地震研究

利用格尔木基准地震台重力观测资料,检测到2011年3月11日日本东海岸9.0级特大地震激发 ₀S₀～₀S₄₀之间的球型自由振荡,其中有 ₀S₀、 ₀S₁₃、 ₀S₂₂、 ₀S₂₆、 ₀S₃₀共5个振型的

By use of the gravity digital observation data recorded at Golmud Reference Seismological Station,we detect the spherical free oscillation between the mode of ₀S₀ and ₀S₄₀ stimulated by the M9.0 earthquake occurred on March 11,2011 in Japan.The difference between the theoretical and the observed frequency values of the mode of ₀S₀、 ₀S₁₃、 ₀S₂₂、 ₀S₂₆、 ₀S₃₀ is almost zero.Meanwhile,we find that the mode of ₀S₂ and ₀S₃ have the phenomenon of spectra line splitting.But it is difficult to identify the mode of ₀S₃₂ and ₀S₃₇,because they are drowned in the noises.The whole mean deviation is about 0.10%,which shows that there is a good agreement between observed and theoretical frequency values.The results not only suggest the validity of the theory of Preliminary Reference Earth Model,but also show the excellent of gravity data recorded at Golmud Reference Seismological Station,so it maybe helpful to understand the structure in deep earth.

引言
1 格尔木重力仪对日本大地震的记录
2 数据选取及计算方法
3 计算结果
4 结论与讨论

图1 格尔木基准地震台重力仪对日本9.0级地震的分钟值记录<br/>Fig.1 Minute value records of the Japan M 9.0 earthquake recorded by the gravimeter at Golmud station

图1 格尔木基准地震台重力仪对日本9.0级地震的分钟值记录
Fig.1 Minute value records of the Japan M 9.0 earthquake recorded by the gravimeter at Golmud station

图2 不同频段重力记录功率谱密度估计曲线<br/>(a)0.28～1.80 mHz;(b)1.80～2.90 mHz; <br/>(c)2.90～3.85 mHz;(d)3.85～4.75 mHz<br/>Fig.2 Estimation curve of power spectrum density of the gravity records in different frequency range (a)0.28～1.80 mHz,(b)1.80～2.90 mHz,(c)2.90～3.85 mHz,(d)3.85～4.75 mHz

图2 不同频段重力记录功率谱密度估计曲线
(a)0.28～1.80 mHz;(b)1.80～2.90 mHz;
(c)2.90～3.85 mHz;(d)3.85～4.75 mHz
Fig.2 Estimation curve of power spectrum density of the gravity records in different frequency range (a)0.28～1.80 mHz,(b)1.80～2.90 mHz,(c)2.90～3.85 mHz,(d)3.85～4.75 mHz

表1 格尔木基准台重力仪球型振荡观测值、PREM 模型理论值及其偏差<br/>Tab.1 Observation value of the spheroidal oscillations recorded by gravimeter at Golmud standard station,the theoretical values of the PREM model and the differences between them

表1 格尔木基准台重力仪球型振荡观测值、PREM 模型理论值及其偏差
Tab.1 Observation value of the spheroidal oscillations recorded by gravimeter at Golmud standard station,the theoretical values of the PREM model and the differences between them

图3 震前重力记录波形及其功率谱密度估计曲线<br/>Fig.3 Waveform records of gravity and curve of power spectrum density estimation before the earthquake

图3 震前重力记录波形及其功率谱密度估计曲线
Fig.3 Waveform records of gravity and curve of power spectrum density estimation before the earthquake

图4 0S2振型(a)和 0S3振型(b)谱线分裂<br/>Fig.4 Spectra line splitting of mode 0S2(a) and mode 0S3(b)

图4 0S2振型(a)和 0S3振型(b)谱线分裂
Fig.4 Spectra line splitting of mode 0S2(a) and mode 0S3(b)

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备注

引言

1 格尔木重力仪对日本大地震的记录

2 数据选取及计算方法

3 计算结果

4 结论与讨论

期刊信息