Simulation of the strong ground motion for the 20 July 2017 (Mw. 6.6) Bodrum–Kos earthquake

Abstract

A strong earthquake with Mw 6.6 occurred on 20 July, 2017 in Gokova Bay at the southwest part of the Turkey, accompanied by a local tsunami which impacted Bodrum (Turkey) and Kos (Greece). This paper presents simulation of strong ground motions from this earthquake to visualize the extent of spectral acceleration over the region. A stochastic finite fault method based on a dynamic corner frequency is utilized as a simulation tool. For validation of simulation, strong motion recordings from 10 closest stations within 76 km are used. Horizontal to vertical spectral ratio and near surface attenuation parameter (kappa) of shear waves at strong motion recording stations are calculated to account for site effects. The most suitable source parameters; stress drop and pulsing area percentage are found as 2.5 MPa with 30–36% based on the residuals analyses. In general, an acceptable level of consistency is found between observed and simulated ground motions. Simulation is more successful at frequencies of 2 Hz and above. Distribution of spectral accelerations at a larger region is calculated with the best validated model parameters and compared with ground motion prediction equations. In spite of significant scatter of synthetics particularly in the near fault region, at longer epicentral distances the median values of Turkish empirical prediction better approximates the synthetics. The current results and further scenario simulations for the region are believed to complement normal faulting synthetic strong ground motion library of Turkey.