Akademik Veri Yönetim Sistemi
PURE AND APPLIED GEOPHYSICS, cilt.179, sa.2, ss.709-745, 2022 (SCI-Expanded)
This study aims to determine the 1D deep S-wave velocity structure for canakkale Province and the surrounding area (Biga Peninsula, NW Turkey) using the moderate (M >= 4.0) earthquakes from the last decade. A total of 540 velocity seismograms with a high S/N ratio are obtained from 218 three-component acceleration records of the 10 earthquakes (4.0 <= M-w <= 5.3) that occurred in the areas of Ayvacik, Saros, and can between 2010 and 2018. A total of 34 strong ground motion stations operated by AFAD are grouped in 27 azimuthal directions, and fundamental mode surface wave group velocity dispersion curves are obtained using the multiple-filter method. First, the observed dispersion curves are utilized for the inversion application to define the 1D deep Vs model. Then they are compared with the theoretical curves of the tuned 1D deep Vs models with the trial-and-error forward method after inversion. The RMS misfits between observed and calculated surface group velocities decrease from 0.6 to 0.2 on average. The dispersion analyses allow for improved seismic velocities and thicknesses of especially the uppermost 4-5 km. The defined 1D deep Vs model of 202 source-station paths are also inferred to obtain an average pseudo-3D deep Vs model. In addition, the velocity models are verified with 1D numerical ground motion simulations for 0.05-1 Hz, including the characterized source models of the earthquakes and 1D shallow soil amplifications. The simulation results are quantitatively evaluated with goodness-of-fit measures considering different frequency bands. Fairly good agreement for waveform first arrival and spectral amplitude (0.05-1 Hz) is achieved. However, the later wave packages at the sites located on thick sediment basins cannot be modeled because of the reverberations in the sediment overlying the engineering bedrock. The test of the pseudo-3D Vs model using broadband (0.05-10 Hz) simulation of the 2017 Lesvos mainshock (M-w 6.3) also indicates that both the phase arrival times (< 1 Hz) and the amplitude spectral decay in the high-frequency range of 1-7 Hz are well modeled.