Numerical Site Spectral Amplification Due to Structural Control of Shallow Faults in Wadi Natash, Eastern Desert, Egypt

Abstract

Site spectral amplification patterns at Wadi Natash area are exhibited in three frequency band widths of 15 ~ 10 Hz, 10 ~ 7 Hz, and 7 ~ 5 Hz. These amplification patterns result from numerical two-dimensional equivalent linear simulations of propagating S -waves at 50 m depth. The S -wave's propagation direction is found to be parallel to the dipping direction of the fault plane. Additionally, the resulted amplification patterns above both normal and reverse faults tend to be highly dependent on the frequency band width and fault geometrical parameters. The maximum amplification factors indicate producing very high guided S -wave's energy in the overlying fault zone layers. The present results suggest that S -wave's guiding efficiency is strongly dependent on the fault type and its relevant parameters, such as fault zone width and fault continuity in layers, and on the frequency band width.