Determination of buried active faults and earthquake potential for Izmir and its surroundings (western Turkey) using aeromagnetic anomalies and seismological data

Abstract

The paper aims to delineate buried faults in Izmir city and its surroundings, western Turkey using aeromagnetic and seismological data. In this context, the geophysical data processing techniques including reduced‑to‑pole transform (RTP), power spectrum analysis, high-pass filter and second vertical derivative method (SVD) have been applied to the total field aeromagnetic data of the study area. First, to remove the undesirable effects caused by the dipolar nature of the Earth field, RTP transform has been applied to those data. Second, the average depths of the regional and residual sources in the region have been calculated as 16.84 km and 3.75 km, respectively using power spectrum analysis. After, to emphasize the effects of the residual anomalies, the high-pass filter has been applied to the RTP data. Finally, the second vertical derivative method (SVD) has applied to the filtered data for delineating the uncovering buried faults and their lineaments in the eastern part of the Aegean extension. The results from those methods show five major fault zones that could cause devastating earthquakes in the area. Especially, the study reveals for the first time that one of these faults which lies from Doganbey to the city center of Izmir in the literature actually reaches out to Manisa city in the NE direction. As a result, these lineaments can be evaluated as traces of buried faults could be an important clue in predicting earthquake potential.

A comparison of seismicity map and the heat flow map shows that the region (between Cesme and Seferihisar) represented with a low b‑value has a high potential earthquake. The spatial distribution of the earthquakes, b‑values and heat flow values in the depths may be related to the existence thin lithospheric mantle. Furthermore, the region represented by strong aeromagnetic anomalies may be considered to be magmatic material arising from the magma filling inside the strike-slip faults. The fault structure observed on the SVD map are also important for the geothermal energy potential of the region as well.