Extreme Accelerations During Earthquakes Caused by Elastic Flapping Effect
Extreme Accelerations During Earthquakes Caused by Elastic Flapping Effect
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DOI：
10.1038/s41598-018-37716-y
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发表时间：
2019-02-04
影响因子：
4.6
通讯作者：
Damiano, Len
中科院分区：
文献类型：
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作者：
Goto, Hiroyuki;Kaneko, Yoshihiro;Damiano, Len
准确记录地震引起的地面大震动对我们理解地震物理学和地震危险性评估至关重要。位于新西兰南岛北部的WTMC地震台站在最近发生的7.8级凯库拉地震中记录到了极大的加速度，峰值为重力加速度的3.2倍。然而，产生如此大的加速度的机制还没有得到很好的理解。在这里，我们使用数值模拟来检验一系列可以再现观测到的加速度记录特征的物理模型。我们发现，在6.3级地震中观测到的不对称垂直加速度记录可以用扑动效应来解释，即安装传感器的基础板的局部弹性弹跳。我们的研究结果表明，WTMC地震台站记录的极大加速度并不能反映实际的地面震动，而是由传感器周围的局部系统响应引起的。我们的发现对基于凯库拉地震波形记录的未来地震危险性评估和所有地震易发国家强震检波器的安装方法都具有重要意义。
Accurate recording of large, earthquake-induced ground shaking is critical for our understanding of earthquake physics as well as seismic hazard assessment. Extremely large accelerations with the peak value of 3.2 times the gravity acceleration were recorded at seismic station WTMC located in northern South Island of New Zealand during the recent magnitude 7.8 Kaikoura earthquake. However, the mechanisms responsible for the generation of such large accelerations are not well understood. Here we use numerical simulations to examine a range of physical models that can reproduce the observed characteristics of the acceleration record. We find that the record of the asymmetric, vertical accelerations, also observed during a magnitude 6.3 earthquake, can be explained by a flapping effect, that is, the local, elastic bouncing of a foundation slab on which the sensor is installed. Our results suggest that the extremely large accelerations recorded at seismic station WTMC do not reflect the actual ground shaking, but were caused by a local, system response around the sensor. Our finding has important implications for both the evaluation of future seismic hazard based on the waveform records of the Kaikoura earthquake and the installation methodology of strong-motion seismometers in all earthquake prone countries.