مرکز منطقه ای اطلاع رساني علوم و فناوري - GROUND MOTION SIMULATION FOR ISTANBUL WITH A THREE DIMENSIONAL VELOCITY MODEL

Abstract :

In this study strong ground motions in Istanbul due to a Mw7,2 scenario earthquake on Northern Boundary of North Anatolian Fault were simulated. A rupture is anticipated to pass through southwest of the Prince Islands in the Marmara Sea. A three dimensional velocity structure was integrated into a finite difference simulation technique. In order to validate the proposed velocity structure for Istanbul area, synthetic and recorded ground motion recordings were compared. The structure was modified by available shallow velocity profiles, hence low frequency ground motions were calculated. High frequency ground motions were obtained by stochastic techniques. Ground motion simulations for the scenario earthquake were performed by hybrid Green’s functions using three different asperity models. For bileteral rupture propagation (Scenario 1) peak accelerations on the European side were found to be within 5 m/s2, whereas on the Asian side they reached up to 8 m/s2. Due to forward directivity effects, unilateral rupture propagation towards northwest (Scenario 2) increased the peak accelerations and velocities on the European side up to 7 m/s2 and 1,6 m/s, respectively. It was also found that unilateral rupture propagation toward southeast (Scenario 3) causes only localised high accelerations due to the combination of source and local site effects.