An Investigation into the Ground Motion Amplification Potential of Selected Sites of Addis Ababa City

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Date

2018-07

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Publisher

AAU

Abstract

Located on the western margin of the Main Ethiopian Rift, Addis Ababa, the capital city of Ethiopia, has experienced a number of earthquakes since its establishment. Thick soil formations which are predicted to have an effect on ground motion parameters characterize portions of the city. This site effect is even more significant considering the fact that the city is located in a region characterized by moderate seismicity. A one-dimensional ground response analysis using equivalent linear method was conducted to investigate the influence of selected sites on input ground motions. Input soil data were acquired from geotechnical investigation reports and seismic refraction surveys to characterize the soil profile of the selected sites. By considering the geologic and tectonic conditions of the vicinity, input ground motions were selected from PEER ground motion database. Ground motions of unique parameters that are customarily used in engineering practices were also included. Ground response analyses were performed employing the input soil data to the DEEPSOIL program subjected to the selected input ground motions at the base of the soil profile. The outcomes of the analyses show that the selected sites have significant potential of amplifying the ground motions. This amplification effect is observed to be exceedingly higher than the up-to-date code-specified predictions. Therefore, the study suggests that it would be worth investigating further in order to come up with more comprehensive study.

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Keywords

Ground Motion, Addis Ababa City, Amplification, Ethiopian Rift

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