Source Characteristics of the 27 October 2025 Mw 6.0 Sındırgı-Balıkesir Earthquake Sequence in Western Türkiye

Türkiye is one of the most seismically active regions due to the complex tectonic collisions relative to the Eurasian, African, and Arabian plates in the Eastern Mediterranean region. These tectonic motions have formed two major strike-slip structures: the right-lateral North Anatolian Fault Zone (NAFZ) and the left-lateral East Anatolian Fault Zone (EAFZ). The province of Sındırgı-Balıkesir is located in the southern Marmara region at central-western Türkiye. It is positioned near the southern branches of the NAFZ and the Aegean graben system, where extensional forces in Western Anatolia are observed. In this region, the active faults generally exhibit NE-SW and NW-SE orientations. On October 27, 2025, a magnitude, M_w 6.0 earthquake occurred in Sındırgı-Aktaş near Balıkesir. Understanding the source characteristics of this event is crucial for defining the local fault mechanisms and tectonics, improving seismic hazard and risk assessments, and performing more accurate ground motion analyses in this region. This study aims to resolve the source parameters and rupture characteristics of this earthquake. The seismological waveform data retrieved from the national networks. operated by Disaster and Emergency Management Authority (AFAD) and Kandilli Observatory and Earthquake Research Institute (KOERI). The earthquake source parameters were estimated using the ISOLA software package. To achieve high precision in estimating the seismic moment and focal mechanism, both point-source and potentially multiple-source inversions are performed. This comparison aims to better characterize the fault behaviour within the Sındırgı segment with respect to previously published PDE reports in the region.