Site effect evaluation for Yanbu City urban expansion zones, western Saudi Arabia, using microtremor analysis
- PDF / 1,324,330 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 65 Downloads / 216 Views
ORIGINAL PAPER
Site effect evaluation for Yanbu City urban expansion zones, western Saudi Arabia, using microtremor analysis K. Alyousef & A. Al-Amri & M. Fnais & Kamal Abdelrahman & Oumar Loni
Received: 14 November 2013 / Accepted: 23 January 2014 # Saudi Society for Geosciences 2014
Abstract Recently, Yanbu City has been greatly growing; great developmental projects, urban community settlements, and petrochemical industries have been established. Historical and instrumental earthquakes were felt by this city, such as the earthquake on 19 May 2009 which was a moderate earthquake (moment magnitude (Mw) 5.7) whose ground motions have affected some building structures. Yanbu City has been divided by a grid of points separated by about 500 m, and microtremor measurements have been conducted at 141 measuring sites. The acquired data have been processed using worldwide Geopsy software package to calculate the fundamental frequency peaks and their corresponding amplification factors. The natural origin of these peaks has been confirmed. Based on fundamental frequency (f0), Yanbu City has been classified into three zones—from 0.13 to 1.0 Hz in the first zone, from 1.0 to 4.0 Hz in the second zone, and from 4.0 to 7.6 Hz in the third zone. The coastal zone of Yanbu illustrates smaller values of f0 that reflect great thickness of soft sediments while the eastern zone presents an opposite phenomenon. Accordingly, high-rise buildings in the coastal zone will be affected greatly by low frequencies originating from distant earthquakes. Most of Yanbu City has f0 values in the range of 1.0–4.0 Hz. Furthermore, bedrock ground motion could
K. Alyousef : O. Loni King Abdulaziz City for Science and Technology, Riyadh, Kingdom of Saudi Arabia A. Al-Amri : M. Fnais : K. Abdelrahman (*) Geology and Geophysics Department, King Saud University, Riyadh, Kingdom of Saudi Arabia e-mail: [email protected] K. Abdelrahman Seismology Department, National Research Institute of Astronomy and Geophysics, Cairo, Egypt
amplify as much as three times. This indicates that one- to three-story buildings in Yanbu City are vulnerable to hazardous resonant shaking from local and near earthquakes. Keywords Soft sediments . Microtremor . Predominant frequency . Amplification factor . Yanbu City
Introduction Yanbu City is one of the oldest marine ports along the western coast of Saudi Arabia (Fig. 1) and lies at latitude 24°0.5′ 07.27″ N and longitude 38°03′28.47″ E. In recent times, this city attracted several projects for development and urban expansion. In 1068, Yanbu was affected by a historical earthquake of intensity VI (El-Isa and Al-Shanti 1989; Ambraseys et al. 1994). Furthermore, on 19 May 2009, the city was affected by an earthquake of moment magnitude (Mw) 5.7, with an epicenter located about 100 km northeast of the city, followed by a huge number of aftershocks with a maximum magnitude of 4.2. Some structures at Yanbu City have been affected, and slight damage was documented for two and/or three building structures. Therefore, the evalua
Data Loading...
