Abstract
Landslide susceptibility of Makkah Al-Mukarramah has been assessed by collecting microtremor measurements at 277 sites covering the whole area. These data were then processed and analyzed using the horizontal–vertical spectral ratio (HVSR) method to obtain the resonance frequency and H/V amplification factor. The results display that the predominant frequency values range between 0.26 and 17.27 Hz, and the amplification factor varies from 0.87 to 14.68. Then, 34 sites were selected to assess the frequency, amplitude and azimuthal site response where frequency ranges from 0.26 to 13.67 Hz while amplitude varies from 2.0 to 12.2. Moreover, the site response direction was parallel to the landslide directional response in the sliding areas which indicates that the site response direction followed the landslide direction. The results of this study have been approved practically at several sites through field measurements at some of recent landslide occurrence locations in Makkah urban area. These results signifying that microtremor measurements are effective technique in locating the sites suffering landslides, which, in turn, reduce their hazardous impact on either human-life and their beings. Therefore, it is highly recommended to apply this approach in places prone to landslides in southwestern Saudi Arabia.