Identifying the Occurrence Time of the Deadly Mexico M8.2 Earthquake on 7 September 2017
by
Nicholas V. Sarlis 1,2,*
, 
Efthimios S. Skordas 1,2, Panayiotis A. Varotsos 1,2, Alejandro Ramírez-Rojas 3 and Elsa Leticia Flores-Márquez 4
Nicholas V. Sarlis 1,2,*, Efthimios S. Skordas 1,2, Panayiotis A. Varotsos 1,2, Alejandro Ramírez-Rojas 3 and Elsa Leticia Flores-Márquez 4
1
Section of Solid State Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 157 84 Zografos, Athens, Greece
2
Solid Earth Physics Institute, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 157 84 Zografos, Athens, Greece
3
Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana Azcapotzalco, Av. San Pablo 180, Mexico City 02200, Mexico
4
Instituto de Geofísica, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
*
Author to whom correspondence should be addressed.
Entropy 2019, 21(3), 301; https://doi.org/10.3390/e21030301
Received: 9 February 2019 / Revised: 15 March 2019 / Accepted: 16 March 2019 / Published: 20 March 2019
(This article belongs to the Special Issue Entropy, Nonlinear Dynamics, and Methods of Complex Systems in Earthquake Physics including Precursory Phenomena)
It has been shown that some dynamic features hidden in the time series of complex systems can be unveiled if we analyze them in a time domain termed natural time. In this analysis, we can identify when a system approaches a critical point (dynamic phase transition). Here, based on natural time analysis, which enables the introduction of an order parameter for seismicity, we discuss a procedure through which we could achieve the identification of the occurrence time of the M8.2 earthquake that occurred on 7 September 2017 in Mexico in Chiapas region, which is the largest magnitude event recorded in Mexico in more than a century. In particular, we first investigated the order parameter fluctuations of seismicity in the entire Mexico and found that, during an almost 30-year period, i.e., from 1 January 1988 until the M8.2 earthquake occurrence, they were minimized around 27 July 2017. From this date, we started computing the variance of seismicity in Chiapas region and found that it approached the critical value 0.070 on 6 September 2017, almost one day before this M8.2 earthquake occurrence.
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Keywords:
natural time analysis; order parameter of seismicity; entropy change under time reversal; entropy; critical point
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MDPI and ACS Style
Sarlis, N.V.; Skordas, E.S.; Varotsos, P.A.; Ramírez-Rojas, A.; Flores-Márquez, E.L. Identifying the Occurrence Time of the Deadly Mexico M8.2 Earthquake on 7 September 2017. Entropy 2019, 21, 301.
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