De Caro, Mariagrazia

On 6 February 2023, Turkey experienced its most powerful earthquake in over 80 years, with a moment magnitude (Mw) of 7.7. This was then followed by a second earthquake of Mw 7.6 just nine hours later. According to the lithosphere–atmosphere–ionosphere coupling (LAIC) models, such a significant seismic activity is expected to cause anomalies across various observables, from the Earth’s surface to the ionosphere. This multidisciplinary study investigates the preparatory phase of these two major earthquakes by identifying potential precursors across the lithosphere, atmosphere, and ionosphere. Our comprehensive analysis successfully identified and collected various anomalies, revealing that their cumulative occurrence follows an accelerating trend, either exponential or power-law. Most anomalies appeared to progress from the lithosphere upward through the atmosphere to the ionosphere, suggesting a sequential chain of processes across these geospheres. Notably, some anomalies deviated from this overall trend, manifesting as oscillating variations. We propose that these anomalies support a two-way coupling model preceding major earthquakes, highlighting the potential role of fluid chemistry in facilitating these processes.

This paper presents an analysis of anomalies detected during the preparatory phase of the 9 November 2022 ML = 5.7 earthquake, occurring approximately 30 km off the coast of the Marche region in the Adriatic Sea (Italy). It was the largest earthquake in Italy in the last 5 years. According to lithosphere–atmosphere–ionosphere coupling (LAIC) models, such earthquake could induce anomalies in various observable variables, from the Earth’s surface to the ionosphere. Therefore, a multiparametric and multilayer approach based on ground and satellite data collected in each geolayer was adopted. This included the revised accelerated moment release method, the identification of anomalies in atmospheric parameters, such as Skin Temperature and Outgoing Longwave Radiation, and ionospheric signals, such as Es and F2 layer parameters from ionosonde measurements, magnetic field from Swarm satellites, and energetic electron precipitations from NOAA satellites. Several anomalies were detected in the days preceding the earthquake, revealing that their cumulative occurrence follows an exponential trend from the ground, progressing towards the upper atmosphere and the ionosphere. This progression of anomalies through different geolayers cannot simply be attributed to chance and is likely associated with the preparation phase of this earthquake, supporting the LAIC approach.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 settembre al 31 dicembre 2022 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (M≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag-6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 gennaio al 30 aprile 2023 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (M≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

The Algerian offshore earthquake of 18 March 2021, Mw 6.0, was felt by people in various Italian regions, also at large epicentral distance. This unusual human perception far from the source prompted us to analyze the waveforms recorded by land seismic stations installed along the Iberian, French, and Italian coasts. On some seismograms of the selected network, prominent T phases are detected. T waves can travel in the SOund Fixing And Ranging (SOFAR) channel over great distances (thousands of kilometers) with little loss in signal strength and be recorded by near‐coastal seismometers after the P (primary) and S (secondary) phases (hence T or tertiary phases). To explain the subjective perception of ground shaking with quantities that are measured on the seismogram, we estimated the empirical macroseismic intensities for both body and T phases and we calculated the body‐wave seismic attenuation. The P‐wave anelastic attenuation analysis shows two main wave propagation patterns that reflect lithosphere heterogeneity of the Algerian, Liguro‐Provençal, and Tyrrhenian basins. We find that in some cases, in particular along the Italian and French coasts, the largest ground shaking is caused by the T phase. Our observations confirm that the central‐western Mediterranean Sea is a favorable site for T‐wave propagation and suggest that the T phases should be taken into account in ground‐shaking hazard assessment for the central‐western Mediterranean.

The coupling processes among the lithosphere, atmosphere, and ionosphere (LAI) during the earthquake preparation phase are still an open scientific debate. Comprehensive LAI coupling effects around the 2022 Ms6.8 Luding earthquake in China are investigated with a multi-parameter and multi-layer approach, including the b-value, revised accelerated moment release, Earth resistivity, ELF magnetic field emissions, atmospheric electric field, surface temperature, foF2 from ionosonde, GNSS TEC, Ne and magnetic field from CSES and Swarm satellites, and energetic electrons from CSES and NOAA satellites. It is found that the anomalies start from the lithospheric parameters as Earth resistivity and b-values 1–2 years before to reflect the local stress loading in the seismic region, then the ionospheric and atmospheric disturbances occur and accelerate −50 days before and −15 days before, and finally the electrons precipitate a few days before. The simultaneous perturbations in LAI illustrate the thermodynamic coupling channel, such as on 24 August, −12 days before. Meanwhile, the abundant developed ionospheric anomalies without atmospheric disturbances demonstrate the electromagnetic coupling way from the lithosphere to the ionosphere directly. Finally, the results demonstrate a two-way model of LAIC: one way is characterized by a slow chain of processes, of thermodynamic nature, starting from the ground and proceeding to the above atmosphere and ionosphere, showing an exponential trend in the cumulative number of anomalies; the second way is characterized by oscillating electromagnetic coupling between the lithosphere and ionosphere, showing intermittent fluctuations in the corresponding cumulative number of anomalies.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 maggio al 31 agosto 2022 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5), e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 gennaio al 30 aprile 2022 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5), e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 settembre al 31 dicembre 2021 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 maggio al 31 agosto 2021 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag-6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.