翡翠河谷地震动地形效应解析分析

Analytical study on the topographic effect on ground motion of Feitsui canyon

  • 摘要: 地表不规则地形的存在往往会引起地震波的散射,进而产生局部地震动放大或衰减的现象。虽然地形效应最早在异常地震记录中被发现,然而利用地形影响台阵记录到的地震动数据却少之又少。基于1992年在我国台湾翡翠河谷上观测到的六条地形影响台阵记录,利用线源SH波入射下非对称V形河谷地震波传播解析理论,模拟得到了河谷台阵各点的地震动,揭示了翡翠河谷地形效应对地震动影响的规律。与实测记录的对比结果表明利用笔者提出的地震波传播解析理论能够较好地反映河谷地形对地震动的影响。

     

    Abstract: The local amplification or attenuation of ground motion is often caused by the surface irregular topography, which is due to the scattering phenomenon when the seismic wave propagates to the local topography. Although the topographic effect was first discovered in the anomalous seismic records, the ground motion data recorded by the topographic influence array are very few. There are five earthquakes recorded by six strong-motion accelerometers deployed along the Feitsui canyon recorded from the Hualien earthquake in 1992. Using our analytical theory of seismic wave propagation around a non-symmetrical V-shaped canyon excited by a line source of SH waves, the strong motion accelerations of the site were simulated. The influences of topographic effect on the ground motion of the Feitsui canyon are revealed. The comparison between the simulated results and those ground motion accelerations recorded indicates that the proposed analytical theory of seismic wave propagation around V-shaped canyon is suitable for simulating the topographic effects on ground motions.

     

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