Abstract <p>The analysis of the instrumental observations showed that M4.2 earthquake, that occurred on January 12, 2025 in the Black Sea, was accompanied by well-recorded acoustic effects and variations in electric and magnetic fields recorded at a considerable distance from the seismic event. An ionospheric effect of the earthquake has been established in the form of variations in the critical frequency <i>F</i>2 layer of the ionosphere (<i>f</i>₀<i>F</i>2), according to the data of the Nicosia ground-based sounding station located at a distance of 1113 km from the epicenter of the earthquake.</p>