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The very large area of EQ epicenters that contributed to the correlations in Figure 2 is delimited by yellow lines, EQ positions are reported by red dots, and cyan contours delimitate the region where the NOAA satellite detected EBs correlated with EQs.
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A correlation between low L-shell 30–100 keV electrons precipitating into the atmosphere and M ≥ 6 earthquakes in West Pacific was presented in past works where ionospheric events anticipated earthquakes by 1.5–3.5 h. This was a statistical result obtained from the Medium Energy Protons Electrons Detector on board the NOAA-15 satellite, which was a...
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... these randomized cases, the previously obtained correlation peaks completely disappeared. The maximum number of 45 correlation events was found for the greatest time bin of 6 h, which corresponded to 45 EQs identified in the map in Figure 5. The geographical region where EQs correlated with NOAA-15 EBs is delimited by −40° to 30° in latitude and by 245° to 300° in longitude, the yellow line in Figure 5, so included are regions with strong seismic activity, such as Mexico, Caribbean Sea, Guatemala, Honduras, Nicaragua, Costa Rica, Panama, Columbia, Ecuador, Perú, Bolivia, Chile, and a large part of Southeastern Pacific. ...
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... maximum number of 45 correlation events was found for the greatest time bin of 6 h, which corresponded to 45 EQs identified in the map in Figure 5. The geographical region where EQs correlated with NOAA-15 EBs is delimited by −40° to 30° in latitude and by 245° to 300° in longitude, the yellow line in Figure 5, so included are regions with strong seismic activity, such as Mexico, Caribbean Sea, Guatemala, Honduras, Nicaragua, Costa Rica, Panama, Columbia, Ecuador, Perú, Bolivia, Chile, and a large part of Southeastern Pacific. EQ epicenters are indicated by red dots in Figure 5, about half of which are located offshore. ...
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... geographical region where EQs correlated with NOAA-15 EBs is delimited by −40° to 30° in latitude and by 245° to 300° in longitude, the yellow line in Figure 5, so included are regions with strong seismic activity, such as Mexico, Caribbean Sea, Guatemala, Honduras, Nicaragua, Costa Rica, Panama, Columbia, Ecuador, Perú, Bolivia, Chile, and a large part of Southeastern Pacific. EQ epicenters are indicated by red dots in Figure 5, about half of which are located offshore. Note that the total number of mainshocks that occurred during 16.5 years in Figure 5 yellow square was 199, they were about 1/3 of the mainshocks that stroked West Pacific in the same period. ...
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... epicenters are indicated by red dots in Figure 5, about half of which are located offshore. Note that the total number of mainshocks that occurred during 16.5 years in Figure 5 yellow square was 199, they were about 1/3 of the mainshocks that stroked West Pacific in the same period. However, the 45 East Pacific mainshocks of the peak correlation are near the 44 EQs of the West Pacific correlation peak, being the East Pacific correlation bin 3 times the West Pacific correlation bin. ...
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... time distribution of the 45 considered EQs from July 1998 to December 2014 is shown in Figure 6, with their relative magnitudes. Concerning EB detection positions, the geographical region is delimited at −35° and 20° in latitude, and at 205° and 295° in longitude, divided into two inclined belts indicated by cyan contours in Figure 5 whose inclinations are due to the asymmetry of the geomagnetic field. Finally, electron mirror points of detected EBs over the EQ epicenters are plotted in Figure 7, ranging from minimum altitudes between 100 km and 700 km. ...
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We investigate the occurrence of ionospheric irregularities in Nigeria during 2014, using the Global Navigation Satellite System (GNSS) total electron content (TEC) rate of change index (ROTI). We categorized days with |Dst| < 30 nT as quiet days and days with |Dst| ≥ 50 nT as disturbed days, during both the daytime and nighttime periods. Our resul...
Citations
... The anomalous emission and depression in Ultra Low Frequency (ULF) signal near the EQ epicenter can be treated as direct evidence of preseismic impression [Schekotov et al., 2006;Hayakawa et al., 2019Hayakawa et al., , 2023. This emission can be directly linked with magnetospheric variabilities by the concept of energetic particle burst in the radiation belt [Anagnostopoulos et al., 2012;Fidani et al., 2008;Fidani et al., 2021;Fidani et al., 2022;Chowdhury et al., 2022;Battiston et al., 2013]. ...
It is well established that pre-and co-seismic irregularities in the earth's atmosphere highly depend on a set of parameters. According to the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) mechanism, these parameters are associated with various channels (thermal, chemical, acoustic, electromagnetic, etc.) through which an earthquake (EQ) preparation process can have its anomalous phenomena. In this research, we perform a multi-parametric observation using various channels during a strong EQ (M = 6.0) on September 27, 2021, on Crete Island in Greece. We investigate the acoustic and electromagnetic channel using ground and satellite-based observation. We present the Atmospheric Gravity Wave (AGW) in the acoustic channel using the temperature profile computed from the SABER/TIMED instrument. In the electromagnetic channel, ionospheric Total Electron Content (TEC) is recorded by the GNSS-IGS station DYNG in Greece. This TEC information is also used in the acoustic channel anomaly by computing the wave-like structures in the small-scale fluctuation of the TEC profile. We compute energetic (30 to 100 keV) electron precipitation in the inner radiation belt from the NOAA satellite. We also investigate the outcomes of the SWARM satellite to compute the magnetic field and electron density profile. All the parameters show significant seismogenic anomalies (mostly enhancement) before the EQ. To understand each parameter's temporal and spatial sensitivity, we present a comparison using the anomalies in each parameter.
... This question would be addressed for electron losses from the inner VAB, and always during geomagnetically quiet days, to justify a correlation survey between two phenomena where one of them occurs more frequently. This is the case of the correlation between strong EQs and electron bursts where the electron detections occur in nearly all the considered days and their frequency is greater than that of seismic events [42]. Moreover, the area where PELs are detected, which is the same as that for the electron bursts correlated to the western (and eastern) strong seismic events due to the previously found correlation results, should be considered in addressing the request above. ...
On 4 March 2021, a devastating M8.1 earthquake struck the Kermadec Islands of New Zealand. Given the tremendous energy released during the event, we sought to investigate the event's potential impact on the ionosphere and the inner Van Allen Belt using data from the high-energy electron detectors on board the NOAA-18 satellite. The survey was also extended to the strongest shallow M6.5+ earthquakes occurring between 150° and 190° in longitude, and between −5° and −35° in latitude over the previous ten years. In nearly all cases, evident electron fluxes entering the loss cone were observed. To explore the possibility of a connection between ionospheric signals and tectonic events in this intensely active region, we analyzed electron losses from the inner Van Allen Belt, taking into account latitude, longitude, day/night times, and proximity to the South Atlantic Anomaly. Compared to previous studies, here only the most significant loss phenomena persistent in the ionosphere were considered. Particular interest was reserved for the intense electron loss events that had a duration spanning from a few to several minutes and occurred several hours before and after strong seismic events. Thereafter, time series of electron counting rates and strong Southern Pacific earthquakes were transformed into binary series, and the series multiplication was investigated. The results suggest four peaks of association, including a first couple between electron perturbations detected for ascending semi-orbits and seismic events and a second one between electron perturbations detected in the southern ionosphere and seismic events. They both anticipated the occurrence of earthquakes, occurring around 4 h before them. Other couples were observed between electron perturbations detected for descending semi-orbits and seismic events and between electron perturbations detected in the northern ionosphere and seismic events. They both occurred around 3 h after the occurrence of earthquakes. The case of perturbations anticipating seismic events has the intriguing properties of sustaining the hypothesis that a physical interaction occurred around 6 h before seismic events as in the West Pacific case. A physical model of electrons detected far several thousands of km from the earthquake epicenters was also presented. However, a simulation of random seismic events suggested that the null hypothesis cannot be fully rejected for these associations, prompting many more analyses and case studies.
... Moreover, the association between electron losses and strong EQs was investigated by means of the McIlwain or L-shell parameter in the range of the inner belts from 1.1 to 1.4 (Aleksandrin et al., 2003;Sgrigna et al., 2005). Data belonging to the NOAA's Polar Orbiting Environmental Satellites (NOAA-POES) confirmed a statistical correlation between high energy precipitating electrons and West Pacific strong EQs always for low L-shell electrons Battiston and Vitale, 2013;Fidani, 2015;Fidani, 2018;Fidani, 2020;Fidani, 2021;Fidani, 2022). For both case studies analysed-Kermadec Islands EQ and HTHH eruption-the corresponding L-shell parameter estimated through Shepherd (2014) algorithm is L~1.1, which falls within the above mentioned range. ...
The Tonga-Kermadec subduction zone represents one of the most active areas from both seismic and volcanic points of view. Recently, two planetary-scale geophysical events took place there: the 2019 M7.2 earthquake (EQ) with the epicentre in Kermadec Islands (New Zealand) and the astonishing 2022 eruption of Hunga Tonga-Hunga Ha’apai (HTHH) volcano. Based on the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) models, we analysed the three geolayers with a multi-parametric approach to detect any effect on the occasion of the two events, through a comparison aimed at identifying the physics processes that interested phenomena of different nature but in the same tectonic context. For the lithosphere, we conducted a seismic analysis of the sequence culminating with the main shock in Kermadec Islands and the sequence of EQs preceding the HTHH volcanic eruption, in both cases considering the magnitude attributed to the released energy in the lithosphere within the respective Dobrovolsky area. Moving to the above atmosphere, the attention was focused on the parameters—gases, temperature, pressure—possibly influenced by the preparation or the occurrence of the events. Finally, the ionosphere was examined by means of ground and satellite observations, including also magnetic and electric field, finding some interesting anomalous signals in both case studies, in a wide range of temporal and spatial scales. The joint study of the effects seen before, during and after the two events enabled us to clarify the LAIC in this complex context. The observed similarities in the effects of the two geophysical events can be explained by their slightly different manifestations of releasing substantial energy resulting from a shared geodynamic origin. This origin arises from the thermodynamic interplay between a rigid lithosphere and a softer asthenosphere within the Kermadec-Tonga subduction zone, which forms the underlying tectonic context.
A new correlation between strong earthquakes (EQs) and high-energy electron bursts (EBs) has been recently presented (Fidani, 2022). The peak of correlation appeared when considering shallow EQs with hypocentre depth lower than 200 km, located in a large portion of the Earth’s crust in the Eastern Pacific, with a minimum magnitude of 6. It evidenced that the 30-100 keV electron detections by the NOAA-15 satellite anticipate the EQ events around 56.5 h (see Figure 1). The Correlation Event (CE) histogram in Figure 1 was created to maximize the correlation peak, which was obtained by choosing the bins shifted by +0.3 h from 0. It caused correlation values at larger shifts to be lower than all other values. In fact, at these shifts, only a fraction of the 4 h bin is included, so containing less CE.This result to be used for EQ forecasting also required an unambiguous definition of EBs to verify a precursor phenomenology (Wyss, 1997), which was obtained considering EBs with L-shell in a restricted interval as shown in past works (Fidani, 2021; Fidani et al., 2022).
Understanding the process of earthquake preparation is of utmost importance in mitigating the potential damage caused by seismic events. That is why the study of seismic precursors is fundamental. However, the community studying non-seismic precursors relies on measurements, methods, and theories that lack a causal relationship with the earthquakes they claim to predict, generating skepticism among classical seismologists. Nonetheless, in recent years, a group has emerged that seeks to bridge the gap between these communities by applying fundamental laws of physics, such as the application of the second law of thermodynamics in multiscale systems. These systems, characterized by describing irreversible processes, are described by a global parameter called thermodynamic fractal dimension, denoted as D. A decrease in D indicates that the system starts seeking to release excess energy on a macroscopic scale, increasing entropy. It has been found that the decrease in D prior to major earthquakes is related to the increase in the size of microcracks and the emission of electromagnetic signals in localized zones, as well as the decrease in the ratio of large to small earthquakes known as the b-value. However, it is still necessary to elucidate how D, which is also associated with the roughness of surfaces, relates to other rupture parameters such as residual energy, magnitude, or fracture energy. Hence, this work establishes analytical relationships among them. Particularly, it is found that larger magnitude earthquakes with higher residual energy are associated with smoother faults. This indicates that the pre-seismic processes, which give rise to both seismic and non-seismic precursor signals, must also be accompanied by changes in the geometric properties of faults. Therefore, it can be concluded that all types of precursors (seismic or non-seismic), changes in fault smoothness, and the occurrence of earthquakes are different manifestations of the same multiscale dissipative system.
