Ground motion acceleration and response spectra of Al-Mashair area, Makkah Al-Mukarramah, Saudi Arabia

Abstract

The residential buildings of Makkah Al-Mukarramah constructed mostly on a soft Quaternary deposits with various thicknesses reaching to more than 30 m in most districts. The spatial variation of ground motion in Al-Mashair area has been assessed by synthetic ground motion acceleration using a point source model coupled by a site response analysis. The bedrock level acceleration time histories have been generated at 27 sites within Al-Mashair area generated by earthquake of 5.0 moment magnitude, using a synthetic ground motion model. While, the ground surface response spectral curves with 5% of the critical damping were assessed using shear-wave velocity profiles of multichannel analysis of surface waves besides the earthquake time histories. Surface ground response spectra were mapped using the ArcGIS platform for 1.5 Hz, 3.0 Hz, 5.0 Hz, 8 Hz, and 10 Hz where this frequency range includes the range of natural frequencies of tall to single story buildings. The surface ground motion maps display that the hazard level ranges from low to moderate, where peak spectral acceleration varies between 13 cm/s2 and 124 cm/s2. The maximum surface ground motion values are calculated with 5% damped horizontal spectral acceleration at 10 Hz, which is equal to the natural frequency of low-rise buildings. These results should be taken into consideration from decision-makers, urban planners, and civil engineers during the design of earthquake-resistant structures in Makkah Al-Mukarramah city in general and Al-Mashair zone in particular.