The Complexity Measures Associated with the Fluctuations of the Entropy in Natural Time before the Deadly México M8.2 Earthquake on 7 September 2017
Alejandro Ramírez-Rojas 1,*, Elsa Leticia Flores-Márquez 2, Nicholas V. Sarlis 3
and Panayiotis A. Varotsos 3
and Panayiotis A. Varotsos 3
1
Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana Azcapotzalco, Av. San Pablo 180, Mexico City 02200, Mexico
2
Instituto de Geofísica, Universidad Nacional Autonoma de Mexico, Mexico City 04510, Mexico
3
Section of Solid State Physics and Solid Earth Physics Institute, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 157 84 Zografos, Greece
*
Author to whom correspondence should be addressed.
Entropy 2018, 20(6), 477; https://doi.org/10.3390/e20060477
Received: 22 May 2018 / Revised: 12 June 2018 / Accepted: 16 June 2018 / Published: 20 June 2018
(This article belongs to the Special Issue Entropy, Nonlinear Dynamics, and Methods of Complex Systems in Earthquake Physics including Precursory Phenomena)
Abstract
We analyse seismicity during the 6-year period 2012–2017 in the new time domain termed natural time in the Chiapas region where the M8.2 earthquake occurred, Mexico’s largest earthquake in more than a century, in order to study the complexity measures associated with fluctuations of entropy as well as with entropy change under time reversal. We find that almost three months before the M8.2 earthquake, i.e., on 14 June 2017, the complexity measure associated with the fluctuations of entropy change under time reversal shows an abrupt increase, which, however, does not hold for the complexity measure associated with the fluctuations of entropy in forward time. On the same date, the entropy change under time reversal has been previously found to exhibit a minimum [Physica A 506, 625–634 (2018)]; we thus find here that this minimum is also accompanied by increased fluctuations of the entropy change under time reversal. In addition, we find a simultaneous increase of the Tsallis entropic index q. View Full-TextKeywords:
earthquakes; natural time analysis; complexity
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Ramírez-Rojas, A.; Flores-Márquez, E.L.; Sarlis, N.V.; Varotsos, P.A. The Complexity Measures Associated with the Fluctuations of the Entropy in Natural Time before the Deadly México M8.2 Earthquake on 7 September 2017. Entropy 2018, 20, 477.
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