E. S. Skordas
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View article: Recent Advances on the VAN Method
Recent Advances on the VAN Method Open
In the 1980s, Varotsos, Alexopoulos and Nomicos (VAN) introduced a short -term earthquake (EQ) prediction method based on measurements of the electric field of the Earth at various locations on the Earth’s surface. The corresponding electr…
View article: Twenty-Five Years After the Chi-Chi Earthquake in the Light of Natural Time Analysis
Twenty-Five Years After the Chi-Chi Earthquake in the Light of Natural Time Analysis Open
Almost two years after the devastating 1999 MW7.6 Chi-Chi earthquake, a new concept of time termed natural time (NT) was introduced in 2001 that reveals unique dynamic features hidden behind the time series of complex systems. In particula…
View article: Possible detection of the onset of flash flooding in Thessaly Greece by measurements of the Earth’s surface electric field
Possible detection of the onset of flash flooding in Thessaly Greece by measurements of the Earth’s surface electric field Open
Since the beginning of 1980s a telemetric network comprising 18 stations in Greece started to measure remotely the transient electric field changes at the Earth’s surface. This article investigates the observed variations of Earth’s electr…
View article: Review of the Natural Time Analysis Method and Its Applications
Review of the Natural Time Analysis Method and Its Applications Open
A new concept of time, termed natural time, was introduced in 2001. This new concept reveals unique dynamic features hidden behind time-series originating from complex systems. In particular, it was shown that the analysis of natural time …
View article: Direct interconnection of seismicity with variations of the Earth's electric and magnetic field before major earthquakes
Direct interconnection of seismicity with variations of the Earth's electric and magnetic field before major earthquakes Open
Upon employing the new concept of time, termed natural time, the analysis of seismicity reveals that, before major earthquakes, the variations of the Earth's electric and/or magnetic field are accompanied by increase of the fluctuations of…
View article: Identifying the Occurrence Time of the Destructive Kahramanmaraş-Gazientep Earthquake of Magnitude M7.8 in Turkey on 6 February 2023
Identifying the Occurrence Time of the Destructive Kahramanmaraş-Gazientep Earthquake of Magnitude M7.8 in Turkey on 6 February 2023 Open
Here, we employ natural time analysis of seismicity together with non-extensive statistical mechanics aiming at shortening the occurrence time window of the Kahramanmaraş-Gazientep M7.8 earthquake. The results obtained are in the positive …
View article: A new e-health cloud-based system for cardiovascular risk assessment
A new e-health cloud-based system for cardiovascular risk assessment Open
Sudden cardiac death (SCD) is one of the leading causes of death worldwide. Many individuals have no cardiovascular symptoms before the SCD event. As a result, the ability to identify the risk before such an event is extremely limited. Tim…
View article: Improving the Estimation of the Occurrence Time of an Impending Major Earthquake Using the Entropy Change of Seismicity in Natural Time Analysis
Improving the Estimation of the Occurrence Time of an Impending Major Earthquake Using the Entropy Change of Seismicity in Natural Time Analysis Open
This article is focused on a new procedure concerning a more accurate identification of the occurrence time of an impending major earthquake (EQ). Specifically, we first recapitulate that, as was recently shown [P. Varotsos et al., Communi…
View article: Earthquake Nowcasting: Retrospective Testing in Greece
Earthquake Nowcasting: Retrospective Testing in Greece Open
Earthquake nowcasting (EN) is a modern method of estimating seismic risk by evaluating the progress of the earthquake (EQ) cycle in fault systems. EN evaluation is based on a new concept of time, termed ’natural time’. EN employs natural t…
View article: Natural Time Analysis: The New View of Time, Part II
Natural Time Analysis: The New View of Time, Part II Open
The book presents analysis in natural time to study the dynamical evolution of a complex system and identifies when the system enters a critical stage
View article: Natural Time Analysis of Global Seismicity
Natural Time Analysis of Global Seismicity Open
Natural time analysis enables the introduction of an order parameter for seismicity, which is just the variance of natural time χ, κ1=⟨χ2⟩−⟨χ⟩2. During the last years, there has been significant progress in the natural time analysis of sei…
View article: Order Parameter and Entropy of Seismicity in Natural Time before Major Earthquakes: Recent Results
Order Parameter and Entropy of Seismicity in Natural Time before Major Earthquakes: Recent Results Open
A lot of work in geosciences has been completed during the last decade on the analysis in the new concept of time, termed natural time, introduced in 2001. The main advances are presented, including, among others, the following: First, the…
View article: Thermodynamics of Point Defects in Solids and Relation with the Bulk Properties: Recent Results
Thermodynamics of Point Defects in Solids and Relation with the Bulk Properties: Recent Results Open
For several decades, the crucial question has arisen as to whether there exists any direct interconnection between the thermodynamic parameters of point defects in solids with the bulk properties of the solid under investigation. To answer…
View article: Earthquake nowcasting: Retrospective testing in Greece 2019 - 2021
Earthquake nowcasting: Retrospective testing in Greece 2019 - 2021 Open
<p>Earthquake nowcasting [1] (EN) is a modern method to estimate seismic risk by evaluating the progress of the earthquake cycle in fault systems [2]. EN employs natural time [3], which uniquely estimates seismic risk by means of the…
View article: Ambient Noise Tomography, Green’s Function and Earthquakes
Ambient Noise Tomography, Green’s Function and Earthquakes Open
Green’s function is well-known, among others, in the application of ambient noise tomography methodologies that may demonstrate the potential of hydrocarbon entrapment in the study area. Here it is also shown to be of key importance in ide…
View article: Estimating the Epicenter of a Future Strong Earthquake in Southern California, Mexico, and Central America by Means of Natural Time Analysis and Earthquake Nowcasting
Estimating the Epicenter of a Future Strong Earthquake in Southern California, Mexico, and Central America by Means of Natural Time Analysis and Earthquake Nowcasting Open
It has recently been shown in the Eastern Mediterranean that by combining natural time analysis of seismicity with earthquake networks based on similar activity patterns and earthquake nowcasting, an estimate of the epicenter location of a…
View article: Estimating the Epicenter of an Impending Strong Earthquake by Combining the Seismicity Order Parameter Variability Analysis with Earthquake Networks and Nowcasting: Application in the Eastern Mediterranean
Estimating the Epicenter of an Impending Strong Earthquake by Combining the Seismicity Order Parameter Variability Analysis with Earthquake Networks and Nowcasting: Application in the Eastern Mediterranean Open
The variance κ1 of the natural time analysis of earthquake catalogs was proposed in 2005 as an order parameter for seismicity, whose fluctuations proved, in 2011, to be minimized a few months before the strongest mainshock when studying th…
View article: Natural Time Analysis of Seismicity within the Mexican Flat Slab before the M7.1 Earthquake on 19 September 2017
Natural Time Analysis of Seismicity within the Mexican Flat Slab before the M7.1 Earthquake on 19 September 2017 Open
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 …
View article: 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 Open
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 parame…
View article: Natural time analysis: Estimation of the occurrence time of a major earthquake from the entropy changes of the preceding seismicity.
Natural time analysis: Estimation of the occurrence time of a major earthquake from the entropy changes of the preceding seismicity. Open
<p>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 &am…
View article: Statistical significance of the precursory minima of the order parameter fluctuations of seismicity by modern methods of Statistical Physics
Statistical significance of the precursory minima of the order parameter fluctuations of seismicity by modern methods of Statistical Physics Open
<p>An order parameter for seismicity was introduced in the frame of natural time analysis [1]. &#160;Recent studies of the fluctuations of this order parameter revealed the existence of minima preceding major earthquakes [2-7]. H…
View article: On the Statistical Significance of the Variability Minima of the Order Parameter of Seismicity by Means of Event Coincidence Analysis
On the Statistical Significance of the Variability Minima of the Order Parameter of Seismicity by Means of Event Coincidence Analysis Open
Natural time analysis has led to the introduction of an order parameter for seismicity when considering earthquakes as critical phenomena. The study of the fluctuations of this order parameter has shown that its variability exhibits minima…
View article: A Prototype Photoplethysmography Electronic Device that Distinguishes Congestive Heart Failure from Healthy Individuals by Applying Natural Time Analysis
A Prototype Photoplethysmography Electronic Device that Distinguishes Congestive Heart Failure from Healthy Individuals by Applying Natural Time Analysis Open
In this paper, a prototype photoplethysmography (PPG) electronic device is presented for the distinction of individuals with congestive heart failure (CHF) from the healthy (H) by applying the concept of Natural Time Analysis (NTA). Data w…
View article: Identifying the occurrence time of an impending mainshock: A very recent case
Identifying the occurrence time of an impending mainshock: A very recent case Open
The procedure by means of which the occurrence time of an impending mainshock can be identified by analyzing in natural time the seismicity in the candidate area subsequent to the recording of a precursory Seismic Electric Signals (SES) ac…
View article: Natural Time Analysis: Results Related to Two Earthquakes in Greece during 2019
Natural Time Analysis: Results Related to Two Earthquakes in Greece during 2019 Open
The following two earthquakes occurred in Greece during 2019: First, a Mw5.4 earthquake close to Preveza city in Western Greece on 5 February and a Mw5.3 earthquake 50 km East of Patras on 30 March. Here, we present the natural time analys…
View article: Phenomena preceding major earthquakes interconnected through a physical model
Phenomena preceding major earthquakes interconnected through a physical model Open
The analysis of earthquake time series in a new time domain termed natural time enables the uncovering of hidden properties in time series of complex systems and has been recently employed as the basis of a method to estimate seismic risk.…
View article: Identifying the Occurrence Time of the Deadly Mexico M8.2 Earthquake on 7 September 2017
Identifying the Occurrence Time of the Deadly Mexico M8.2 Earthquake on 7 September 2017 Open
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 …
View article: Phenomena preceding major earthquakes interconnected through a physical model
Phenomena preceding major earthquakes interconnected through a physical model Open
The analysis of earthquake time series in a new time domain termed natural time enables the uncovering of hidden properties in time series of complex systems and has been recently employed as basis of a method to estimate seismic risk. App…
View article: Geoelectric field and seismicity changes preceding the 2018 Mw6.8 earthquake and the subsequent activity in Greece
Geoelectric field and seismicity changes preceding the 2018 Mw6.8 earthquake and the subsequent activity in Greece Open
A strong earthquake of magnitude Mw6.8 struck Western Greece on 25 October 2018 with epicenter at 37.515N 20.564E. It was preceded by an anomalous geolectric signal that was recorded on 2 October 2018 at a measuring station 70km away from …
View article: Study in Natural Time of Geoelectric Field and Seismicity Changes Preceding the Mw6.8 Earthquake on 25 October 2018 in Greece
Study in Natural Time of Geoelectric Field and Seismicity Changes Preceding the Mw6.8 Earthquake on 25 October 2018 in Greece Open
A strong earthquake of magnitude M w 6.8 struck Western Greece on 25 October 2018 with an epicenter at 37.515 ∘ N 20.564 ∘ E. It was preceded by an anomalous geolectric signal that was recorded on 2 October 2018 at a measuring station 70 k…