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2007年新潟县中越近海地震期间柏崎刈羽核电站遭受到极强的震动。该核电站周围密集的地震检波器阵观测到的加速度记录目前已对公众开放,将会提供有价值的资料。基于在主震及前震、余震中观测到的垂直阵记录,利用归一化输入输出最小化(NIOM)方法研究了S波速度随时间的变化。在地表下50m与50～100m的地层中,发现在主震的主运动期间S波速度显著降低,显示了非线性行为。然而在地表100m以下的基岩层中,观测到了近似线性的行为。并且发现在100m以内的地层中,主运动后不久S波速度增大,说明这些地层没有发生较大的液化。最后,基于得到的S波速度研究了剪切模量和剪应变之间的关系。地表层及中间层的归一化剪切模量(G/G0)降低到约0.2(应变水平1×10-3～1×10-2)和0.6(在应变水平1×10-3～2×10-3)。
In 2007 Niigata Prefecture during the Sino-Vietnamese maritime earthquake in Kashiwazaki Kariwa Nuclear Power Plant suffered strong vibration. The acceleration records observed by the dense geophone array surrounding the nuclear power station are now open to the public and will provide valuable information. Based on the vertical array records observed in the main and foreshocks and aftershocks, the variation of S-wave velocity with time was studied using the normalized input-output minimization (NIOM) method. In the formations 50m and 50 ~ 100m below the subsurface, it was found that the S-wave velocity decreased significantly during the main motion of the main shock and showed a non-linear behavior. However, in the bedrock below 100m on the ground surface, an approximately linear behavior was observed. And it is found that in the strata below 100m, the S-wave velocity increases shortly after the main motion, indicating that no large liquefaction occurred in these strata. Finally, the relationship between shear modulus and shear strain was studied based on the S-wave velocity obtained. The normalized shear modulus (G / G0) of the surface and middle layers was reduced to about 0.2 (strain level 1 × 10-3 to 1 × 10-2) and 0.6 (strain level 1 × 10-3 to 2 × 10-3).