Microseismic zonation maps for Egypt using shear wave velocity ($ V_{s} $ 30), and standard penetration resistance value ($ N

Microseismic zonation maps for Egypt using shear wave velocity ($ V_{s} $ 30), and standard penetration resistance value ($ N_{30} $)

Gamal, Mohamed A. / Elhussein, Mahmoud

Abstract

Abstract Although Egypt has not been subjected to high seismic hazards, it does face a very high level of risk on this front. Even a small earthquake of moderate magnitude, such as the Faiyum earthquake of 1992 (Ms = 5.2), may turn into a catastrophic event causing collapse of or irreparable damage to thousands of buildings. This vulnerability is due to the country’s lack of seismic site classifications and bad engineering conditions of buildings, especially in villages. A total of 71 drilling boreholes and about 82 shear wave seismic velocity tests varying between the Downhole, Crosshole, Refraction Microtremors (ReMi), and Multichannel Analysis Surface Waves (MASW) methods were used to prepare the microseismic zonation maps for Egypt. Microseismic zonation maps were introduced using the geological map of Egypt, NEHRP Seismic site classifications based on “shear wave velocity” ($ V_{s} $ 30), and the “soil refusal depth map” (SPT ($ N_{30} $) = 50). Furthermore, new empirical equations to obtain $ V_{s} $ 30 versus SPT ($ N_{30} $) were introduced to help engineers and seismologists obtain the desired dynamic properties of the soil, such as the dynamic shear modulus (G). The seismic activities inside the Egyptian plate were combined with the microseismic zonation maps to analyze the important seismic hazards; this was done for variable soils. The present study is expected to be a regional reference for the expected shear wave velocity, SPT ($ N_{30} $) value, and shear rigidity constant for the different Egyptian soils and to help in the developing projects.