| 2013年甘肃岷县-漳县MS6.6地震余震 序列目录完备性研究 基于对单台记录地震事件震中与震级的估计 |
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| 引用本文： | 谭毅培,陈继锋,曹井泉,邓莉,东得淼.2013年甘肃岷县-漳县MS6.6地震余震 序列目录完备性研究 基于对单台记录地震事件震中与震级的估计[J].地震学报,2015,37(5):806-819. |
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| 作者姓名： | 谭毅培 陈继锋 曹井泉 邓莉 东得淼 |
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| 作者单位： | 1.天津 300201 天津市地震局 |
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| 基金项目： | 地震科技星火计划项目XH15004Y地震行业科研专项201208009 |
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| 摘 要： | 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.
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| 关 键 词： | 目录完备性 单台地震事件 震相检测 波形互相关 2013年岷县-漳县MS6.6地震 |
| 收稿时间： | 2014-11-25 |
CataIogue compIeteness anaIysis on aftershock sequence of the 2013 Minxian-Zhangxian,Gansu,MS6.6 earthquake based on Iocation and magnitude estimation of singIe-station earthquake events |
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| Institution: | 1.Earthquake Administration of Tianjin Municipality, Tianjin 300201, China2.Earthquake Administration of Gansu Province, Lanzhou 730000, China |
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| Abstract: | Catalogue of aftershock sequences of moderate-strong earthquakes provide important basic data for the study on aftershock sequence characteristics analysis，postseismic trend quick judgement and strong aftershock prediction. The completeness of catalogue and accuracy of source parameters have direct influence on the reliability of research results. There are a lot of single-station earthquake events in the catalogue of the Minxian-Zhangxian，Gansu，MS6.6 earthquake on July 22，2013，whose epicenter locations are not given in earthquake observation report. According to the waveforms mutual interference of the aftershocks，magnitude are not reliable enough due to the lager error of amplitude measurement. Accurate estimation of location and magnitude of single-station earthquake events can supplement and improve the existent catalogue so as to enhance the completeness of the catalogue. In this paper we estimate the location and magnitude of single-station earthquake events not only using the waveforms of one station，but also those of multi-station in the network. Taking the larger aftershocks with high signal noise ratio as template，we detect phase arrival times of single-station earthquake events in multi-station using waveform cross-correlation phase detection technique. Therefore we can estimate the location and magnitude based on multi-station phase arrival times and amplitude ratios by using waveform cross-correlation phase detection technique. Then the formula between the minimum completeness magnitude and time is obtained by catalogue completeness analysis. Comparison with artificial phase picking error as well as the magnitude repetition estimation result indicate that the phase detection and magnitude estimation results in this paper are reliable. In total we obtained the magnitude estimation of 253 single-station events and epicentral location of 177 events. The spatial distribution of single-station earthquakes is consistent with the distribution of other aftershocks. However，the magnitude of single-station earthquakes occurred in a short time after the main shock or the largest aftershock are underestimated in catalogue，which may be affected by the interference of subsequent phase of the main shock and the biggest aftershock and interaction of aftershocks. In the time interval between 0.02 days and 0.3 days after the main shock，the minimum completeness magnitude exhibits a linear decreasing with time in log，and then becomes stable at about ML1.1 after 0.3 days since the main shock. |
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