On the Statistical Significance of the Variability Minima of the Order Parameter of Seismicity by Means of Event Coincidence Analysis

Christopoulos, Stavros-Richard G.; Skordas, E. S.; Sarlis, N. V.

doi:10.3390/app10020662

Cited by 18 publications

(13 citation statements)

References 107 publications

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“…It is characterized outstanding when AUC is more than 0.9 [ 51 ], which is of course the present case of

since the AUC computed here is around 0.95. This result corroborates with the fact that the statistical significance of the precursory nature of

has been shown by two other independent procedures, in particular Monte Carlo calculations in Reference [ 43 ] and ECA in Reference [ 44 ].…”

Section: Discussionsupporting

confidence: 87%

“…Using Monte Carlo calculations, Sarlis et al [ 43 ] showed that the probability to achieve the above results by chance is of the order of

(we shall return to this point later). This conclusion was also recently strengthened by Christopoulos et al [ 44 ] using the event coincidence analysis (ECA) [ 45 ]. It is the scope of the present paper to investigate the diagnostic accuracy of the precursory minima

before major EQs in Japan during 1984–2011 by employing the area under the receiver operating characteristic (ROC) [ 46 ] curve (AUC), which is a very recent technique for judging the quality of binary predictions.…”

Section: Introductionmentioning

confidence: 77%

“…First, only the minima

of the order parameter fluctuations defined in Equation ( 4 ), but not the minima of

(as claimed in Reference [ 78 ]), are of precursory nature [ 30 , 43 , 44 ].…”

Section: Discussionmentioning

confidence: 99%

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Natural Time Analysis: The Area under the Receiver Operating Characteristic Curve of the Order Parameter Fluctuations Minima Preceding Major Earthquakes

Sarlis

Skordas

Christopoulos

et al. 2020

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It has been reported that major earthquakes are preceded by Seismic Electric Signals (SES). Observations show that in the natural time analysis of an earthquake (EQ) catalog, an SES activity starts when the fluctuations of the order parameter of seismicity exhibit a minimum. Fifteen distinct minima—observed simultaneously at two different natural time scales and deeper than a certain threshold—are found on analyzing the seismicity of Japan from 1 January 1984 to 11 March 2011 (the time of the M9 Tohoku EQ occurrence) 1 to 3 months before large EQs. Six (out of 15) of these minima preceded all shallow EQs of magnitude 7.6 or larger, while nine are followed by smaller EQs. The latter false positives can be excluded by a proper procedure (J. Geophys. Res. Space Physics 2014, 119, 9192–9206) that considers aspects of EQ networks based on similar activity patterns. These results are studied here by means of the receiver operating characteristics (ROC) technique by focusing on the area under the ROC curve (AUC). If this area, which is currently considered an effective way to summarize the overall diagnostic accuracy of a test, has the value 1, it corresponds to a perfectly accurate test. Here, we find that the AUC is around 0.95 which is evaluated as outstanding.

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“…It is characterized outstanding when AUC is more than 0.9 [ 51 ], which is of course the present case of

since the AUC computed here is around 0.95. This result corroborates with the fact that the statistical significance of the precursory nature of

has been shown by two other independent procedures, in particular Monte Carlo calculations in Reference [ 43 ] and ECA in Reference [ 44 ].…”

Section: Discussionsupporting

confidence: 87%

“…Using Monte Carlo calculations, Sarlis et al [ 43 ] showed that the probability to achieve the above results by chance is of the order of

Section: Introductionmentioning

confidence: 77%

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Natural Time Analysis: The Area under the Receiver Operating Characteristic Curve of the Order Parameter Fluctuations Minima Preceding Major Earthquakes

Sarlis

Skordas

Christopoulos

et al. 2020

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“…Natural time analysis is based on a new definition of time introduced in Reference [ 22 ] (see Preface and Chapter 2 of Reference [ 21 ] and in particular its Section 2.1 and Section 2.2 , as well as Reference [ 31 ]) and has been found of usefulness [ 21 ] to uncover important features hidden in complex systems time series spanning various disciplines from cardiology [ 25 , 32 , 33 ] to seismology (including laboratory fracture experiments under well controlled conditions) [ 3 , 4 , 5 , 6 , 34 , 35 , 36 , 37 , 38 ] and from atmospheric sciences [ 39 , 40 ] to complex networks [ 41 ], and civil engineering [ 42 ].…”

Section: Methodsmentioning

confidence: 99%

“…In this analysis, the elapsed time between consecutive events is ignored, but preserving the occurrence order and their energy Q k . For seismic catalogues

, where the moment magnitude [ 43 ] M is used [ 37 , 38 , 44 ]. In natural time we study the evolution of the pair (

) or alternatively (

) where

is the normalized energy for the k -th event.…”

Section: Methodsmentioning

confidence: 99%

Natural Time Analysis of Seismicity within the Mexican Flat Slab before the M7.1 Earthquake on 19 September 2017

Márquez

Ramírez-Rojas

Pérez-Oregon

et al. 2020

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One of the most important subduction zones in the world is located in the Mexican Pacific Coast, where the Cocos plate inserts beneath the North American plate. One part of it is located in the Mexican Pacific Coast, where the Cocos plate inserts beneath the North American plate with different dip angles, showing important seismicity. Under the central Mexican area, such a dip angle becomes practically horizontal and such an area is known as flat slab. An earthquake of magnitude M7.1 occurred on 19 September 2017, the epicenter of which was located in this flat slab. It caused important human and material losses of urban communities including a large area of Mexico City. The seismicity recorded in the flat slab region is analyzed here in natural time from 1995 until the occurrence of this M7.1 earthquake in 2017 by studying the entropy change under time reversal and the variability β of the order parameter of seismicity as well as characterize the risk of an impending earthquake by applying the nowcasting method. The entropy change ΔS under time reversal minimizes on 21 June 2017 that is almost one week after the observation of such a minimum in the Chiapas region where a magnitude M8.2 earthquake took place on 7 September 2017 being Mexico’s largest quake in more than a century. A minimum of β was also observed during the period February–March 2017. Moreover, we show that, after the minimum of ΔS, the order parameter of seismicity starts diminishing, thus approaching gradually the critical value 0.070 around the end of August and the beginning of September 2017, which signals that a strong earthquake is anticipated shortly in the flat slab.

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The Order Parameter Fluctuations of Seismicity Are Minimized Before Major Earthquakes

Varotsos

Sarlis

Skordas

2023

Natural Time Analysis: The New View of Time, Part II

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On the Statistical Significance of the Variability Minima of the Order Parameter of Seismicity by Means of Event Coincidence Analysis

Cited by 18 publications

References 107 publications

Natural Time Analysis: The Area under the Receiver Operating Characteristic Curve of the Order Parameter Fluctuations Minima Preceding Major Earthquakes

Natural Time Analysis: The Area under the Receiver Operating Characteristic Curve of the Order Parameter Fluctuations Minima Preceding Major Earthquakes

Natural Time Analysis of Seismicity within the Mexican Flat Slab before the M7.1 Earthquake on 19 September 2017

The Order Parameter Fluctuations of Seismicity Are Minimized Before Major Earthquakes

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