【摘要】 利用在北京昌平安装的次声三点阵,记录了2003年9月26日日本北海道地震的前兆次声波和震后次声波。实际记录的P-t曲线及波速波向图,经快速傅立叶变换得到其三维动态频谱。结果表明:①强震前2-7天能测到振幅很强、方向可测的地震前兆次声波。其频谱特点是:振幅由弱(10-15 Pa)逐渐加强到(50-80 Pa)或更大;先为短周期波(10-30 min),紧跟着长周期波(30-50 min),然后又出现更长的周期波,最后长短周期的波一起出现连成一片(2-62 min);②地震前兆次声波的产生和记录较容易,而当地次声波和震中次声波记录和识别比较困难;③若两地的三点阵波向相交,可预测震中位置。故地震前兆次声波的测量研究,有可能发展成为临震预报中一种有效的新方法更多还原

【Abstract】 A tripartite array in Changping, Beijing was arranged. The infrasonic signals (P-t curve, velocity and direction of wave) resulted from the earthquake on 26 September 2003 in Japan were observed. With fast Fourier transformation, the three-dimensional dynamic frequency spectra were obtained. The results of the spectrum analyses are as follows: 1. 2-7 days or so before occurrence of strong earthquake, the precursory infra-sound of earthquake with strong amplitude can often be observed. The spectrum characteristics are: the amplitudes of precursory infrasound vary from weak (10-15 Pa) to strong (50-80 Pa) or even stronger; their periods are in 10-30 minutes and 30-50 minutes respectively at first, and then become 2~62 minutes. Their waveforms are distinctly different from that of strong wind and thunderstorm. 2. The recording and recognizing of local and epicenter infrasound waves is not so easy as that of precursory infrasound. 3. If the directions of two tripartite arrays intersect, the location of epicenter will be obtained. So the measurement of the precursory infrasound could become a new and more effective method of the imminent earthquake prediction.更多还原