Seismotectonic Investigation of Biga Peninsula in SW Marmara Region Using Steerable Filter Technique, Potential Field Data and Recent Seismicity

Abstract

We examine seismotectonic setting of Biga Peninsula in western Anatolia (Canakkale region) using the steerable filter technique and recent seismicity. One of the most important issues in geophysics is to observe borders or margins of tectonic/geologic discontinues. For this purpose, we apply this filter technique to gravity anomaly map of Biga Peninsula. We observe undetected/buried faults in Biga Peninsula using the steerable technique where they have never been seen in the geological maps before. These buried faults comply with recent seismicity for this region. Focal mechanisms of past earthquakes (M ae 3.5) are in good agreement with fault orientations. This observation shows that we have to take into account these fault locations and consider for preparing future seismic hazard maps. The geometry of fault segments reveals mostly strike-slip faulting regime with NE-SW trending direction of T-axis in the entire study region. According to high-resolution hypocenter relocation of the Biga earthquake sequences in the observation period between 5 January 2005 and 14 November 2015 extends from N to S direction. The stress tensor inversion results indicate a predominant normal stress regime with a NW-SE oriented maximum horizontal compressive stress (S (H)). According to strong discrepancy of density in the Biga Peninsula is characterized by numerous small segmented secondary faults. These buried or undetected fault locations indicate that these segments are large enough to increase earthquake stress failure towards NW-SE and N-S directions, respectively. Seismotectonic setting of Biga Peninsula is divided into sub-regions by NE-SW trending secondary faults with normal and major strike-slip components. This output is verified by steerable filter and local/regional seismotectonic analysis. We propose a new seismotectonic model for Biga Peninsula and update the orientation of active fault segments. According to our model, North Anatolian Fault Zone cross-cuts the southern Marmara basins as a narrow fault segment and continues towards Aegean Sea.