摘要
研究了一种在大地震前出现的异常次声波,揭示其与地震发生的空间、时间、强度的对应关系.利用CASI-ICM-2011型次声测量传感器在一系列Ms6.0级以上大地震发生前2周以内检测到的一种频率范围0.001 Hz至0.01 Hz的次声波,其特征有:幅值范围50 Pa至200 Pa,持续时间0.5 h至4 h,传播速度10 m/s至30 m/s,震级越高信号越强.通过建立广域次声传感器网络,成功定位了芦山地震前4天出现的异常次声波,以及巴基斯担地震前12天出现的异常次声波.通过对8年时间连续监测数据的分析,研究了这类次声波的出现规律.同时,对其产生机理提出了大地起伏激发次声波的假设,进行了理论论证,并用智利地震测量信号和玉树地震测量信号证明S波可以激发出本地同振的次声波.文中所列举的数个震前异常次声信号的观测结果对于地震预测的信息获取具有参考价值.
Study on the precursor infrasound waves emitted before the occurrence of strong earthquakes has been performed, so as to discover the relationship among position, arriving time, intensity of the infrasound wave and earthquakes. With the special kind of infrasound microphone CASI-ICM-2011, a kind of infrasound waves with frequencies from 0.001 Hz to 0.01 Hz, peak sound pressure level from 50 Pa to 200 Pa, continuous time period from half hour to 4 hours, and propagation speed from 10 m/s to 30 m/s, arising no more than two weeks, was received before a series of earthquakes over Ms6.0 occur. Amplitude of the signal is higher when the earthquake is stronger. In the far field the sensor network was spread in north-east China with automatic data uploading to a central server computer in Beijing. Precursor infrasound waves emitted 4 days before Ms7.0 Lu-san earthquake have been positioned perfectly as a sound cloud map, also the infrasound wave emitted 12 days before Ms7.7 Pakistan earthquake has been positioned. A long-time continuous signal over 8 years has been analysed without a bit gap, showing several effective signals accompanying earthquakes. Law of the infrasound generation has been discussed with a suggestion for the mechanism that the infrasound could be radiated by a large scale surface vibration near one million square kilometers in earthquake developing. Two demonstrative signals received after Ms8.8 Chile earthquake and Yu-shu earthquake were provided to prove this suggestion. The detected signal shows that the infrasound wave arrives accompanying S wave at the same time. One model is provided as a piston sound source to simulate very low frequency infrasound radiated by large surface vibration. All the presented signals in this paper should be useful for precursor information obtained for close earthquake prediction.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第13期216-229,共14页
Acta Physica Sinica
基金
国家自然科学基金(批准号:11174320
11304352)资助的课题~~
关键词
地震前
异常次声波
次声观测
before earthquake
precursor infrasound
infrasound observation
