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实时断层破裂尺度估计方法——以2016年M_W 7.0熊本地震为例
Real-Time Fault Rupture Scale Estimation Method——A Case Study of the 2016 M_W 7.0 Kumamoto Earthquake
【摘要】 实时估计地震震源参数并结合地震动预测方程进行地震动场预测,是地震预警系统中最常用且具有最高时效性的方法。对于中-大型地震而言,由于断层有限性效应的影响,获得准确的震源参数(震级、断层长度、断层走向以及单双侧破裂的比例系数)是影响该方法效能的关键因素。介绍一种针对大震的实时断层破裂尺度估计方法,包括主断层的破裂方向以及破裂长度,可用于实时地震动预测以及近实时地震影响场的绘制。通过最小化观测地震动参数值与加入断层模型参数后的理论预测值之间的误差函数,来确定最佳线源模型。通过实时追踪断层破裂情况,并对源模型进行校正,可以显著改善大震时传统点源模型对近断层区域的低估。同时,引入赤池信息准则可以自动判别何时使用线源模型,从而更加准确地预测地震动场。此方法作为传统预警方法面对大震时的补充,不仅不改变时效性,而且能够提高预测精度。使用2016年熊本M_w 7.0地震对方法进行测试。结果表明,约在13 s左右,断层模型的角度开始收敛,在18 s后加入线源模型可以显著提高预测精度。这种方法能够快速准确地估计此次地震的震级和断层破裂参数,并具有很好的稳定性。
【Abstract】 Real-time estimation of earthquake source parameters combined with ground motion prediction equations for ground motion field prediction is the most commonly used and most time-efficient method in earthquake early warning systems. For medium to large earthquakes, obtaining accurate source parameters(magnitude, fault length, fault strike, and the proportion of unilateral or bilateral rupture) is a crucial factor affecting the effectiveness of this method, due to the influence of finite fault effect. A real-time fault rupture scale estimation method for large earthquakes was introduced, including the rupture direction and rupture length of the main fault, which can be used for real-time ground motion prediction and near-real-time seismic influence field mapping. The optimal line source model was determined by minimizing the error function between the observed ground motion parameters and the theoretical predicted values incorporating fault model parameters. By real-time tracking of fault rupture and correcting the source model, the underestimation of near-fault regions by traditional point source models during large earthquakes could be significantly improved. Furthermore, the introduction of the Akaike Information Criterion could automatically determine when to use the line source model, so as to predict the ground motion field more accurately. As a supplement to traditional early warning methods for large earthquakes, this method not only maintained the timeliness but also improved the prediction accuracy. The method was tested in the 2016 M_w 7.0 Kumamoto earthquake.The results showed that at approximately 13 seconds, the angle of the fault model began to converge and adding the line source model after 18 seconds significantly improved the prediction accuracy. This method can rapidly and accurately estimate the magnitude and fault rupture parameters of the earthquake and demonstrates good stability.
【Key words】 earthquake early warning; ground motion prediction equation; rupture scale estimation; fault distance;
- 【文献出处】 防灾减灾工程学报 ,Journal of Disaster Prevention and Mitigation Engineering , 编辑部邮箱 ,2024年06期
- 【分类号】P315.7
- 【下载频次】14