Oman Strong Motion Network (OSMN) and Site-specific Characterization for the Entire Strong Motion Stations in Muscat Region

Abstract

In 2001, the earthquake monitoring center (EMC) at Sultan Qaboos University (SQU) started monitoring earthquakes that occur in and around the sultanate of Oman through 10 short-period stations. The number of monitoring stations grew to 20 broadband seismic stations between 2004 and 2011 deployed in different parts of the sultanate. In 2014, EMC-SQU began an extensive project for updating and improving the monitoring network by adding 6 broadband stations and establishing a strong motion network consisting of 67 monitoring stations. This provides a good opportunity to investigate the influences of the seismic source, path, and site effects in the ground motion, particularly in the near-source area. Such data are essential for improving seismic hazard maps and consequently seismic building codes and earthquake-resistant design. A wide site selection survey was carried out for the entire proposed stations taking into account the standard site selection criteria. In order to use the strong motion recordings at their full potential, information on the site response at the recording site is needed. So, site investigation at 25 stations in Muscat region was performed in terms of noise level, resonance frequency (using horizontal-to-vertical spectral ratio (HVSR) method), P-wave velocity (using shallow seismic refraction tomography (SRT) technique), and S-wave velocity (using multichannel analysis of surface waves (MASW) tool), in addition to the available geotechnical boreholes. The results reflect the site classification in the light of NEHRP/IBC standards and consequently the seismic hazard level at the ground surface.