Abstract Long-period pulse-like ground motions in the near-field are likely to induce severe damage to large structures due to resonance at the natural frequencies of engineered construction. To investigate the origin and characteristics of large velocity pulses from the seismic source, this study identifies 14 stations with velocity pulses from 32 strong-motion seismographs located in the near-field of the Imperial Valley MW 6.5 earthquake. The pulse-like ground motions are simulated by a kinematic approach using a fourth-order accurate finite-difference method. The results show that the slip asperity in the northern part of the fault plane contributes more to large velocity pulses than the asperity that originates in the hypocentral zone. The two-sided pulses on the fault-normal component and the one-sided pulses on the fault-parallel component are mainly regulated by the fault rupture and slip directions, respectively. Compared with the pseudo-velocity response spectrum, the displacement response spectrum better captures the resonance effect of long-period pulse-like ground motion on large structures. The location of the maximum ground motion coincides with the surface projection area of the large asperity, and the amplitude and the attenuation rate of each horizontal component vary with increasing distance from the fault. The difference in the ground motion peaks on both sides of the fault implies that the fault-normal component is more sensitive to the fault dip angle than the fault-parallel component. We reproduce the pulse-like ground motions up to 1 Hz by fitting the simulated velocity time histories, response spectrum and ground motions to observed data. Using the pulse records of the Imperial Valley earthquake, the 1994 Northridge MW 6.7 earthquake, and the 1999 Chi-Chi MW 7.6 earthquake, we compare the effects of earthquake magnitude on peak value and distribution of large velocity pulses, in which a reasonable consistency can be observed. Our simulated results of near-field pulse-like ground motions are beneficial to clarify the pulse mechanism.

中文翻译：

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模拟加利福尼亚州帝王谷地震的近场脉冲式地面运动

摘要 近场中的长周期脉冲式地面运动可能会由于工程结构固有频率的共振而对大型结构造成严重损坏。为了研究震源大速度脉冲的起源和特征，本研究从位于帝王谷 MW 6.5 地震近场的 32 个强震地震仪中确定了 14 个具有速度脉冲的台站。使用四阶精确有限差分法通过运动学方法模拟脉冲状地面运动。结果表明，断层平面北部的滑动粗糙比起源于震源区的粗糙对大速度脉冲的贡献更大。断层正常分量上的两侧脉冲和断层平行分量上的一侧脉冲分别主要受断层破裂和滑动方向的调节。与伪速度响应谱相比，位移响应谱更好地捕捉了长周期脉冲状地震动对大型结构的共振效应。最大地震动的位置与大凹凸不平的地表投影面积重合，每个水平分量的振幅和衰减率随着距断层距离的增加而变化。断层两侧地震动峰值的差异意味着断层法向分量比断层平行分量对断层倾角更敏感。我们通过将模拟速度时间历程、响应谱和地面运动与观测数据拟合，重现高达 1 Hz 的脉冲状地面运动。利用帝王谷地震、1994年北岭6.7级地震和1999年集集7.6级地震的脉冲记录，比较了震级对大速度脉冲峰值和分布的影响，其中合理的一致性可以被观察。我们对近场类脉冲地面运动的模拟结果有利于阐明脉冲机制。我们比较了地震震级对大速度脉冲峰值和分布的影响，其中可以观察到合理的一致性。我们对近场类脉冲地面运动的模拟结果有利于阐明脉冲机制。我们比较了地震震级对大速度脉冲峰值和分布的影响，其中可以观察到合理的一致性。我们对近场类脉冲地面运动的模拟结果有利于阐明脉冲机制。