Natural time analysis: Estimation of the occurrence time of a major earthquake from the entropy changes of the preceding seismicity.

By analyzing the seismicity in the new time domain termed natural time [1],&#160; the entropy changes of seismicity before major earthquakes have been studied. It was found [2-5] that the key quantity is the entropy change &#916;S under time reversal, which is minimized a few months before major earthquakes such as the M9.0 Tohoku earthquake [2] on 11 March 2011 and the M8.2 Chiapas earthquake [3] in Mexico on 7 September 2017; accompanied by an abrupt increase of its fluctuations [4,5]. Here we discuss how these fluctuations may lead to a procedure through which the occurrence time of an impending mainshock can be estimated [6].References1. Varotsos P.A., Sarlis N.V. and Skordas E.S., Natural Time Analysis: The new view of time. Precursory Seismic Electric Signals, Earthquakes and other Complex Time-Series (Springer-Verlag, Berlin Heidelberg) 2011.2. N. V. Sarlis, E. S. Skordas, and P. A. Varotsos, "A remarkable change of the entropy of seismicity in natural time under time reversal before the super-giant M9 Tohoku earthquake on 11 March 2011", EPL (Europhysics Letters), 124 (2018), 29001.3. N. V. Sarlis, E. S. Skordas P. A. Varotsos, A. Ram&#237;rez-Rojas, E. L. Flores-M&#225;rquez, "Natural time analysis: On the deadly Mexico M8.2 earthquake on 7 September 2017", Physica A 506 (2018), 625-634.4. P. A. Varotsos, N. V. Sarlis and E. S. Skordas, "Tsallis Entropy Index q and the Complexity Measure of Seismicity in Natural Time under Time Reversal before the M9 Tohoku Earthquake in 2011", Entropy 20 (2018), 757.5. A. Ram&#237;rez-Rojas, E. L. Flores-M&#225;rquez, N. V. Sarlis and P. A. Varotsos, "The Complexity Measures Associated with the Fluctuations of the Entropy in Natural Time before the Deadly M&#233;xico M8.2 Earthquake on 7 September 2017", Entropy 20 (2018), 477.6. E. S. Skordas, N. V. Sarlis and P. A. Varotsos &#8220;Identifying the occurrence time of an impending major earthquake by means of the fluctuations of the entropy change under time reversal&#8221;, EPL (Europhysics Letters), in press.

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A remarkable change of the entropy of seismicity in natural time under time reversal before the super-giant M9 Tohoku earthquake on 11 March 2011

EPL (Europhysics Letters) ◽

10.1209/0295-5075/124/29001 ◽

2018 ◽

Vol 124 (2) ◽

pp. 29001 ◽

Cited By ~ 17

Author(s):

N. V. Sarlis ◽

E. S. Skordas ◽

P. A. Varotsos

Keyword(s):

Time Reversal ◽

Tohoku Earthquake ◽

Remarkable Change ◽

Natural Time

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Erratum: A remarkable change of the entropy of seismicity in natural time under time reversal before the super-giant M9 Tohoku earthquake on 11 March 2011

EPL (Europhysics Letters) ◽

10.1209/0295-5075/126/19901 ◽

2019 ◽

Vol 126 (1) ◽

pp. 19901

Author(s):

N. V. Sarlis ◽

E. S. Skordas ◽

P. A. Varotsos

Keyword(s):

Time Reversal ◽

Tohoku Earthquake ◽

Remarkable Change ◽

Natural Time

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M W9 Tohoku earthquake in 2011 in Japan: precursors uncovered by natural time analysis

Earthquake Science ◽

10.1007/s11589-017-0189-0 ◽

2017 ◽

Vol 30 (4) ◽

pp. 183-191 ◽

Cited By ~ 5

Author(s):

Panayiotis A. Varotsos ◽

Nicholas V. Sarlis ◽

Efthimios S. Skordas ◽

Mary S. Lazaridou-Varotsos

Keyword(s):

Tohoku Earthquake ◽

Time Analysis ◽

Natural Time ◽

Natural Time Analysis

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Fluctuations of the entropy change under time reversal: Further investigations on identifying the occurrence time of an impending major earthquake

EPL (Europhysics Letters) ◽

10.1209/0295-5075/130/29001 ◽

2020 ◽

Vol 130 (2) ◽

pp. 29001 ◽

Cited By ~ 5

Author(s):

P. A. Varotsos ◽

E. S. Skordas ◽

N. V. Sarlis

Keyword(s):

Time Reversal ◽

Entropy Change ◽

Occurrence Time ◽

Major Earthquake

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Tsallis Entropy Index q and the Complexity Measure of Seismicity in Natural Time under Time Reversal before the M9 Tohoku Earthquake in 2011

Entropy ◽

10.3390/e20100757 ◽

2018 ◽

Vol 20 (10) ◽

pp. 757 ◽

Cited By ~ 16

Author(s):

Panayiotis Varotsos ◽

Nicholas Sarlis ◽

Efthimios Skordas

Keyword(s):

Phase Transitions ◽

Time Reversal ◽

Scaling Laws ◽

Tohoku Earthquake ◽

Entropy Change ◽

Characteristic Size ◽

Natural Time ◽

Minority Phase ◽

Earthquake Scaling ◽

Precursory Change

The observed earthquake scaling laws indicate the existence of phenomena closely associated with the proximity of the system to a critical point. Taking this view that earthquakes are critical phenomena (dynamic phase transitions), here we investigate whether in this case the Lifshitz–Slyozov–Wagner (LSW) theory for phase transitions showing that the characteristic size of the minority phase droplets grows with time as t 1 / 3 is applicable. To achieve this goal, we analyzed the Japanese seismic data in a new time domain termed natural time and find that an LSW behavior is actually obeyed by a precursory change of seismicity and in particular by the fluctuations of the entropy change of seismicity under time reversal before the Tohoku earthquake of magnitude 9.0 that occurred on 11 March 2011 in Japan. Furthermore, the Tsallis entropic index q is found to exhibit a precursory increase.

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Natural time analysis: Important changes of the order parameter of seismicity preceding the 2011 M9 Tohoku earthquake in Japan

EPL (Europhysics Letters) ◽

10.1209/0295-5075/125/69001 ◽

2019 ◽

Vol 125 (6) ◽

pp. 69001 ◽

Cited By ~ 9

Author(s):

P. A. Varotsos ◽

N. V. Sarlis ◽

E. S. Skordas

Keyword(s):

Order Parameter ◽

Tohoku Earthquake ◽

Time Analysis ◽

Natural Time ◽

Natural Time Analysis

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Identifying the occurrence time of an impending major earthquake by means of the fluctuations of the entropy change under time reversal

EPL (Europhysics Letters) ◽

10.1209/0295-5075/128/49001 ◽

2020 ◽

Vol 128 (4) ◽

pp. 49001 ◽

Cited By ~ 2

Author(s):

E. S. Skordas ◽

N. V. Sarlis ◽

P. A. Varotsos

Keyword(s):

Time Reversal ◽

Entropy Change ◽

Occurrence Time ◽

Major Earthquake

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Identifying the Occurrence Time of the Deadly Mexico M8.2 Earthquake on 7 September 2017

Entropy ◽

10.3390/e21030301 ◽

2019 ◽

Vol 21 (3) ◽

pp. 301 ◽

Cited By ~ 3

Author(s):

Nicholas Sarlis ◽

Efthimios Skordas ◽

Panayiotis Varotsos ◽

Alejandro Ramírez-Rojas ◽

Elsa Flores-Márquez

Keyword(s):

Order Parameter ◽

Earthquake Occurrence ◽

Dynamic Features ◽

Time Analysis ◽

Occurrence Time ◽

Dynamic Phase ◽

Natural Time ◽

Natural Time Analysis ◽

Dynamic Phase Transition ◽

System Approaches

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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