Report on a pre-earthquake signal detection by enhanced Eötvös torsion balance

More than 30 minutes before the earthquake event in Florina, Greece at 21:43:47(UTC) on 9th January 2022 an enhanced Eötvös torsion balance registered unidentified signals in the Jánossy Underground Research Laboratory in Budapest, Hungary. These signals were not visible on the seismograms, although seismic noises are continuously recorded by a side-by-side broadband seismometer. Moreover, seismological stations did not detect anything unusual, they presented a negative confirmation of the events. Our observation suggests that torsion balances might effectively detect precursory earthquake signals from a considerable distance. Such a finding could trigger the development of new observational devices and networks and can provide novel knowledge about the origin and mechanism of earthquake phenomena.