On the influence of site conditions and earthquake magnitude on ground-motion within-earthquake correlation: analysis of PGA data from TSMIP (Taiwan) network
On the influence of site conditions and earthquake magnitude on ground-motion within-earthquake correlation: analysis of PGA data from TSMIP (Taiwan) network
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DOI：
10.1007/s10518-012-9368-5
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发表时间：
2012-08
影响因子：
4.6
通讯作者：
V. Sokolov;F. Wenzel;K. Wen;W. Jean
中科院分区：
文献类型：
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作者：
V. Sokolov;F. Wenzel;K. Wen;W. Jean
我们利用台湾强震仪器计划台网1993-2009年台网所积累的强震记录，分析了地震动的震内相关性。利用最近建立的两个基于矩、震级和震源距离的地震动峰值加速度预测方程，计算和分析了该地区的地震动残差。我们还使用了TSMIP站点土壤柱顶部30 m （Vs30）平均横波速度数据数据库。我们表明，地震内相关性可能会因场地类别、该地区的总体地质特征和地震震级而显著变化，这些记录在分析的数据集中占主导地位。一方面，对于特定的地质构造（如沉积充填盆地和大面积平原区），PGA残差的震内相关性与v30值的空间相关性具有显著的对应关系；另一方面，高水平的地震动相关性（或残差的显著非随机成分）可能是由于软表土和厚沉积物的共同影响以及路径或方位效应造成的。扩展断层的点源近似和忽略上、下壁效应也可能导致非随机残差。应用经验校正因子，考虑地震的震级、震源到站点的距离和给定台站的Vs30值，可以有效地降低震内相关水平，以及震内标准差。分析结果可用于台湾以及其他具有类似地质特征地区的空间分布结构（组合、生命线）的地震危险性、破坏和损失的实际估计。
We analysed the within-earthquake correlation of ground motion using the strong-motion records accumulated by the TSMIP (Taiwan Strong Motion Instrumentation Program) network in Taiwan during 1993–2009. Two ground-motion prediction equations, which were recently developed for peak ground acceleration (PGA) in the region and based on moment and local magnitude and hypocentral distance, were used for the calculation and analysis of ground-motion residuals. We also used the database containing shear-wave velocity data averaged for the top 30 m of the soil column (Vs30) for the TSMIP stations. We showed that the within-earthquake correlation may vary significantly depending on site classes, gross geological features of the area, and magnitude of earthquakes, records of which dominate the analysed dataset. On the one hand, there is a prominent correspondence between the within-earthquake correlation of PGA residuals and spatial correlation of Vs30 values, which was estimated for particular geological structures (e.g., sedimentary filled basins and large plain areas). On the other hand, the high level of ground-motion correlation (or significant non-random component of residuals) may be caused by the joint influence of soft surface soil and thick sediments and by the path or azimuthal effects. The point-source approximation of extended fault and neglected hanging- and foot-wall effects may also result in non-random residuals. The application of empirical correction factors, which consider the magnitude of earthquakes, source-to-site distance and Vs30 value for given stations, allows for the effective reduction in the level of within-earthquake correlation, as well as the within-earthquake standard deviation. The results of the analysis may be used in practical estimates of seismic hazard, damage and loss for spatially distributed structures (portfolios, lifelines) in Taiwan, as well in other regions with similar geological characteristics.