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

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.