Study the Geospace impact and the re-occurrence of pre-earthquake signals in the atmosphere: Preliminary analysis for the 2024 M 7.0 Cape Mendocino, CA and 2025 M 7.1 Southern Tibetan Plateau Earthquakes.

This study explores the processes of generating pre-earthquake abnormalities in the atmosphere/ionosphere associated with significant seismicity. We analyzed two major earthquakes that occurred recently in N. America and Asiа. The M 7.0  of Dec 5, 2024, Offshore Cape Mendocino, California Earthquake is a strike-slip shallow event (10km depth) west of the Mendocino Triple Junction, one of California's most active seismic regions. The M 7.1 of Jan 7, 2025, Southern Tibetan Plateau Earthquake was a typical faulting earthquake, the largest in the area since an M7.1 struck 171 km to the south on 26 April 2015 in Nepal. Оur primary objective is to assess the solar-geophysical conditions preceding both events and, with a thorough validation study of pre-earthquake signals occurrence in the Atmosphere/ionosphere to understand the associated lithosphere-atmosphere coupling phenomena’ similarities and differences.

For the first time, we combine observations from earth and geospace monitoring systems, such as NPOESS, GNSS, CSES1, FORMOSAT-7/COSMIC-2, and NASA assimilation models in such comparison studies. We analyzed: 1/ Cloud features (CF) with NASA EOS MODIS and Thermal Radiation anomalies (TRA) obtained from satellites NPOESS; 2/ Ionospheric plasma observations from China/Italy Seismo-Electromagnetic Satellite (CSES1);3/Electron density variations in the ionosphere via GPS Total Electron Content (GPS/TEC) and FORMOSAT-7/COSMIC-2 and  4/ Atmospheric chemical potential (ACP) obtained from NASA assimilation models. The initial results reveal that the magnetic storms in October – November 2024 could provoke the M7 earthquake in California (December 5, 2024) and the M7.1 earthquake in Tibet (January 7, 2025). Still, additional work is needed to establish the precise connection. The pre-earthquake signatures demonstrate synergetic coordination between the occurrences of CF,  TRA, and ACP anomalies of transient effects in the atmosphere and ionosphere. In the case of the Cape Mendocino, CA earthquake, the pre-earthquake signals occurred slightly later because of the ocean type of event compared to Tibetan signatures, which mimicked the sequence of the 2015 M7.8 Gorkha earthquake (Nepal). The continuous detection of atmospheric signatures over the Southern Tibetan Plateau indicated probably that more aftershocks are likely.  The spatial characteristics of the pre-earthquake anomalies for both events were associated with large areas and scaled with the earthquake preparation zone, as estimated by the Dobrovolsky-Bowman relationship. In general, we discuss the significance of the re-occurrence of pre-earthquake signals during the preparation process.