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

Shih-Sian Yang; Stelios M Potirakis; Sudipta Sasmal; Masashi Hayakawa

doi:10.3390/e22060674

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

Entropy (Basel). 2020 Jun 17;22(6):674. doi: 10.3390/e22060674.

Authors

Shih-Sian Yang¹, Stelios M Potirakis², Sudipta Sasmal³, Masashi Hayakawa^{4

5}

Affiliations

¹ Institute of Space Science, National Central University, 300 Jhongda Rd., Jhongli District, Taoyuan 32001, Taiwan.
² Department of Electrical and Electronics Engineering, University of West Attica, 250 Thivon and P. Ralli, Aigaleo, GR-12244 Athens, Greece.
³ Indian Centre for Space Physics, 43 Chalantika, Garia St. Road, Kolkata 700084, India.
⁴ Hayakawa Institute of Seismo Electromagnetics, Co. Ltd., University of Electro-Communications (UEC) Alliance Center, 1-1-1 Kojima-cho, Chofu, Tokyo 182-0026, Japan.
⁵ Advanced Wireless & Communications Research Center, UEC, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan.

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.

Keywords: atmospheric gravity waves; criticality; crustal deformation; global navigation satellite system (GNSS); natural time analysis; the 2016 Kumamoto earthquake; time series analysis.