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中强地震余震序列地震目录编目是否完备、震源参数是否准确,直接影响余震序列特征分析、震后趋势快速判断和强余震预测等研究结果的科学性和可靠性.2013年7月22日甘肃岷县-漳县MS6.6地震余震序列目录中存在较多单台记录地震事件,地震观测报告仅给出其震级,而未给出震中位置.由于余震波形间的相互交叠干扰,使得余震最大振幅的测量误差较大,造成地震观测报告给出的单台事件震级误差较大.精确估计单台记录地震事件的震中和震级,能够补充完善现有地震目录,提高地震目录的完备性.本文对单台记录地震事件震中和震级的估计不仅限于单个台站,而是通过分析区域台网中多个台站的波形记录实现.首先以余震序列中震级较大、波形记录信噪比较高的地震波形作为模板,使用波形互相关震相检测技术,检测单台记录的地震事件在多个台站的震相到时.如果能在4个以上台站检测到震相,则利用测震台网常用的HYPOSAT方法估计其震中位置,并利用多个台站记录波形与模板地震的振幅比估计其震级.之后计算主震发生后不同时间的最小完备性震级,并通过线性拟合得到最小完备性震级随时间变化的表达式,以分析此地震余震序列的目录完备性.经过计算共得到253个单台记录地震事件的震级和其中177个事件的震中位置,其震中空间分布范围与余震序列中其它地震分布范围基本一致.震级复测以及与人工拾取震相到时误差对比表明,该方法所得震相检测和震级估计结果具有较好的可靠性.主震及最大余震发生后的短时间内,有较多数量单台事件的目录所给出的震级偏低,分析认为可能受主震与较大余震后续震相以及余震间相互干扰所致.主震发生0.02—0.3天内,其余震序列最小完备性震级随时间的对数呈线性下降,在0.3天后最小完备性震级稳定在ML1.1左右.
Whether the earthquake catalog cataloging of the medium-strong earthquake aftershock sequence is complete or not and whether the source parameters are accurate will directly affect the scientific analysis and reliability of aftershock sequence feature analysis, rapid judgment of post-earthquake trend and strong aftershock prediction, etc. July 22, 2013 Min Gansu There are many single event records in the aftershock sequence list of MS6.6 earthquake in County-Zhang County, and the earthquake observation report only gives the magnitude of the earthquake without giving the location of the epicenter.As a result of the overlapping interference of aftershock waveforms, the aftershock is made the largest The error of the amplitude measurement is relatively large, resulting in a large magnitude error in the single event given by the seismic observation report. Accurately estimating the epicenter and magnitude of a single earthquake event can supplement and perfect the existing earthquake catalog and improve the completeness of the earthquake catalog. The estimation of the epicenter and magnitude of a single earthquake event is not limited to a single station but is made by analyzing the waveform records of multiple stations in the regional network.Firstly, based on the larger magnitude of aftershocks and the higher signal-to-noise ratio Of the seismic waveforms as a template, the use of waveform cross-correlation phase detection technology to detect a single record of seismic events in the seismic phase of multiple stations to the time if When more than four stations detected the phase, the HYPOSAT method commonly used by the seismometer network was used to estimate the epicenter position, and the magnitudes of the recorded waveforms and the template earthquakes of multiple stations were used to estimate the magnitude of the epicenters. Then, The minimum completeness magnitude at different time and obtain the expression of minimum completeness magnitude change with time by linear fitting to analyze the catalog completeness of this aftershock sequence.A total of 253 records of earthquake magnitude and Among them, the epicenter position of 177 events is basically the same as the distribution range of other earthquakes in the aftershock sequence.The comparison of the magnitudes of the earthquakes and those obtained by the manual pick-up phase shows that the results of seismic phase detection and magnitude estimation obtained by this method have Better reliability.After the main shock and the largest aftershock shortly after the occurrence of a large number of single event directory given the magnitude of the low, the analysis may be affected by the main shock and the larger aftershock aftershocks and aftershocks Between the main shock occurred within 0.02-0.3 days, the minimum completeness of the aftershock sequence with the logarithm of linearity decreased linearly, after 0.3 days minimum complete Sex magnitude stable at about ML1.1.