近地表沉积结构对爱因斯坦望远镜牛顿噪声的影响：一项二维数值研究
Effects of near-surface sedimentary structure on Newtonian noise for the Einstein Telescope: a 2-D numerical study
AI总结：
本研究通过二维黏弹性模拟发现，近地表沉积结构会影响爱因斯坦望远镜的牛顿噪声，其剪切波速、衰减及界面几何等特性会改变噪声的频谱特征，评估台址相关牛顿噪声时需明确考虑该结构，尤其针对200至300米深度的测试质量。
AI中文摘要：
近地表低速沉积物可强烈改变地震波场，进而影响地下引力波天文台的牛顿噪声估计。本研究通过二维黏弹性模拟（模拟硬岩基底上覆沉积层）探究这些效应，采用控制实验考察沉积层-基底界面几何形态、沉积物剪切波速、衰减特性及测试质量位置的影响。与均匀模型相比，沉积层会通过波捕获、干涉和衰减产生频率相关的变化：等厚沉积层产生比盆状界面更具横向相干性的波场和更尖锐的频谱增强；而横向厚度变化会拓宽并偏移响应。沉积物剪切波速主要控制频谱特征的频率，衰减则主要控制其振幅。牛顿噪声对位于沉积层内或其下方数百米处的测试质量的沉积结构最敏感，对沉积层厚度横向变化的敏感性随埋藏深度增加而降低，在本模型中2千米深度处敏感性较弱。这些结果表明，在评估与台址相关的牛顿噪声时，应明确考虑近地表沉积结构，尤其是针对埋藏于200米至300米深度之间的测试质量。
英文摘要：
Near-surface low-velocity sediments can strongly modify seismic wavefields and therefore affect estimates of Newtonian noise at underground gravitational-wave observatories. We investigate these effects using 2-D viscoelastic simulations of a sediment layer overlying hard-rock basement. Controlled experiments examine the influence of sediment-basement interface geometry, sediment shear-wave velocity, attenuation, and test-mass position. Relative to a homogeneous model, the sediment layer produces frequency-dependent changes through wave trapping, interference, and attenuation. A constant-thickness layer generates a more laterally coherent wavefield and a sharper spectral enhancement than a basin-shaped interface, whereas lateral thickness variations broaden and shift the response. Sediment shear-wave velocity primarily controls the frequencies of the spectral features, while attenuation mainly controls their amplitudes. Newtonian noise is most sensitive to sediment structure for test masses located within or several hundred meters below the sediment layer. The sensitivity to lateral variations in sediment thickness decreases with burial depth and is weak at 2 km depth in the present model. These results demonstrate that near-surface sedimentary structure should be represented explicitly when assessing site-dependent Newtonian noise, particularly for test masses located between 200 m and 300 m depths.
