GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.2 GNGTS 2024 Fig. 3 – Details of the power spectrum relatve to three moments (of less than 10 minutes to one hour) hours before the Mirabella M=2.1 earthquake. Periodic modulatons of the noise of less than 10 minutes were evidenced between 200 and 800 Hz, on the lef. The entre series of resonances from 19 to 170 Hz appeared during the damping interval at the centre. A detail of one of the three pufs is reported on the right where the sudden increase followed by a gradual fading that lasted two minutes is shown. The right plot also shows an unexpected growth of sound in a well-defned range between 55 and 80 Hz. Acknowledgements The authors thank the Limadou Scienza + (ASI), FURTHER (MUR) and Pianeta Dinamico (INGV- MUR) Projects for their fnancial support. References Cianchini G., et al.; 2023: A month of VLF detecton at Mefte, Valle D’Ansanto, Italy. 41th GNGTS. February 7-9, Bologna. Fidani C.; 2011: The Central Italy electromagnetc network and the 2009 L’Aquila earthquake: observed electric actvity. Geosciences, 1 (1), 3–25. Fidani C., and Martnelli G.; 2015: A possible explanaton for electric perturbatons recorded by the Italian CIEN statons before the 2012 Emilia earthquakes. Boll. Geofs. Teor. Appl. 56, 211–226. Fidani C., et al.; 2020: Electric and Magnetc Recordings by Chiet CIEN Staton During the Intense 2016–2017 Seismic Swarms in Central Italy. Front. Earth Sci., 8:536332.