Seismic Physicochemical Anomalies in the Atmosphere and Upper Atmosphere: Causal Relationship to the Geological Environment

Dear Colleagues,

During the preparatory phase of an earthquake, dynamic changes such as deep low-frequency tremors and microseismic activity begin within the fault zone of the focal region. As this process progresses, various physicochemical anomalies occur, including the ascent of groundwater and gases, increases in the temperature of the subsurface, and fluctuations in electrical conductivity, telluric currents, and the electric potential. Furthermore, these anomalies may extend to the surface and atmosphere, manifesting as charged aerosols, abnormal animal behavior, electromagnetic emissions, and luminous phenomena. In the upper atmosphere, anomalies in the total electron content of the ionosphere and nocturnal airglow have also been reported.

If these anomalies can be captured through scientific observation methods, they may provide insights into their relationship with seismic activity. However, many macroscopic anomalies documented in historical earthquake records remain unexplained due to a lack of scientific verification.

These anomalous phenomena are considered to result from the release of a portion of the significant dynamic energy accumulated in the fault prior to an earthquake, which is then converted into chemical, thermal, and luminous energy. Accordingly, the larger the earthquake, the more pronounced the anomalies, and numerous cases have been recorded with modern observation instruments. At the same time, phenomena such as earthquake lights have also been observed during relatively small earthquakes, suggesting that changes in the geological environment of the focal region may influence the occurrence of these anomalies. However, this relationship has yet to be fully elucidated.

This Special Issue aims to clarify the causal relationship between these physicochemical anomalies and the geological environment of the focal region. By integrating observational data, theoretical analysis, laboratory experiments, and investigations of historical earthquakes, we seek to unravel the mechanisms behind these anomalies and explore their potential applications for earthquake prediction, disaster prevention, and mitigation. Additionally, through an analysis of eyewitness testimonies and historical records of past earthquakes, we aim to identify the geological characteristics of focal regions in which similar phenomena have been observed, thereby contributing to the verification of related hypotheses.

We hope that this Special Issue will serve as a platform for the integration of physics, chemistry, and geology in order to enhance our understanding of earthquake precursor phenomena. We look forward to receiving your contributions.

Prof. Dr. Yuji Enomoto
Prof. Dr. Katsumi Hattori
Guest Editors

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• physicochemical anomalies
• earthquake precursors
• liposphere–atmosphere–ionosphere coupling
• seismic–electromagnetic effects
• earthquake lights
• tectonic activity and gas emissions
• historical earthquake records