2019 Ridgecrest Earthquake Reveals Areas of Los Angeles That Amplify Shaking of High-Rises
2019 Ridgecrest Earthquake Reveals Areas of Los Angeles That Amplify Shaking of High-Rises
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2019 年里奇克莱斯特地震揭示了洛杉矶部分地区高层建筑摇晃加剧的情况
DOI：
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发表时间：
2020
影响因子：
3.3
通讯作者：
K. Chandy
中科院分区：
文献类型：
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作者：
M. Kohler;Filippos Filippitzis;T. Heaton;R. Clayton;Richard Guy;J. Bunn;K. Chandy
2019年7月6日，加利福尼亚州洛杉矶市以北200公里的里奇克雷斯特市发生7.1级地震，震惊了该市的民众。虽然地震没有对洛杉矶造成破坏，但与矮小建筑的摇晃感觉形成对比的是，高层建筑的体验令人恐惧。560个地面加速计的观测显示，洛杉矶盆地发生了超过2分钟的震动，变化很大。观测数据来自空间密集的社区地震网络(CSN)，以及较为稀疏的南加州地震网络和加州强震仪器计划网络。S的1、3、6和8个周期的场地放大系数是每个台站在两个水平方向上的反应谱值之和相对于三个基岩场地的平均值的比率。位置放大的空间相干行为出现在≥3 S周期，并且计算的最大位置放大是最大的，分别是S 3，6和8周期的7，10和8倍。密集的CSN观测表明，长周期放大与到基底的深度明显相关，但只是部分相关。长周期放大作用最大的地点(≥3 S)并不靠近盆地最深的部分。在6和8个S期，最大放大出现在洛杉矶盆地西部和圣费尔南多河谷中南部沉积盆地。这些观察表明，假设的高层建筑位于一个以站点放大最大为特征的地区，其激发强度可能是洛杉矶市中心的四倍。
The populace of Los Angeles, California, was startled by shaking from the M 7.1 earthquake that struck the city of Ridgecrest located 200 km to the north on 6 July 2019. Although the earthquake did not cause damage in Los Angeles, the experience in high-rise buildings was frightening in contrast to the shaking felt in short buildings. Observations from 560 ground-level accelerometers reveal large variations in shaking in the Los Angeles basin that occurred for more than 2 min. The observations come from the spatially dense Community Seismic Network (CSN), combined with the sparser Southern California Seismic Network and California Strong Motion Instrumentation Program networks. Site amplification factors for periods of 1, 3, 6, and 8 s are computed as the ratio of each station’s response spectral values combined for the two horizontal directions, relative to the average of three bedrock sites. Spatially coherent behavior in site amplification emerges for periods ≥3 s, and the maximum calculated site amplifications are the largest, by factors of 7, 10, and 8, respectively, for 3, 6, and 8 s periods. The dense CSN observations show that the long-period amplification is clearly, but only partially, correlated with the depth to basement. Sites with the largest amplifications for the long periods (≥3 s) are not close to the deepest portion of the basin. At 6 and 8 s periods, the maximum amplifications occur in the western part of the Los Angeles basin and in the south-central San Fernando Valley sedimentary basin. The observations suggest that the excitation of a hypothetical high-rise located in an area characterized by the largest site amplifications could be four times larger than in a downtown Los Angeles location.