罗诚, 谢俊举, 温增平. 2018: 熊本MW7.0地震近场地表与井下地震动对比研究. 地震学报, 40(1): 108-120. DOI: 10.11939/jass.20170111
引用本文: 罗诚, 谢俊举, 温增平. 2018: 熊本MW7.0地震近场地表与井下地震动对比研究. 地震学报, 40(1): 108-120. DOI: 10.11939/jass.20170111
Luo Cheng, Xie Junju, Wen Zengping. 2018: Comparison of near-field surface and borehole ground motion observed during the Kumamoto MW7.0 earthquake. Acta Seismologica Sinica, 40(1): 108-120. DOI: 10.11939/jass.20170111
Citation: Luo Cheng, Xie Junju, Wen Zengping. 2018: Comparison of near-field surface and borehole ground motion observed during the Kumamoto MW7.0 earthquake. Acta Seismologica Sinica, 40(1): 108-120. DOI: 10.11939/jass.20170111

熊本MW7.0地震近场地表与井下地震动对比研究

Comparison of near-field surface and borehole ground motion observed during the Kumamoto MW7.0 earthquake

  • 摘要: 选取日本熊本MW7.0地震断层距小于200 km的82个近场KiK-net台站记录到的三分量记录数据进行基线校正后,获得近场地面运动水平向的峰值加速度PGA、峰值速度PGV及周期为0.2,1,2,3,5和10 s的加速度反应谱数据,并与美国NGA-West2的地震动预测模型相比较,研究熊本地震地表和井下地震动峰值及反应谱的衰减特征,通过比较KiK-net台站地表与井下记录结果,探讨浅层场地放大效应的影响。研究结果表明:① 对于井下观测结果,NGA-West2的地震动模型对PGA和短周期0.2 s的反应谱的预测值与井下观测值相比整体偏高,而PGV和较长周期地震动(如1,2和3 s的反应谱)的预测值与井下观测值较为吻合;② 地表观测记录的PGA,PGV和周期为0.2—3 s的反应谱残差整体上随vS30对数值的增大呈线性减小的趋势,而周期为5 s和10 s的长周期部分,其场地效应的影响很小;③ 相对于井下记录,地表记录的地震动PGA,PGV和周期为0.2,1和2 s的反应谱有明显的放大,这种放大作用随浅层场地剪切波速的增大而减小;周期为3,5和10 s时长周期地震动的放大效应很小。

     

    Abstract: We used the records of 82 near-field strong motion stations (KiK-net), which are within 200 km to the rupture fault of the Kumamoto MW7.0 earthquake, as database to derive near-field horizontal peak ground acceleration PGA, peak ground velocity PGV and spectra acceleration (period T=0.2, 1, 2, 3, 5, 10 s), after baseline correction we further compared them with the NGA-West2 ground motion model predictions. We investigated the attenuation and residuals distribution characteristics of these intensity measures (IMs), and shallow site-amplification effects by comparing surface and borehole ground motion records. The following conclusions can be drawn from our study: In the boreholes, NGA-West2 predictions are obviously greater than observations of PGA and T=0.2 s spectra acceleration, but close to the measured value in long-period IMs (spectra acceleration with T=1, 2, 3 s) and PGV. On surface, the residuals of observed PGV and T=0.2–3 s spectra acceleration show linear decrease tendency with the increase ofvS30, but the site effects affect little on the long-period spectra acce-leration. Surface records are greater than borehole in PGA, PGV and T=0.2, 1, 2 s spectra acceleration, and the amplification effects decrease with the increase of shallow site shear velocity; whereas the site amplification has little effects on the long-period spectra acceleration with T=3, 5, 10 s.

     

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