Ground-Motion Characteristics and Nonlinear Soil Response Observed by DONET1 Seafloor Observation Network during the 2016 Southeast Off-Mie, Japan, Earthquake
Ground-Motion Characteristics and Nonlinear Soil Response Observed by DONET1 Seafloor Observation Network during the 2016 Southeast Off-Mie, Japan, Earthquake
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DOI：
10.1785/0120170296
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发表时间：
2019-06-01
影响因子：
3
通讯作者：
Aoi, Shin
中科院分区：
文献类型：
--
作者：
Kubo, Hisahiko;Nakamura, Takeshi;Aoi, Shin
2016年日本三重东南近海地震（M-JMA 6.5）的强烈地面运动由东海俯冲带的地震和海啸密集海底网络系统（DONET 1）海底观测网络记录。在0.5-8 s的周期在海底站的峰值地面速度和加速度反应谱（SA）的观测值远大于经验衰减关系预测的。观测值主要是由于强烈的现场放大效应，由于地下结构，如加积楔和浅软沉积物。另一方面，在峰值地面加速度和SA在0.12和0.25秒的周期的观测值遵循的经验关系，这是不一致的强烈的场地放大效应建议的频谱反演。为了理解这种不一致性，我们调查的非线性土壤响应DONET 1站在这一事件中使用时频分析和S波水平垂直频谱比。分析表明，在几个站点发生了显着的非线性土壤响应。这种非线性土壤行为在一定程度上抑制了2016年东南部三重地震期间DONET 1站的短周期地面运动放大。
Strong ground motions of the 2016 southeast off-Mie, Japan, earthquake (M-JMA 6.5) were recorded by the eastern Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET1) seafloor observation network in the Nankai subduction zone. The observed values in peak ground velocity and acceleration response spectra (SA) at periods of 0.5-8 s at seafloor stations were much larger than those predicted by the empirical attenuation relationship. The observed values were primarily caused by the strong site amplification effect due to the subsurface structure, such as an accretionary wedge and shallow soft sediments. On the other hand, the observed values in peak ground acceleration and SA at periods of 0.12 and 0.25 s follow the empirical relationship, which is inconsistent with the strong site amplification effect suggested by spectral inversion. To understand this inconsistency, we investigate the nonlinear soil response at DONET1 stations during this event using time-frequency analyses and S-wave horizontal-to-vertical spectral ratios. The analyses indicate that a significant nonlinear soil response occurred at several stations. This nonlinear soil behavior partially contributed to the suppression of the amplification of short-period ground motions at DONET1 stations during the 2016 southeast off-Mie earthquake.