大容量气枪震源长江定点激发信号检测

Signal detection of large volume air­gun source excitation in the fixed field of the Yangtse River

摘要:

地学长江计划安徽段实验是大容量气枪震源在长江的首次激发。本文对布设在气枪固定激发点附近的流动台和周边固定台接收到的气枪信号进行线性叠加，以分析近场、远场信号的时频特性，并利用叠加结果检测气枪信号的传播特性，分析不同环境因素对信号传播距离的影响。结果表明：①近岸首台可以接收到清晰的压力脉冲、气泡脉冲的体波和面波信号；②气枪信号主频为5Hz左右，随着震中距的增加，压力脉冲信号衰减很快，信号主频频带变窄；③对信号传播距离进行初步检测发现，最近的传播距离为180km，最远共有3个激发点传播达到260km，夜晚激发时信号传播距离较远。

Abstract:

It is the first time for large volume air-gun excited in the Yangtse River，so it is necessary to study the time-frequency characteristic based on the linear stacked seismic data from records from temporary stations near the fixed fields and seismic stations. Air-gun signal propagation distances were detected using the stacked seismic data to analyze the environmental impact on signal propagation distance. The results showed that：(1)the air-gun signal produced by bubble pulses，pressure pulses and surface wave can be received by the temporary station near by fixed field；(2)the dominant frequency of bubble at 5Hz or so can be received by both near-field stations and far-field stations，pressure pulses rapidly weakens and the dominant frequency bands get narrower as epicentral distance increases；(3)the longest spread distance of signal is 260km，the nearest is 180km，and the signal can travel further in evening.