Deaggregation of Probabilistic Ground Motions for Selected Jordanian Cities

Abstract

Probabilistic Seismic Hazard Analysis (PSHA) approach was adopted to investigate seismic hazard distribution across Jordan. Potential sources of seismic activities in the region were identified, and their earthquake recurrence relationships were developed from instrumental and historical data. Maps of peak ground acceleration and spectral accelerations (T=0.2 and T=1.0 sec.) of 2% and 10% probability of exceedance in 50 years were developed. This study deaggregated the PSHA results of 2% and 10% probability of exceedance in 50 years results of twelve Jordanian cities to help understand the relative control of these sources in terms of distances and magnitudes. Results indicated that seismic hazard across these cities is mainly controlled by area sources located along the Dead Sea Transform (DST) fault system. Cities located at short distances from the DST tend to show close deaggregation behavior. Some discrepancies may exist due to the proximity or remoteness of these cities relative to the DST seismic sources and local seismicity. The modal or most probable distance distribution indicated that the distance to the earthquake which contributes most to the hazard at each city is mainly controlled by shaking along faults associated with near seismic area sources. The influence of adjacent seismic sources to the seismic hazard of each city is more evident for the long period spectral acceleration. Distant sources, such as the eastern Mediterranean, Cyprus, Suez and the southern region of the Gulf of Aqaba are relatively low, but can not be neglected due to the intrinsic uncertainties and incomplete seismic data.