Critical Dynamics in Stratospheric Potential Energy Variations Prior to Significant (M > 6.7) Earthquakes

Abstract

Lithosphere–atmosphere–ionosphere coupling (LAIC) is studied through various physical or chemical quantities, obtained from different sources, which are observables of the involved complex processes. LAIC has been proposed to be achieved through three major channels: the chemical, the acoustic, and the electromagnetic. Accumulated evidence supporting the acoustic channel hypothesis has been published, while atmospheric gravity waves (AGWs) play a key role in LAIC as the leading mechanism for the transmission of energy from the lower atmosphere to the stratosphere and mesosphere, associated with atmospheric disturbances observed prior to strong earthquakes (EQs). The seismogenic AGW is the result of temperature disturbances, usually studied through stratospheric potential energy (EP). In this work, we examined 11 cases of significant EQs (M > 6.7) that occurred during the last 10 years at different geographic areas by analyzing the temperature profile at the wider location of each one of the examined EQs. The “Sounding of the Atmosphere using Broadband Emission Radiometry” (SABER) instrument, part of the “Thermosphere Ionosphere Mesosphere Energetics Dynamics” (TIMED) satellite, data were employed to compute the potential energy (EP) of the AGW. Using the temperature profile, we first calculated EP and determined the altitudes’ range for which prominent pre-seismic disturbances were observed. Subsequently, the EP time series at specific altitudes, within the determined “disturbed” range, were for the first time analyzed using the criticality analysis method termed the “natural time” (NT) method in order to find any evidence of an approach to a critical state (during a phase transition from a symmetric phase to a low symmetry phase) prior to the EQ occurrence. Our results show criticality indications in the fluctuation of EP a few days (1 to 15 days) prior to the examined EQs, except from one case. In our study, we also examined all of the temperature-related extreme phenomena that have occurred near the examined geographic areas, in order to take into account any possible non-seismic influence on the obtained results.

Observation of the Preparation Phase Associated with Mw = 7.2 Haiti Earthquake on 14 August 2021 from a Geophysical Data Point of View

“…An external and occasional hazard that may affect the results, especially atmospheric analyses, is the eventual presence of extreme weather events, such as storms or hurricanes. In the literature, the identified pre-earthquake anomalies have been compared with hurricanes to exclude the ones probably not induced by earthquakes [96]. In the investigated time, NOAA reported several storms and hurricanes in the Atlantic Ocean sector (https://www.nhc.noaa.gov/data/tcr/index.php?season=2021&basin=atl, last access 10 March 2024) as reported in the following list.…”

Lower-ionosphere anomalies prior to strong earthquakes that occurred in north-central mainland Greece on March 2021 as revealed by multi-method analysis of VLF sub-ionospheric propagation data

“…including VLF sub-ionospheric propagation data has been presented in detail in [Potirakis et al, 2021]. Also, newer studies using the NT time series method to other observable quantities of LAIC have shown existence of critical dynamics before EQs [Ghosh et al, 2021;Yang et al, 2020;Politis et al, 2022]. Furthermore, a very recent application of NT time series method to global seismicity is given by Christopoulos et al [2022].…”

“…Such studies have revealed that different layers of the model reach critical state before a strong EQ occurrence. Specifically, the criticality analysis method called "natural time" (NT) analysis has successfully been applied to VLF subionospheric propagation data, ULF magnetic field data, global navigation satellite system deformation (GNSS) data, surface latent heat flux (SLHF) data and very recently in stratospheric potential energy ( ), as well to other EQ-related observables such as pre-EQ seismic electric signals (SES), foreshock seismicity, MHz fracto-EM Emissions, also known as fracto-EM Radiation, (FEME/FEMR), [e.g., Politis et al, 2021Politis et al, , 2022Potirakis et al, 2013Potirakis et al, , 2018aPotirakis et al, , 2021Yang et al, 2020;Ghosh et al, 2021;Varotsos et al, 2011, Eftaxias et al, 2018. Additionally, another criticality analysis method called "method of critical fluctuations" (MCF) has been also applied in VLF subionospheric propagation data, MHz FEME/FEMR recordings and ULF magnetic field data [Politis et al, 2021;Potirakis et al, 2016Potirakis et al, , 2018bPotirakis et al, , 2019Contoyiannis et al, 2004a].…”

Coordinated Symmetrical Altitude Position and Attitude Control for Stratospheric Airship Subject to Strong Aerodynamic Uncertainties

“…The stratosphere is the altitude range between 10 km and 50 km above the ground, and wherein the atmosphere mainly flows at the horizontal direction. Within this altitude range, the air tends to be dry, resulting in steady movement and providing excellent visibility with low humidity [1]. Exploiting these favorable conditions, the stratospheric airship emerges as an extraordinary aerostatic vehicle capable of flying at extremely low speeds for extended durations.…”