Site-specific Seismic Hazard Assessment to Establish Elastic design Properties for Chemical Plant, Salalah, Sultanate of Oman

Earthquakes are among the most life-threatening natural disasters, causing plenty of casualties, enormous economic losses, and disruption of services. The most effective way to decrease earthquake risk is to properly evaluate the seismic hazard and to use these results to enhance design and construction.

This study investigate site-specific seismic hazard assessment for a chemical plant project, Sultanate of Oman. It utilizes the Probabilistic Seismic Hazard Assessment (PSHA) approach to define the design criteria for this site. The seismic hazard calculation conducted at the bedrock conditions, and then the possible site-effects have been introduced into the bedrock hazard values in order to develop surface seismic hazard assessments.

The study provides seismic hazard values of Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), and Spectral Accelerations (SA) for 475, 975 and 2475 years return periods at the surface of the site. The results are based on the up-to-date earthquake catalog, seismic sources of the region as well as recent ground motion prediction equations. The highest spectral accelerations for 0.1, 0.2, and 1 sec spectral periods are 156, 119, and 31 cm/sec² for 475 years return period and 301, 192, and 48 cm/sec² for 2475 years return period. The study provides also time histories of the ground-motions at the surface for the above calculated hazard levels. Deaggregation analysis revealed that for all return periods, nearby moderate earthquakes dominates the seismic hazard for short spectral periods, while larger events at distance range 140-170 km dominate the seismic hazards for longer spectral periods.