AI 中文总结
该研究采用3862条地震记录，建立了走滑与逆冲型地震的方向性概率模型，发现走滑型地震极化程度及RotD100/RotD50比值更高，可用于地震风险评估等场景。
AI 中文摘要
水平地震动的振幅会随方位变化发生显著改变。尽管断层错动类型对地震动强度集中趋势指标（如RotD50）的影响在地震动模型中已得到充分证实，但关于错动机制如何影响地震动完整方向性特征的研究却较少受到关注。本研究针对这一空白，采用3862条矩震级大于5的地震记录，对走滑型和逆冲型地震的地震动方向性进行了全面的概率表征。在0.01至10秒的58个振荡器周期范围内，考察了两个方向性参数：分别为非冗余方位下的伪加速度反应谱序数，经RotD100或RotD50强度归一化后（分别记为η和ν）。采用非线性回归方法，为这些参数的几何均值、对数标准差及完整概率分布建立了特定错动机制的模型。结果表明，走滑型地震的方向性与逆冲型地震存在显著差异，尤其在长周期阶段。在0.5秒以上的周期，走滑型地震的极化程度平均比逆冲型地震高1%至44%，且其RotD100/RotD50比值大1%至3.7%。所建立的模型使工程师和工程地震学家能够获取特定方位下伪加速度反应谱序数的特定错动机制估计值，适用于区域地震风险评估、特定方位的概率地震危险性分析等应用场景。
英文摘要
Horizontal earthquake ground motions exhibit substantial changes in amplitude with changes in orientation. While the effects of style of faulting on central tendency measures of ground motion intensity such as RotD50 are well established in ground motion models, less attention has been given to how faulting mechanism influences the complete directional characteristics of ground motions. This study addresses this gap by conducting a comprehensive probabilistic characterization of ground motion directionality for strike-slip and reverse-slip earthquakes using 3,862 records with moment magnitudes greater than five. Two directionality parameters were examined across 58 oscillator periods ranging from 0.01 to 10 s. The directionality parameters examined consist of pseudo-acceleration response spectral ordinates at all non-redundant orientations normalized by either RotD100 or RotD50 intensities (denoted as η and ν, respectively). Nonlinear regression was used to develop mechanism-specific models for the geometric mean, logarithmic standard deviations, and full probability distributions of these parameters. Results show that strike-slip earthquakes exhibit notably different directionality compared to reverse-slip earthquakes, particularly at longer periods. Strike-slip earthquakes are, on average, 1% to 44% more polarized than reverse-slip earthquakes at periods above 0.5 s, and have RotD100/RotD50 ratios that are 1% to 3.7% larger. The developed models enable engineers and engineering seismologists to obtain mechanism-specific estimates of pseudo-acceleration response spectral ordinates at specific orientations, for applications such as regional seismic risk assessments and orientation-specific probabilistic seismic hazard analyses.
Comments37 pages, 14 figures, submitted to Bulletin of the Seismological Society of America
