Natural Time Analysis of Global Navigation Satellite System Surface Deformation: The Case of the 2016 Kumamoto Earthquakes

Abstract

In order to have further evidence of the atmospheric oscillation channel of the lithosphere-atmosphere-ionosphere coupling (LAIC), we have studied criticality in global navigation satellite system (GNSS) surface deformation as a possible agent for exciting atmospheric gravity waves (AGWs) in the atmosphere and GNSS fluctuations in the frequency range of AGWs with the use of the natural time (NT) method. The target earthquake (EQ) is the 2016 Kumamoto EQ with its main shock on 15 April 2016 (M = 7.3, universal time). As the result of the application of the NT method to GNSS data, we found that for the one-day sampled GNSS deformation data and its fluctuations in two AGW bands of 20–100 and 100–300 min, we could detect a criticality in the period of 1–14 April, which was one day to two weeks before the EQ. These dates of criticalities are likely to overlap with the time periods of previous results on clear AGW activity in the stratosphere and on the lower ionospheric perturbation. Hence, we suggest that the surface deformation could be a possible candidate for exciting those AGWs in the stratosphere, leading to the lower ionospheric perturbation, which lends further support to the AGW hypothesis of the LAIC process.

Contaminated Effect of Geomagnetic Storms on Pre-Seismic Atmospheric and Ionospheric Anomalies during Imphal Earthquake

“…It is also evident from Figures 7-10 that there is also example of post seismic AGW excitation. This could have several reasons starting from several aftershocks and many other meteorological phenomena [43] [59].…”

Estimating the Epicenter of a Future Strong Earthquake in Southern California, Mexico, and Central America by Means of Natural Time Analysis and Earthquake Nowcasting

“…Natural time was introduced [ 5 ] in 2001 as a general method to analyze time-series resulting from complex systems [ 7 ]. It has been applied to a variety of fields, such as condensed matter physics [ 22 , 23 , 24 ], geophysics [ 6 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ], civil engineering [ 35 , 36 , 37 , 38 ], climatology [ 39 , 40 , 41 , 42 ], and biomedical engineering [ 43 , 44 ]. Within the concept of NTA, it has been shown that the variance of natural time may be considered as an order parameter for seismicity [ 3 , 45 , 46 , 47 , 48 , 49 ] as well as in acoustic emission before fracture [ 28 , 50 ] or in other self-organized critical phenomena such as ricepiles [ 51 ] and avalanches in the Olami–Feder–Christensen [ 52 ] earthquake model [ 53 ] or in the Burridge–Knopoff [ 54 ] train model [ 55 ].…”

Lithosphere–Atmosphere–Ionosphere Coupling Effects Based on Multiparameter Precursor Observations for February–March 2021 Earthquakes (M~7) in the Offshore of Tohoku Area of Japan

“…In the old days, when we proposed the AGW hypothesis, we were always criticized that there is no evidence of surface deformation before an EQ. Recently, there have been several important published papers on the pre-EQ surface deformation based on the GPS, seismic measurements [55,[98][99][100][101]. Chen et al (2020) [99] found clear fluctuations in the frequency range in the earth's surface deformation before large EQs, and suggested the presence of an AGW resonator in the lithosphere.…”

“…As is given in Hayakawa et al (2004) [32], the first is so-called chemical channel, in which emanation of radioactive radon and/or gases is considered to play the main player, leading to the modification of atmospheric conductivity and generation of electric field, thereby driving a variation in the ionospheric plasma density [7,28,35,[46][47][48][49]. The second is acoustic channel, in which atmospheric oscillations, including atmospheric gravity waves (AGWs) and acoustic wave, are excited by the precursory deformation of ground motion and/or gas emanation [8,33,[50][51][52][53], propagating upwards to the lower and upper ionosphere and leading to a perturbation in the ionosphere [54][55][56][57]. The third is electromagnetic channel [32], where electromagnetic waves generated in any frequency range propagate upwards into the ionosphere and magnetosphere, inducing the particle precipitation into the upper atmosphere due to wave-particle interactions in the magnetosphere (e.g., [58][59][60][61]).…”

“…In [62], they tried to interpret various observables in the context of positive hole hypothesis. Many papers using subionospheric sounding with the VLF/LF technique have been published, providing a lot of indirect evidence on the AGW hypothesis [21,22,51,52,[63][64][65][66][67], but recent studies on the AGW activity in the stratosphere have given convincing direct support to this AGW hypothesis [53][54][55][56][57].…”