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Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives
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Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives

A special issue of Geosciences (ISSN 2076-3263). This special issue belongs to the section "Natural Hazards".

Deadline for manuscript submissions: closed (31 March 2024) | Viewed by 21176

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Prof. Dr. Masashi Hayakawa

E-Mail Website
Guest Editor
1. Hayakawa Institute of Seismo Electromagnetics, Co. Ltd. (Hi-SEM), UEC Alliance Center, 1-1-1 Kojima-cho, Chofu 182-0026, Japan
2. Advanced Wireless & Communication Research Center (AWCC), The University of Electro-Communications, 1-5-1, Chofugaoka, Chofu 182-8585, Japan
Interests: space physics (magnetosphere/ionosphere); space plasma physics; plasma waves (wave-particle interactions and wave propagation); planetary magnetospheres; atmospheric electricity; lightning physics; VLF/ELF sferics; schumann resonances; direction finding; seismo-electromagnetics; critical analysis; lithosphere-atmosphere-ionosphere coupling; earthquake prediction; signal processing

Special Issue Information

Dear Colleagues,

Earthquake (EQ) prediction (especially short-term) is one of the most challenging subjects left in the field of geoscience. Over the last three decades, it was found, based on enormous effort by enthusiastic scientists globally, that non-seismic (mainly electromagnetic) precursors do exist before an EQ, which could be a possible candidate of short-term EQ prediction. Even though an EQ is a tectonic phenomenon which is the consequence of pressure accumulation in the fault regions of lithosphere, electromagnetic precursors appear not only in the lithosphere, but also in the atmosphere and ionosphere. Additionally, the most surprising finding was that the upper ionosphere is extremely sensitive to pre-EQ lithospheric seismic activity, and a new concept of lithosphere–atmosphere–ionosphere coupling (LAIC) has appeared, indicating the coupling and feedback of various phenomena in different layers of the Earth. Several hypotheses have been proposed to explain this LAIC process based on ground- and satellite-based measurements as well as theoretical modeling, but, of course, with some arguments against this idea. Enormous progress has been achieved in the field of the LAIC process in recent years with the use of new ideas, new observational findings, and theoretical modeling. Therefore, this Special Issue is intended to collect recent advances in EQ precursor studies and also recent activities for different channels of this LAIC. Additionally, we aim to discuss future perspectives as a further step for the future realization of short-term EQ prediction. This Special Issue aims to collect mainly extensive papers (either reviews or original articles) by active scientists in this particular field, but we also welcome any contributions which will provide readers with new insights into our complicated but very attractive topic of the LAIC process during the preparation phase of EQs.  

Prof. Dr. Masashi Hayakawa
Guest Editor

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Keywords

  • earthquake (EQ) precursors
  • short-term EQ prediction
  • lithosphere–atmosphere–ionosphere coupling (LAIC)
  • multi-parameter observations of seismogenic effects
  • ground- and satellite-based observations
  • theoretical modelling of different channels of LAIC process
  • critical analysis
  • statistical significance of EQ precursors

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Published Papers (12 papers)

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Research

33 pages, 18761 KiB  
Article
Earthquake Precursors: The Physics, Identification, and Application
by Sergey Pulinets and Victor Manuel Velasco Herrera
Geosciences 2024, 14(8), 209; https://doi.org/10.3390/geosciences14080209 - 5 Aug 2024
Viewed by 2002
Abstract
The paper presents the author’s vision of the problem of earthquake hazards from the physical point of view. The first part is concerned with the processes of precursor’s generation. These processes are a part of the complex system of the lithosphere–atmosphere–ionosphere–magnetosphere coupling, which [...] Read more.
The paper presents the author’s vision of the problem of earthquake hazards from the physical point of view. The first part is concerned with the processes of precursor’s generation. These processes are a part of the complex system of the lithosphere–atmosphere–ionosphere–magnetosphere coupling, which is characteristic of many other natural phenomena, where air ionization, atmospheric thermodynamic instability, and the Global Electric Circuit are involved in the processes of the geosphere’s interaction. The second part of the paper is concentrated on the reliable precursor’s identification. The specific features helping to identify precursors are separated into two groups: the absolute signatures such as the precursor’s locality or equatorial anomaly crests generation in conditions of absence of natural east-directed electric field and the conditional signatures due to the physical uniqueness mechanism of their generation, or necessity of the presence of additional precursors as multiple consequences of air ionization demonstrating the precursor’s synergy. The last part of the paper is devoted to the possible practical applications of the described precursors for purposes of the short-term earthquake forecast. A change in the paradigm of the earthquake forecast is proposed. The problem should be placed into the same category as weather forecasting or space weather forecasting. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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27 pages, 1079 KiB  
Article
A PLL-Based Doppler Method Using an SDR-Receiver for Investigation of Seismogenic and Man-Made Disturbances in the Ionosphere
by Nazyf Salikhov, Alexander Shepetov, Galina Pak, Vladimir Saveliev, Serik Nurakynov, Vladimir Ryabov and Valery Zhukov
Geosciences 2024, 14(7), 192; https://doi.org/10.3390/geosciences14070192 - 16 Jul 2024
Viewed by 903
Abstract
The article describes in detail the equipment and method for measuring the Doppler frequency shift (DFS) on an inclined radio path, based on the principle of the phase-locked loop using an SDR receiver for the investigation of seismogenic and man-made disturbances in the [...] Read more.
The article describes in detail the equipment and method for measuring the Doppler frequency shift (DFS) on an inclined radio path, based on the principle of the phase-locked loop using an SDR receiver for the investigation of seismogenic and man-made disturbances in the ionosphere. During the two M7.8 earthquakes in Nepal (25 April 2015) and Turkey (6 February 2023), a Doppler ionosonde detected co-seismic and pre-seismic effects in the ionosphere, the appearances of which are connected with the various propagation mechanisms of seismogenic disturbance from the lithosphere up to the ionosphere. One day before the earthquake in Nepal and 90 min prior to the main shock, an increase in the intensity of Doppler bursts was detected, which reflected the disturbance of the ionosphere. A channel of geophysical interaction in the system of lithosphere–atmosphere–ionosphere coupling was traced based on the comprehensive monitoring of the DFS of the ionospheric signal, as well as of the flux of gamma rays in subsoil layers of rocks and in the ground-level atmosphere. The concept of lithosphere–atmosphere–ionosphere coupling, where the key role is assigned to ionization of the atmospheric boundary layer, was confirmed by a retrospective analysis of the DFS records of an ionospheric signal made during underground nuclear explosions at the Semipalatinsk test site. A simple formula for reconstructing the velocity profile of the acoustic pulse from a Dopplerogram was obtained, which depends on only two parameters, one of which is the dimension of length and the other the dimension of time. The reconstructed profiles of the acoustic pulses from the two underground nuclear explosions, which reached the height of the reflection point of the sounding radio wave, are presented. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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20 pages, 9973 KiB  
Article
The Preparation Phase of the 2022 ML 5.7 Offshore Fano (Italy) Earthquake: A Multiparametric–Multilayer Approach
by Martina Orlando, Angelo De Santis, Mariagrazia De Caro, Loredana Perrone, Saioa A. Campuzano, Gianfranco Cianchini, Alessandro Piscini, Serena D’Arcangelo, Massimo Calcara, Cristiano Fidani, Adriano Nardi, Dario Sabbagh and Maurizio Soldani
Geosciences 2024, 14(7), 191; https://doi.org/10.3390/geosciences14070191 - 16 Jul 2024
Viewed by 903
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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18 pages, 7532 KiB  
Article
On the Impact of Geospace Weather on the Occurrence of M7.8/M7.5 Earthquakes on 6 February 2023 (Turkey), Possibly Associated with the Geomagnetic Storm of 7 November 2022
by Dimitar Ouzounov and Galina Khachikyan
Geosciences 2024, 14(6), 159; https://doi.org/10.3390/geosciences14060159 - 7 Jun 2024
Cited by 4 | Viewed by 1828
Abstract
A joint analysis of solar wind, geomagnetic field, and earthquake catalog data showed that before the catastrophic M = 7.8 and M = 7.5 Kahramanmaras earthquake sequence on 6 February 2023, a closed strong magnetic storm occurred on 7 November 2022, SYM/H = [...] Read more.
A joint analysis of solar wind, geomagnetic field, and earthquake catalog data showed that before the catastrophic M = 7.8 and M = 7.5 Kahramanmaras earthquake sequence on 6 February 2023, a closed strong magnetic storm occurred on 7 November 2022, SYM/H = −117 nT. The storm started at 08:04 UT. At this time, the high-latitudinal part of Turkey’s longitudinal region of future epicenters was located under the polar cusp, where the solar wind plasma would directly access the Earth’s environment. The time delay between storm onset and earthquake occurrence was ~91 days. We analyzed all seven strong (M7+) earthquakes from 1967 to 2020 to verify the initial findings. A similar pattern has been revealed for all events. The time delay between magnetic storm onset and earthquake occurrence varies from days to months. To continue these investigations, a retrospective analysis of seismic and other geophysical parameters just after preceded geomagnetic storms in the epicenter areas is desirable. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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11 pages, 1832 KiB  
Article
Feasibility of Principal Component Analysis for Multi-Class Earthquake Prediction Machine Learning Model Utilizing Geomagnetic Field Data
by Kasyful Qaedi, Mardina Abdullah, Khairul Adib Yusof and Masashi Hayakawa
Geosciences 2024, 14(5), 121; https://doi.org/10.3390/geosciences14050121 - 29 Apr 2024
Cited by 1 | Viewed by 1531
Abstract
Geomagnetic field data have been found to contain earthquake (EQ) precursory signals; however, analyzing this high-resolution, imbalanced data presents challenges when implementing machine learning (ML). This study explored feasibility of principal component analyses (PCA) for reducing the dimensionality of global geomagnetic field data [...] Read more.
Geomagnetic field data have been found to contain earthquake (EQ) precursory signals; however, analyzing this high-resolution, imbalanced data presents challenges when implementing machine learning (ML). This study explored feasibility of principal component analyses (PCA) for reducing the dimensionality of global geomagnetic field data to improve the accuracy of EQ predictive models. Multi-class ML models capable of predicting EQ intensity in terms of the Mercalli Intensity Scale were developed. Ensemble and Support Vector Machine (SVM) models, known for their robustness and capabilities in handling complex relationships, were trained, while a Synthetic Minority Oversampling Technique (SMOTE) was employed to address the imbalanced EQ data. Both models were trained on PCA-extracted features from the balanced dataset, resulting in reasonable model performance. The ensemble model outperformed the SVM model in various aspects, including accuracy (77.50% vs. 75.88%), specificity (96.79% vs. 96.55%), F1-score (77.05% vs. 76.16%), and Matthew Correlation Coefficient (73.88% vs. 73.11%). These findings suggest the potential of a PCA-based ML model for more reliable EQ prediction. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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16 pages, 3471 KiB  
Article
Possible Interrelations of Space Weather and Seismic Activity: An Implication for Earthquake Forecast
by Valery Sorokin and Victor Novikov
Geosciences 2024, 14(5), 116; https://doi.org/10.3390/geosciences14050116 - 25 Apr 2024
Cited by 2 | Viewed by 2494
Abstract
The statistical analysis of the impact of the top 50 X-class solar flares (1997–2024) on global seismic activity as well as on the earthquake preparation zones located in the illuminated part of the globe and in an area of 5000 km around the [...] Read more.
The statistical analysis of the impact of the top 50 X-class solar flares (1997–2024) on global seismic activity as well as on the earthquake preparation zones located in the illuminated part of the globe and in an area of 5000 km around the subsolar point was carried out. It is shown by a method of epoch superposition that for all cases, an increase in seismicity is observed, especially in the region around the subsolar point (up to 33%) during the 10 days after the solar flare in comparison with the preceding 10 days. The case study of the aftershock sequence of a strong Mw = 9.1 earthquake (Sumatra–Andaman Islands, 26 December 2004) after the solar flare of X10.16 class (20 January 2005) demonstrated that the number of aftershocks with a magnitude of Mw ≥ 2.5 increases more than 17 times after the solar flare with a delay of 7–8 days. For the case of the Darfield earthquake (Mw = 7.1, 3 September 2010, New Zealand), it was shown that X-class solar flares and M probably triggered two strong aftershocks (Mw = 6.1 and Mw = 5.9) with the same delay of 6 days on the Port Hills fault, which is the most sensitive to external electromagnetic impact from the point of view of the fault electrical conductivity and orientation. Based on the obtained results, the possible application of natural electromagnetic triggering of earthquakes is discussed for the earthquake forecast using confidently recorded strong external electromagnetic triggering impacts on the specific earthquake preparation zones, as well as ionospheric perturbations due to aerosol emission from the earthquake sources recorded by satellites. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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29 pages, 13747 KiB  
Article
Observation of the Preparation Phase Associated with Mw = 7.2 Haiti Earthquake on 14 August 2021 from a Geophysical Data Point of View
by Dedalo Marchetti
Geosciences 2024, 14(4), 96; https://doi.org/10.3390/geosciences14040096 - 30 Mar 2024
Cited by 1 | Viewed by 1885
Abstract
On 14 August 2021, an earthquake of moment magnitude Mw = 7.2 hit Haiti Island. Unfortunately, it caused several victims and economic damage to the island. While predicting earthquakes is still challenging and has not yet been achieved, studying the preparation phase of [...] Read more.
On 14 August 2021, an earthquake of moment magnitude Mw = 7.2 hit Haiti Island. Unfortunately, it caused several victims and economic damage to the island. While predicting earthquakes is still challenging and has not yet been achieved, studying the preparation phase of such catastrophic events may improve our knowledge and pose the basis for future predictions of earthquakes. In this paper, the six months that preceded the Haiti earthquake are analysed, investigating the lithosphere (by seismic catalogue), atmosphere (by climatological archive) and ionosphere by China Seismo-Electromagnetic Satellite (CSES-01) and Swarm satellites, as well as Total Electron Content (TEC) data. Several anomalies have been extracted from the analysed parameters using different techniques. A comparison, especially between the different layers, could increase or decrease the probability that a specific group of anomalies may be (or not) related to the preparation phase of the Haiti 2021 earthquake. In particular, two possible coupling processes have been revealed as part of the earthquake preparation phase. The first one was only between the lithosphere and the atmosphere about 130 days before the mainshock. The second one was about two months before the seismic event. It is exciting to underline that all the geo-layers show anomalies at that time: seismic accumulation of stress showed an increase of its slope, several atmospheric quantities underline abnormal atmospheric conditions, and CSES-01 Ne depicted two consecutive days of ionospheric electron density. This suggested a possible coupling of lithosphere–atmosphere and ionosphere as a sign of the increased stress, i.e., the impending earthquake. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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15 pages, 2454 KiB  
Article
Thermal Anomalies Observed during the Crete Earthquake on 27 September 2021
by Soujan Ghosh, Sudipta Sasmal, Sovan K. Maity, Stelios M. Potirakis and Masashi Hayakawa
Geosciences 2024, 14(3), 73; https://doi.org/10.3390/geosciences14030073 - 9 Mar 2024
Cited by 3 | Viewed by 1721
Abstract
This study examines the response of the thermal channel within the Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) mechanism during the notable earthquake in Crete, Greece, on 27 September 2021. We analyze spatio-temporal profiles of Surface Latent Heat Flux (SLHF), Outgoing Longwave Radiation (OLR), and Atmospheric Chemical [...] Read more.
This study examines the response of the thermal channel within the Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) mechanism during the notable earthquake in Crete, Greece, on 27 September 2021. We analyze spatio-temporal profiles of Surface Latent Heat Flux (SLHF), Outgoing Longwave Radiation (OLR), and Atmospheric Chemical Potential (ACP) using reanalysis data from the National Oceanic and Atmospheric Administration (NOAA) satellite. Anomalies in these parameters are computed by removing the background profile for a non-seismic condition. Our findings reveal a substantial anomalous increase in these parameters near the earthquake’s epicenter 3 to 7 days before the main shock. The implications of these observations contribute to a deeper understanding of the LAIC mechanism’s thermal channel in seismic events. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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10 pages, 2594 KiB  
Article
Global Rayleigh Wave Attenuation and Group Velocity from International Seismological Centre Data
by Thomas Martin Hearn
Geosciences 2024, 14(2), 50; https://doi.org/10.3390/geosciences14020050 - 10 Feb 2024
Viewed by 1772
Abstract
This paper presents a study of global Rayleigh wave attenuation and group velocity at a period of around 20 s using data from the International Seismological Centre (ISC) bulletin. Rayleigh waves at this period are sensitive to the crustal structure beneath continents and [...] Read more.
This paper presents a study of global Rayleigh wave attenuation and group velocity at a period of around 20 s using data from the International Seismological Centre (ISC) bulletin. Rayleigh waves at this period are sensitive to the crustal structure beneath continents and the uppermost mantle beneath oceans. Tomographic imaging reveals strong continental-ocean contrasts due to this. Oceanic group velocities are high but vary with seafloor depth, while oceanic attenuation shows mid-ocean ridges. Subduction zone regions display high attenuation but little velocity reduction, indicating scattering attenuation. Low attenuation regions are associated with the Earth’s major cratonic regions, but there are no associated velocity changes. This implies that intrinsic attenuation is low and scattering dominates. Cratonic crustal scatterers have been annealed. A new surface wave magnitude scale is constructed that is valid from near-source to near-antipode distances. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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16 pages, 14268 KiB  
Article
Topside Ionospheric Structures Determined via Automatically Detected DEMETER Ion Perturbations during a Geomagnetically Quiet Period
by Mei Li, Hongzhu Yan and Yongxian Zhang
Geosciences 2024, 14(2), 33; https://doi.org/10.3390/geosciences14020033 - 28 Jan 2024
Cited by 1 | Viewed by 1429
Abstract
In this study, 117,718 ionospheric perturbations, with a space size (t) of 20–300 s but no amplitude (A) limit, were automatically globally searched via software utilizing ion density data measured by the DEMETER satellite for over 6 years. The [...] Read more.
In this study, 117,718 ionospheric perturbations, with a space size (t) of 20–300 s but no amplitude (A) limit, were automatically globally searched via software utilizing ion density data measured by the DEMETER satellite for over 6 years. The influence of geomagnetic storms on the ionosphere was first examined. The results demonstrated that storms can globally enhance positive ionospheric irregularities but rarely induce plasma variations of more than 100%. The probability of PERs with a space size falling in 200–300 s (1400–2100 km if a satellite velocity of 7 km/s is considered) occurring in a geomagnetically perturbed period shows more significance than that in a quiet period. Second, statistical work was performed on ion PERs to check their dependence on local time, and it was shown that 24.8% of the perturbations appeared during the daytime (10:30 LT) and 75.2% appeared during the nighttime (22:30 LT). Ionospheric fluctuations with an absolute amplitude of A < 10% tend to be background variations, and the percentages of positive perturbations with a small A < 20% occur at an amount of 64% during the daytime and 26.8% during the nighttime, but this number is reversed for mid–large-amplitude PERs. Large positive PERs with A > 100% mostly occurred at night and negative ones with A < −100% occurred entirely at night. There was a demarcation point in the space size of t = 120 s, and the occurrence probabilities of day PERs were always higher than that of nighttime ones before this point, while this trend was contrary after this point. Finally, distributions of PERs according to different ranges of amplitude and space scale were characterized by typical seasonal variations either in the daytime or nighttime. EIA only exists in the dayside equinox and winter, occupying two low-latitude crests with a lower Np in both hemispheres. Large WSAs appear within all periods, except for dayside summer, and are full of PERs with an enhanced amplitude, especially on winter nights. The WN-like structure is obvious during all seasons, showing large-scale space. On the other hand, several magnetically anomalous zones of planetary-scale non-dipole fields, such as the SAMA, Northern Africa anomaly, and so on, were also successfully detected by extreme negative ion perturbations during this time. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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13 pages, 4619 KiB  
Article
The Lithosphere-Atmosphere-Ionosphere Coupling of Multiple Geophysical Parameters Approximately 3 Hours Prior to the 2022 M6.8 Luding Earthquake
by Chieh-Hung Chen, Shengjia Zhang, Zhiqiang Mao, Yang-Yi Sun, Jing Liu, Tao Chen, Xuemin Zhang, Aisa Yisimayili, Haiyin Qing, Tianya Luo, Yongxin Gao and Fei Wang
Geosciences 2023, 13(12), 356; https://doi.org/10.3390/geosciences13120356 - 21 Nov 2023
Cited by 2 | Viewed by 1852
Abstract
Investigating various geophysical parameters from the Earth’s crust to the upper atmosphere is considered a promising approach for predicting earthquakes. Scientists have observed that changes in these parameters can occur days to months before earthquakes. Understanding and studying the impending abnormal phenomena that [...] Read more.
Investigating various geophysical parameters from the Earth’s crust to the upper atmosphere is considered a promising approach for predicting earthquakes. Scientists have observed that changes in these parameters can occur days to months before earthquakes. Understanding and studying the impending abnormal phenomena that precede earthquakes is both urgent and challenging. On 5 September 2022, a magnitude 6.8 earthquake occurred in Sichuan, China, at 4:52:18 (Universal Time). The earthquake happened approximately 175 km away from an instrumental array established in 2021 for monitoring vibrations and perturbations in the lithosphere, atmosphere, and ionosphere (MVP-LAI). This array consisted of over 15 instruments that regularly monitor changes in various geophysical parameters from the subsurface up to an altitude of approximately 350 km in the ionosphere. Its purpose was to gain insights into the mechanisms behind the coupling of these different geospheres during natural hazards. The seven geophysical parameters from the MVP-LAI system simultaneously exhibited abnormal behaviors approximately 3 h before the Luding earthquake. These parameters include ground tilts, air pressure, radon concentration, atmospheric vertical electric field, geomagnetic field, wind field, and total electron content. The abnormal increase in radon concentration suggests that the chemical channel could be a promising mechanism for the coupling of geospheres. Furthermore, air pressure, the geomagnetic field, and total electron content exhibited abnormal characteristics with similar frequencies. Horizontal wind experienced temporary cessation or weakening, while vertical wind displayed frequent reversals. These anomalies may be attributed to atmospheric resonance before the earthquake. The results demonstrate that the coupling of geospheres, as indicated by the anomalous phenomena preceding an earthquake, could be influenced by multiple potential mechanisms. The multiple anomalies observed in this study provided approximately 3 h of warning for people to prepare for the seismic event and mitigate hazards. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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16 pages, 2926 KiB  
Article
Subduction as a Smoothing Machine: How Multiscale Dissipation Relates Precursor Signals to Fault Geometry
by Patricio Venegas-Aravena and Enrique G. Cordaro
Geosciences 2023, 13(8), 243; https://doi.org/10.3390/geosciences13080243 - 11 Aug 2023
Cited by 5 | Viewed by 1596
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Lithosphere-Atmosphere-Ionosphere Coupling during Earthquake Preparation: Recent Advances and Future Perspectives)
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