Toker, MustafaYavuz, EvrimBalkan, Emir2025-07-302025-07-3020251383-46491573-157X10.1007/s10950-025-10314-y2-s2.0-105011078953https://doi.org/10.1007/s10950-025-10314-yhttps://hdl.handle.net/20.500.14720/28079Understanding clustered earthquake sequences is essential for seismic hazard assessment, as it involves constraining faulting styles and nodal planes of potential ruptures. This study investigates the nature of a dense earthquake sequence (similar to 3000 events) initiated on January 27, 2025, in the Santorini-Amorgos region of the Southern Aegean Sea (SAS), a tectonically active Volcanic Island Arc (VIA). We analyzed 23 shallow crustal earthquakes (Mw >= 4.5, depth <= 10 km) that occurred between February 2-9, 2025, using full-waveform, low-frequency Centroid Moment Tensor (CMT) inversion from regional seismograms. The inversion was complemented by high-resolution Bouguer gravity anomaly data derived from the EIGEN-6C4 satellite gravity model to assess subsurface density variations. The focal mechanisms consistently indicate NE-SW striking, high-angle (>= 45 degrees) normal faults with NW- and SE-dipping planes and centroid depths <= 10 km. Integration of CMT results with gravity anomalies (90-100 mgal) suggests a migrating zone of shallower extensional magmatism (SEM) driving the sequence. These findings reveal a Precursory Seismic Cluster (PSC) and provide new constraints on the seismotectonic and magmatic processes shaping seismic hazard in the region.eninfo:eu-repo/semantics/closedAccessBouguer-Gravity AnomalyClustered Earthquake SequenceExtensional MagmatismFocal MechanismsMoment Tensor SolutionPrecursory Seismic ClusterSantorini-Amorgos IslandsArticleQ3Q2WOS:001531945100001