[M-IS04] Interdisciplinary studies on pre-earthquake processes

[MIS04-04] Resonant signals before the 2021 M6 Luxian Earthquake

*Chieh-Hung Chen¹、Yang-Yi Sun¹、Kai Lin¹ (1.China University of Geosciences, Wuhan, Hubei, China)

キーワード：MVP-LAI system, LAI coupling, Double resonance

An instrumental system was established in southwest China (Leshan; LESH) for monitoring vibrations and perturbations in the lithosphere, atmosphere, and ionosphere (MVP-LAI) in 2021. At the current stage, the system comprises 15 different instruments routinely monitoring 15 distinct geophysical parameters in LAI. Two ground-based GNSS receivers were installed in the substations for receiving the electromagnetic signals transmitted from the BeiDou navigation System (BDS) geostationary satellites that advances in monitoring changes in the total electron content (TEC) at the ionospheric pierce right over the MVP-LAI system. Meanwhile, the substations are located ~260 km away from the MVP-LAI system that can also eliminate potential shaking effects on a study of TEC perturbations over the MVP-LAI system. An earthquake with the magnitude of 6 occurred in the China on 16 September 2021. A distance between the instrumental array and the earthquake is ~146 km that raises our attention to investigate the pre-earthquake anomalous phenomena. We examine the ground vibrations, air pressure, and TEC data from the MVP-LAI system and the substations. A stacking process is further utilized to enhance signal to noise ratios of those data. The enhancements can be found at a fundamental mode of~ 3.4 mHz and its multiples from those data in the frequency domain approximately 1.5 months before the earthquake. The observation results suggest that the resonance waves reside in an area around the earthquake. The ground vibrations would trigger the atmospheric resonance that infers the existence of the double resonance before the earthquake. The double resonance would dominate changes in numerous geophysical parameters in the seismo-LAI coupling.