We present a ground‐motion prediction equation (GMPE) for Turkey and Iran to investigate the possible regional effects on ground‐motion amplitudes in shallow active crustal earthquakes. The proposed GMPE is developed from a subset of the recently compiled strong‐motion database of the Earthquake Model of the Middle East Region project (see Data and Resources). A total of 670 Turkish and 528 Iranian accelerograms with depths down to 35 km are used to estimate peak ground acceleration, peak ground velocity, and 5% damped elastic pseudospectral acceleration ordinates of 0.01 s≤T≤4 s. The moment magnitude range of the model is 4≤Mw≤8, and the maximum Joyner–Boore distance is RJB=200 km. The functional form considers three major fault mechanisms (strike slip, normal, and reverse). The nonlinear soil behavior is a function of VS30 (average shear‐wave velocity in the upper 30 m of soil profile). Our observations from empirical and estimated ground‐motion trends advocate regional differences in the territories covered by Iran and Turkey that originate from the differences in Q factors, kappa, and near‐surface velocity profiles. These factors eventually affect the magnitude‐ and distance‐dependent scaling of spectral amplitudes in Iran and Turkey. In essence, the ground‐motion amplitudes of these two neighboring countries would draw patterns different than the ground‐motion estimates of GMPEs developed from the strong‐motion databases of shallow active crustal earthquakes from multiple countries.
Online Material: MATLAB code and regression coefficients for computing the response spectrum and distance scaling.