Broadband Ground-Motion Simulation Using a Hybrid Approach
Broadband Ground-Motion Simulation Using a Hybrid Approach
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DOI：
10.1785/0120100057
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发表时间：
2010-10-01
影响因子：
3
通讯作者：
Pitarka, Arben
中科院分区：
文献类型：
--
作者：
Graves, Robert W.;Pitarka, Arben
本文描述了对Graves和Pitarka（2004）的混合宽带地面运动模拟方法的改进，该方法结合了低频（f < 1hz）的确定性方法和高频（f < 1hz）的半随机方法。在我们的方法中，断层破裂是运动学的，并且包含了滑动、破裂速度和上升时间的空间异质性。规定的滑移分布被限制为遵循逆波数平方衰减，平均破裂速度被设置为局部横波速度的80%，然后调整该速度，使高滑移区域的破裂传播更快，低滑移区域的破裂传播更慢。我们使用一个类似kostrov的滑动率函数，其上升时间与滑动的平方根成正比，整个断层的平均上升时间受到经验约束。最近对大型地表破裂地震的观测表明，近地表的破裂传播速度降低，上升时间延长，我们通过在从地表延伸到5公里的区域中应用70%的破裂速度降低和2倍的上升时间来模拟。我们通过模拟帝国谷、洛马·普里塔、兰德斯和北岭地震的强震记录来证明该技术的保真度。
This paper describes refinements to the hybrid broadband ground-motion simulation methodology of Graves and Pitarka (2004), which combines a deterministic approach at low frequencies (f < 1 Hz) with a semistochastic approach at high frequencies (f > 1 Hz). In our approach, fault rupture is represented kinematically and incorporates spatial heterogeneity in slip, rupture speed, and rise time. The prescribed slip distribution is constrained to follow an inverse wavenumber-squared fall-off and the average rupture speed is set at 80% of the local shear-wave velocity, which is then adjusted such that the rupture propagates faster in regions of high slip and slower in regions of low slip. We use a Kostrov-like slip-rate function having a rise time proportional to the square root of slip, with the average rise time across the entire fault constrained empirically. Recent observations from large surface rupturing earthquakes indicate a reduction of rupture propagation speed and lengthening of rise time in the near surface, which we model by applying a 70% reduction of the rupture speed and increasing the rise time by a factor of 2 in a zone extending from the surface to a depth of 5 km. We demonstrate the fidelity of the technique by modeling the strong-motion recordings from the Imperial Valley, Loma Prieta, Landers, and Northridge earthquakes.