海陆地震联测：相邻地震台站的信号及震相特征对比

Onshore-offshore seismic experiment: signal characteristics and seismic phases re-ceived by two adjacent seismic stations

2004年作者在香港外海域进行了一次海陆地震联测实验,文章利用此次实验中的两个相邻固定台站珠海台和澳门台所记录的气枪信号数据,从波形、波谱特性和震相等方面分析了相邻地震台站对气枪信号的响应特征。结果显示,来自不同距离处的地震波波形和波谱特征在同一台站上变化不大,但在不同台站上的响应有所差别,珠海台受背景噪声影响更为强烈,其信号波形扰动大,具有较多高频成分,优势频率响应比较尖锐,而澳门台响应则比较平缓。对研究区下方速度结构进行了二维结构模拟,分析了台站附近速度结构对地震波到时的影响。珠海台PmP震相走时相对滞后,由于深圳断裂带穿过两台站之间,其引起的花岗岩基底破碎或上地壳厚度的差异都可能导致珠海台基底地震波速度的降低,这可能也是引起两台站对相同震源信号具有不同波形及波谱响应的因素之一。

Based on the 2004 data recorded by two permanent seismic stations in Zhuhai and Macao that are adjacent to each other,we studied the characteristics of the seismic wave produced by the air-gun in the onshore-offshore deep seismic ex-periment near Hong Kong.We carried out comparative study on the waveform,spectrum character,and the travel time of dif-ferent seismic phases.The results show that characteristics of the seismic waveform that came from different distances were similar at a single station but had some variation between the two stations.The noise had a stronger influence on the signal received by the Zhuhai station,which resulted in serious disturbance and more high-frequency components on the signal wave-form.The frequency response had a relatively sharp edge at the Zhuhai station but more moderate at the Macao station.We also obtained the laterally homogeneous 2-D models analyzed how different crust structures influence the time that the seismic wave travels.The PmP phase at the Zhuhai station traveled more slowly than that at the Macao station.We suggest that the fragmenta-tion of the granite basis and different thickness of the upper crust caused by the Shenzhen Fault may lead to the slower crustal seismic velocity,which is also considered to have caused the different waveform and frequency responses at the two stations.