A SEISMIC MICROZONATION USING MICROTREMOR AND SEISMIC DATA: SOHAG, EGYPT (A CASE STUDY)

Abstract

Microtremor measurements together with shallow seismic refraction survey have been conducted and found out to be an effective approach to study the site effect and also to establish a seismic hazard microzonation overview. The fundamental resonance frequency and amplification of ground motion at different frequencies were estimated using the microtremor data measured at ten sites in the new industrial zone around the urban areas in Sohag Governorate, Egypt. Also, site effects were calculated applying a numerical technique using shear wave velocities observed from 22 shallow seismic profiles measured at the study area utilizing 24-channel shallow seismic refraction seismograph. The results show variations in the fundamental resonance frequency values from one site to another depending on its distance from the Eocene plateau scarp that located at the southern and south western sides of the study area, where it becomes higher close to the plateau foot. In case of the low frequency, the amplification of the ground motion shows variation from site to the other site depending on its vicinity to the plateau, while in case of high frequency the variation depends on the thickness of the sediment layers. The given results using the microtremor technique showed a good matching with the results given by the shallow seismic refraction method.