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本文基于宾川气枪地震信号发射台激发的地震波信号,利用线性叠加和时频域相位加权叠加方法提高信噪比,通过反褶积、插值拟合和波形互相关等方法,获得2021年漾濞M;6.4地震前后气枪震源初至波信号走时变化特征.结果表明两种叠加方法得到的走时变化趋势基本一致,在沿发震断裂带附近的3个台站观测到的初至波走时延迟为7.3~14.4 ms,在射线路径上平均波速降低了0.08%~0.12%,距离震中位置较远的台站走时延迟为2~6 ms.分析认为,观测到的走时变化主要是漾濞M;6.4地震引起强地面运动造成浅层介质疏松、同震破裂导致震源区地下介质裂隙增加和地下流体侵入等共同作用造成,相关研究成果有助于加深和促进对此次地震震源物理过程的认识和了解. 相似文献
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In order to further deepen the understanding of seismic wave propagation characteristics induced by the large volume airgun source, experimental data from multiple fixed excitation points in Fujian Province were used to obtain the equivalent single excitation high signal-to-noise ratio velocity and displacement records through linear stacking and simulation techniques. Then the peak displacements of different epicentral distances were used to calculate the equivalent magnitude of the airgun source excitation at different fixed excitation points so as to establish the attenuation relationship between equivalent magnitude,epicenter distance and velocity peak. Our results show that:① Within 270 km of epicentral distance,for the large-volume airgun's single shot,the peak velocity range is about 700-4 nm/s,and the peak displacement range is about 200. 0-0. 2 nm;② The equivalent magnitude of the P-wave from the airgun source with a total capacity of 8,000 in 3 is 0. 181-0. 760,and the equivalent magnitude of the S-wave is 0. 294-0. 832. By contrast,the equivalent magnitude of the P-wave from the airgun source with a total capacity of 12,000 in 3 is 0. 533-0. 896,and the equivalent magnitude of the S-wave is 0. 611-0. 946. The S-wave energy is greater than the P-wave energy, and the excitation efficiency varies greatly with different excitation environment;③ The peak velocity increases with the equivalent magnitude,and decreases with the epicentral distance. The vertical component of the P-wave peak velocity is the largest among those three components,while the S-wave has the smallest vertical component and similar horizontal components. Hence,our research can provide an important basis for the quantitative judgment of the seismic wave propagation distance using the airgun and the design of the observation system in deep exploration or monitoring with airgun. 相似文献
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大容量气枪震源长江定点激发信号检测 总被引:3,自引:2,他引:1
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。本文针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分析近场和远场信号的时频特性,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,最近的传播距离为180km,最远共有3个激发点传播达到260km,夜晚激发信号传播距离较远。 相似文献
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利用大容量气枪震源在陆上水库进行地震波激发试验,研究陆上水库环境下激发气枪震源所产生的地震波特征及传播距离. 试验结果表明,大容量气枪震源是具有丰富的10 Hz以下低频信号的低频震源,其激发的地震波具有传播距离远,穿透深度深的特点. 在185 km长的测线上均记录到了气枪信号,成功检测到Pg,Pc,P2,PmP和Pn等多组震相,并在此基础上对地下深地壳结构进行了一维速度结构正演,讨论了该区域壳幔过渡带的低速结构. 气枪震源还具有一般炸药震源不具有的特征,如长期定点重复激发和有效转换S波的优点,是陆上进行长炮检距深穿透地下结构研究的一种优良人工震源. 相似文献
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In this study, Qilian Mountain active source airgun signals recorded at 79 stations were obtained after stacking waveforms from July 2015 to December 2016. Based on analysis of the amplitude variation characteristics of the airgun signals, the following conclusions were drawn:along the NW-SE fault distribution direction of the Qilian Mountain area, the decrease in amplitude of airgun signals was relatively slow in relation to the epicentral distance, while the decrease in amplitude in the direction perpendicular to the fault was relatively fast. This difference may be related to the energy loss of seismic waves reflecting and scattering by the regional faults mainly distributed along the NW-SE direction, which are caused by tectonic compression of the Qinghai-Tibet and Alxa blocks. 相似文献
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利用固定台站分析长江激发气枪信号特征 总被引:1,自引:1,他引:0
“地学长江计划”安徽实验是以气枪震源为核心的大型主动源探测实验。通过在长江安徽段20个固定点定点激发气枪震源,结合109个固定台站、11条流动测线组成的观测网络,首次利用主动源实现了对长江流域安徽段约6万km2面积的三维地下结构探测。本文利用固定台站对长江激发气枪信号进行了分析,结果表明,长江中气枪信号激发效果良好,固定台记录中气枪信号可识别的最远距离达300km。对气枪信号绝对振幅的研究结果表明:① 50km处的气枪信号约为10nm量级,200km处的气枪信号小于1 nm;② 气枪信号强度的空间分布存在一定的方位各向异性,可能与长江的几何形状有关;③ 台站背景噪声对于提取气枪信号至关重要,高质量的固定台网为识别nm量级气枪信号提供了可能。 相似文献
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安徽气枪实验固定台层析成像初步结果 总被引:3,自引:2,他引:1
为探索气枪震源在探测区域性地壳结构中的应用, 2015年10月10~20日在长江马鞍山-安庆段开展气枪流动激发实验(安徽实验),在20个固定点定点激发2973炮,中间流动激发1872炮,由周边109个固定台、700个流动台(包括11条测线)进行接收。为获取郯庐断裂带南端较为精细的地壳速度结构,本文利用安徽气枪实验中采集到的固定台数据进行初至P波震相拾取,对20个气枪源、52个台站、335个震相进行体波层析成像,验证了利用气枪震源进行体波层析成像的可行性,并得到了P波速度结构的一些初步结果:①利用大容量气枪震源可进行三维体波层析成像;②15km深度的成像结果显示出大区域高低速异常区的清晰轮廓,即从研究区中心向外整体呈现出低-超低-低-高的分布特征,与地质构造背景相关,具有显著的横向不均匀性;③秦岭-大别造山带显示出高速异常,与其深部超高压变质岩相对应,而长江中下游地区整体呈现低速异常,与其特殊的成矿背景相对应。 相似文献