波特征分析.地震研究,2011,34(3):308-312
7张晁军,石耀霖,马丽.慢地震研究中的一些问题.中国科学院研究生院学报,2005;22(3):258-269
8吕君,郭泉,冯浩楠等.北京地震前的异常次声波.地球物理学报,2012;55(10):3379-3385
9林琳,杨亦春大气中的一种低频次声波观测研究.声学学报,2010;35(2):200-207
10夏雅琴,崔晓艳,李均之等震前次声波异常信号的研究.北京工业大学学报,2011;37(3):463-469
11 Xia Y Q,Liu J Y,Cui X Y et al.Abnormal infrasound signals before 92 M≥7.0 worldwide earthquakes during2002-2008.Journal of Asian Earth Sciences,2011;41:434-441
12 Liu C Y,Liu J Y,Chen W S et al.An integrated study of anomalies observed before four major earthquakes:2004 Sumatra M9.3,2006 Pingtung M7.0.2007 Chuetsu Oki M6.8,and 2008 Wenchuan M8.0.Journal of Asian Earth Sciences,2011;41:401-409
13秦飞,郑菲,李俊之等.孕震过程中次声波的产生机理.北京工业大学学报,2006;32(6):568-572
14杨训仁.大气声学(第二版).北京:科学出版社,2007:19
15 Evers L G.The inaudible symphony:on the detection and source identification of atmospheric infrasound.Ph.D thesis,Delft university of technology,2008:25
16 Gossard E E,Hooke W H.Waves in the atmosphere.New York:Elsevier Scientific Publishing Company,1975:215
17 Chunchuzov I P.On a possible generation mechanism for nonstationary mountain waves in the atmosphere.Journal of the Atmospheric Sciences,1994;51(15):2196-2206
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