Akademik Veri Yönetim Sistemi
Advances in Space Research, 2026 (SCI-Expanded, Scopus)
Electromagnetic anomalies in the Earth’s magnetic field have long been investigated as potential short- and medium-term precursors to earthquakes, reflecting processes such as stress accumulation, microfracturing, and charge migration within the crust. Documenting these signals is essential for understanding lithosphere–atmosphere–ionosphere coupling mechanisms and for assessing their potential role in earthquake forecasting. This study examines possible geomagnetic anomalies before, during, and after the Mw 6.2 earthquake that struck the Marmara Sea in northwestern Türkiye on April 23, 2025. One-minute geomagnetic field data from three ground-based observatories—IZN (proximal to the epicentre) and PEG and PAG (more distant reference stations)—were analyzed. The rate of change of the geomagnetic field (ROG) and the corresponding ROG Index (rogi), reflecting the relative intensity of these variations, were calculated. To suppress external influences from space weather, data were filtered using X-ray flux, Dst, and Kp indices. Two short-duration, high-amplitude magnetic disturbances were detected exclusively at the IZN station—approximately five days and five minutes before the mainshock—while no such anomalies were observed at the control stations. On April 23, the geomagnetic environment remained quiet, with X-ray flux limited to the C-class, Kp values below 3, and Dst not dropping below –50 nT. These conditions support a local, seismogenic origin for the anomalies. Notably, the sharp pre-seismic increase in rogi suggests a seismomagnetic response, potentially driven by piezoelectric, electrokinetic, or thermoionic mechanisms. These findings provide novel evidence that electromagnetic precursors can be detected even for moderate-magnitude earthquakes and represent the first high-resolution ground-based observations of geomagnetic field disturbances associated with the April 23 Marmara Sea event.