尚园程,史保平. 2020. 基于经验模型分析2018年2月台湾花莲地震序列特征及其前震的成因机制. 地震学报,42(1):1−11. doi:10.11939/jass.20190058. doi: 10.11939/jass.20190058
引用本文: 尚园程,史保平. 2020. 基于经验模型分析2018年2月台湾花莲地震序列特征及其前震的成因机制. 地震学报,42(1):1−11. doi:10.11939/jass.20190058. doi: 10.11939/jass.20190058
Shang Y C,Shi B P. 2020. Statistical analysis of the February 2018 Hualien,Taiwan,China,earthquake sequence:The features of its foreshocks,mainshocks,and aftershocks. Acta Seismologica Sinica42(1):1−11. doi:10.11939/jass.20190058. doi: 10.11939/jass.20190058
Citation: Shang Y C,Shi B P. 2020. Statistical analysis of the February 2018 Hualien,Taiwan,China,earthquake sequence:The features of its foreshocks,mainshocks,and aftershocks. Acta Seismologica Sinica42(1):1−11. doi:10.11939/jass.20190058. doi: 10.11939/jass.20190058

基于经验模型分析2018年2月台湾花莲地震序列特征及其前震的成因机制

Statistical analysis of the February 2018 Hualien,Taiwan,China,earthquake sequence:The features of its foreshocks,mainshocks,and aftershocks

  • 摘要: 利用地震学的三个经典经验模型(古登堡-里克特定律、修正的大森定律和巴特定律)和描述前震活动的Dieterich前震模型对2018年2月中国台湾花莲地震序列的特征进行了分析。将该地震序列分为ML5.5前震序列、ML5.5余震序列和ML6.0余震序列等3段子序列进行研究,结果显示:利用古登堡-里克特定律得到的ML5.5余震序列和ML6.0余震序列的b值近似为1,ML5.5前震序列的b值近似为0.5;利用修正的大森定律得到的ML5.5余震序列和ML6.0余震序列的p值近似为0.9;利用修正的巴特定律得出ML5.5余震序列和ML6.0余震序列的推定最大余震震级分别为ML5.0和ML5.5,与实际数据相比,其误差值约为0.1。通过拟合ML5.5前震的发生率,分析可得ML5.5前震序列的地震发生率\dot N正比于1/(tmt),其中t\ (t\text< t_\rmm)为前震发生时刻,t_\rmmML5.5地震发生时间,与Dieterich前震模型对前震现象的描述一致,表明其成因机制可能为主震成核过程中区域断层的次级断裂。

     

    Abstract: As we know, the statistical properties of an earthquake sequence are associated with three important empirical laws in seismology: Gutenberg-Richter law for the frequency-magnitude distribution, Båth law for the magnitude of the largest aftershock, and the modified Omori’s law for the temporal decay of aftershocks. In this paper these three laws are combined to study the February 2018 Hualien, Taiwan, China, earthquake sequence. In addition, a physics-based model proposed by Dieterich is used to describe the foreshock activities. The Hualien aftershock sequence is divided as three major sequences compounding with the ML5.5 foreshock sequence, the ML5.5 aftershock sequence and the ML6.0 sequence. The results indicate that the b values associated with Gutenberg-Richter law for the ML5.5 aftershock sequence and the ML6.0 aftershock sequence are approximately 1, respectively. And b value of the ML5.5 foreshock sequence are approximately 0.5. The p values with associated modified Omori’s law for the ML5.5 and ML6.0 aftershock sequences are both approximately 0.9, respectively. The estimated maximum aftershock magnitudes based on the modified form of Båth law are about ML5.0 and ML5.5, respectively, for ML5.5 and ML6.0 aftershock sequences, and the magnitude error is within \Delta M=0.1 with a comparison to the recorded events. We also find that, for the ML5.5 foreshock sequence, the seismicity rate \dot N increases as a function of 1/(tmt), where tt \text< t_\rmm) is the time of the foreshock and t_\rmm is the time when the ML5.5 earthquake occurred, respectively, which is consistent with the Dieterich earthquake triggering model, suggesting that the foreshock sequence may be related with mainshock nucleation process.

     

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