Estimation of the Site Effect Using Microtremor Technique at New Akhmim City, Akhmim, Sohag, Egypt

Abstract

Abstract —Local site effect is a significant aspect of seismic hazards, which often causes amplification of ground motions and results in increase in the damage potential of an earthquake. This article displays an experimental study of microtremors data to investigate the dynamic characteristics of the soil and structures in the desert zone of Akhmim City, east of River Nile, Sohag governorate, Egypt. Because of progressive population growth in the Nile valley and delta regions, the Egyptian Governorate considered increasing the number of new communities, especially in the Sohag district, to improve the living conditions. The study area is one of the new urban areas which was suggested by Egyptian Urban Communities Authority (EUCA). For this purpose, the horizontal to vertical (H/V) spectral ratio was used to provide precious information about the soil properties and its engineering features for foundation purposes. The H/V spectral ratio analyses of ambient noise data at the measurement stations were processed and interpreted using Geopsy Software to calculate the amplification factor and fundamental resonance frequency at each observation point. The results indicate that the resonance frequency ranges between 0.21 and 0.28 Hz at the most of the measurement stations, with some irregularities at stations No. 2 and 4 because of the higher softness of sediments in these locations. Most of lower fundamental frequencies are observed in the southern part of the study area, whereas higher values are observed in the northern part of the study area. The amplification factor ranges between 1.38 and 4.15. Higher values were recorded in the northeastern and southern parts, while lower ones were observed in the northwestern and southwestern parts of the mapped area. It can be concluded that the amplification component increases with increasing softness of the sediments. Interpretation of fundamental frequency distribution map is very significant to estimate the building heights and the number of stories, which was estimated to be 35 to 47.