A New Ground Motion Model for Iran

Date: 4/24/2019

Time: 06:00 PM

Room: Grand Ballroom

Ground-motion models (GMMs) are the key element of a probabilistic seismic hazard analysis (PSHA), in which their validity is dependent on the sufficiency of the data. The quality and quantity of the recorded data have increased over the last couple of decades; as the result, researchers are trying to develop models that are based on more recent and more accurate data.

In this study, we develop a partial non-ergodic horizontal empirical GMM for Iran considering five major seismotectonic provinces. This study uses a newly developed database of strong ground motion for Iran. We used moment magnitudes <b> M </b> ranging from 4.8 to 7.5 and shortest distances from site to a rupture surface, <i> R</i> _rup, less than 400 km for shallow earthquakes with focal depths less than 35 km. We used a mixed-effects regression algorithm to determine inter-event and intra-event residuals. The functional form used includes 14 coefficients which we obtain by prescribing the event- and site-specific uncertainties associated with the magnitude and the average shear-wave velocity.

The GMPEs are derived for the peak ground acceleration (PGA) and 5%-damped pseudo-acceleration response-spectral ordinates (PSA) at periods ranging from 0.01 to 4 s. The proposed GMM is developed for a reference site defined as rock with <i> V</i> _S30 = 760 m/s. The database used also includes ground motion information and source characterization and parameters.

The proposed GMM for Iran includes a nonlinear site-response term in the functional form. We do show that it is important to consider a nonlinear term in the functional form. Finally, we compare our GMM with recent published GMMs for Iran.

Presenting Author: Zoya Farajpour

Authors