RISP系统在2018年台湾海峡MS6.2地震序列中的应用研究

Application of RISP System to MS6.2 Taiwan Strait Earthquake Sequence in 2018

摘要:

为评估实时智能地震处理系统（RISP）对台网条件较差海域地震序列的处理能力，离线处理了 2018 年 11 月 26 日台湾海峡 M_S6.2地震前后 21 天的连续波形数据，对比分析了自动处理结果与人工编目结果，定量评估了系统产出自动地震目录的完备性以及震源位置、震级大小、震相到时等信息的可靠性。系统共产出 407 条台湾海峡地震目录，与人工多台目录匹配 93 条，匹配率为 100%；与人工单台目录匹配 200 条，匹配率为 93.9%；其余 114 条地震目录均为人工漏分析的台湾海峡地震序列事件。匹配事件地震参数统计结果表明，发震时刻偏差小于 1.0 s 占比 96.77%；震中位置偏差小于 10 km 占比 100%；震源深度偏差小于 10 km 占比 50.54%；震级偏差小于 0.5 占比 98.92%。RISP 系统可快速产出台湾海峡地震序列目录，目录完备性明显优于人工目录，地震参数的精度与人工目录相当。利用系统自动处理结果反演主震震源机制解，并对 M_L≥3.0 的地震进行精定位，认为台湾海峡 MS6.2 地震发震构造可能为一条近东西向的隐伏断裂。RISP 系统自动处理结果可用于快速判断发震断层，服务于地震预测预报、地震应急处置等工作。根据 RISP 系统产出地震序列分布特征以及主震震源机制解对于了解本次地震序列发震构造等研究具有重要意义。

Abstract:

To evaluate the performance of the Real-Time Intelligent Seismic Processing (RISP) system in processing earthquake sequences in marine areas with poor seismic station coverage, continuous waveform data for 21 days before and after the M_S6.2 earthquake in the Taiwan Strait on November 26, 2018, were processed offline. A comparative analysis was conducted between the automated processing results and manual cataloging results. The completeness of the automated earthquake catalogs generated by the system and the reliability of parameters, including hypocenter location, magnitude, and seismic phase arrival time, were quantitatively evaluated. A total of 407 earthquake catalogs were generated by the RISP system. Among these, 93 matched the multi-station manual catalogs (100% matching rate), and 200 matched the single-station manual catalogs (93.9% matching rate). The remaining 114 catalogs were events of the Taiwan Strait earthquake sequence that were undetected by manual cataloging. Statistical results of the matched events showed that 96.77% had origin time deviations less than 1.0 s, 100% showed epicenter location deviations less than 10 km, 50.54% had focal depth deviations less than 10 km, and 98.92% exhibited magnitude deviations less than 0.5. The RISP system could rapidly generate earthquake sequence catalogs for the Taiwan strait, with significantly better completeness than manual cataloging and comparable accuracy of seismic parameters to manual cataloging. Using the automated processing results, this study inverted the focal mechanism solution of the mainshock and performed precise relocation for earthquakes with M_L≥3.0. It was believed that the seismogenic structure of MS6.2 Taiwan Strait earthquake was likely an east-west trending blind fault. The automated processing results of the RISP system enable rapid identification of seismogenic faults, providing support for earthquake prediction and forecasting, along with emergency response operations. The distribution characteristics of the earthquake sequence and the focal mechanism of the mainshock generated by the RISP are of great significance for understanding the seismogenic structure of this earthquake sequence.