On the Correlation of Seismic Noise in Izmir City, Aegean Region of Turkey: Preliminary Results

Seismic risk in the Eastern part of Turkey is high due to active tectonics in the region. Recently, a new seismic network was installed in Izmir region. Because the objective was to analyze seismic response, not all stations were installed on firm rock. Rather, the different geologic formation at the surface was sampled by the 16 sites. The stations are high quality, digital accelerographs by Guralp, writing continuously. Preliminary analysis of earthquake data recorded to date has been presented in Gok (2011). The results gave some estimate of transfer functions for the different sites. However, no information is available on the subsoil structure. We need to have the structure to compute response and compare with observed seismic response. For this reason, we have taken advantage of the continuous recording at the array. Seismic noise is analyzed in this paper using correlation to estimate Green's function between station pairs. The preliminary results are encouraging. We are able to estimate group velocities between stations, although signal-to-noise ratios are small and the frequency band of the pulses is restricted. In spite of this, we present a preliminary map of velocity variation as a function of path for the Izmir gulf region.