摘要
利用海上大容量气枪作为震源,陆上固定台网和流动台站作为接收台阵的海陆地震联测试验在南海北部已开展多次,其中流动台站的布设一直是野外试验中至关重要的工作之一。作者以2011年海南岛海陆地震联测试验为基础,对野外流动台站的布设过程及注意事项进行了分析总结;从同一震源不同台基记录信号的差异性、不同震源同一台基记录信号的变化特征以及相近接收距离不同台基记录的信号特征等方面对以下3个不同类型台基上流动台站接收到的气枪信号进行了对比分析,发现接收到的气枪信号与台基的稳定性、环境噪音的大小存在紧密关系。在相近接收距离下,当布设台基为山脚成片的基性岩石时,流动台站接收到的信号信噪比很高,且波形持续时间较短,能量较为集中;当布设台基为河边冲积的岩石时,流动台站接收到的信号信噪比较差,且波形持续时间较长,能量较为分散,导致信号的到时难以分辨;而当布设台基为山顶半悬浮大块岩石时,流动台接收到的信号的信噪比最差。从处理的地震剖面可知,台基为成片出露的基性岩石时,震相数据最为清晰,拾取也更准确。
Onshore-offshore seismic experiment uses air-gun arrays as seismic sources,permanent and portable land stations and ocean bottom seismometers to form a signal record array.Such experiment has been carried out many times in the northern South China Sea,and layout of portable stations was always a key for the success in such a field experiment.This paper is based on the onshore-offshore seismic experiment in Hainan island during 2011.It summarizes the processes and matters that need attention during deploying portable stations,and analyzes air-gun signals received by portable stations on three different types of basements.We find that the received air-gun signals were closely related to the stability of the basement and the ambient noise.When using exposed abundant basic rock as the basement,portable stations acquired high signal-to-noise ratio（SNR）,and long duration of the waveform and more concentrated energy.When the basement was large semi-floating rockmass on a mountaintop,the portable stations received general SNR,and long duration of waveform.When the basement was rocks exposed in the sedimentary layer,the signal received by portable station performed lower SNR,longer duration of waveform,and decentralized energy;even the arrival time was hard to identify.From the processed profiles,we conclude thatclearly seismic phase and more accurate arrival time were easily acquired when exposed abundant basic rock was used as the basement.
出处
《热带海洋学报》
CAS
CSCD
北大核心
2012年第3期48-57,共10页
Journal of Tropical Oceanography
基金
国家自然科学基金项目(41006028,U0933006)
广东省自然科学基金资助项目(10451030101004522)
国家海洋局海底科学重点实验室基金(KLSG0904)
关键词
南海北部
海陆地震联测
流动台
信噪比
气枪信号
northern South China Sea
onshore-offshore seismic experiment
portable seismic station
signal-to-noise ratio
air-gun signal
