Probabilistic seismic hazard assessment and site analyses of Arusha International Conference Centre (AICC), Arusha, Tanzania

Abstract

This work presents the evaluation of earthquake resistance of the Arusha International Conference Centre (AICC) complex, in Tanzania. The evaluation included probabilistic seismic hazard analysis (PSHA) and site response analysis. Seismic sources considered to constitute a seismic hazard in this study were randomly occurring seismicity located within five tectonic provinces around the site. For each province the seismic hazard is based on a cursory analysis of earthquake data from compiled ESARSWG bulletins and temporary deployed networks within the North Tanzania Divergence (NTD). Bedrock response signal together with the information of material characteristics from boreholes around the AICC site were used in analysis of site response. PSHA results indicated uniform hazard spectra values of 0.15, 0.2 and 0.27 g for return periods of 475, 975 and 2475 years, respectively. The surface ground response results indicated a maximum amplification factor of 3.7 and a spectral response of 4.5 g for a wave period of 0.6 sec that matches the natural frequency of the 6-7 storey buildings of the AICC complex. It is this resonance effect on the buildings that is assumed to have caused intense shaking in the earthquake of December 5th 2005 from Lake Tanganyika.

Keywords: Probabilistic seismic hazard analysis, Arusha International Conference Centre, East African Rift System, Uniform hazard spectra, Site effect