scholarly journals Phenomena preceding major earthquakes interconnected through a physical model

2019 ◽  
Vol 37 (3) ◽  
pp. 315-324 ◽  
Author(s):  
Panayiotis A. Varotsos ◽  
Nicholas V. Sarlis ◽  
Efthimios S. Skordas
Keyword(s):  
Time Series ◽  
Physical Model ◽  
Order Parameter ◽  
Tohoku Earthquake ◽  
Entropy Change ◽  
Natural Time ◽  
Earth Magnetic Field ◽  
Preceding Period ◽  
Magnetic Field Variations

Abstract. 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. Natural time also enables the determination of the order parameter of seismicity, which is a quantity by means of which one can identify when the system approaches the critical point (the mainshock occurrence is considered the new phase). Applying this analysis, as an example, to the Japanese seismic data from 1 January 1984 until the super-giant M 9 Tōhoku earthquake on 11 March 2011, we find that almost 3 months before its occurrence the entropy change of seismicity under time reversal is minimized on 22 December 2010, which signals an impending major earthquake. On this date the order parameter fluctuations of seismicity exhibit an abrupt increase. This increase is accompanied by various phenomena; e.g., from this date the horizontal GPS azimuths start to become gradually oriented toward the southern direction, while they had random orientation during the preceding period. Two weeks later, a minimum of the order parameter fluctuations of seismicity appears accompanied by anomalous Earth magnetic field variations and by full alignment of the orientations of GPS azimuths southwards leading to the most intense crust uplift. These phenomena are discussed and found to be in accordance with a physical model which seems to explain on a unified basis anomalous precursory changes observed either in ground-based measurements or in satellite data.

scholarly journals Phenomena preceding major earthquakes interconnected through a physical model

2019 ◽  
Author(s):  
Panayiotis A. Varotsos ◽  
Nicholas V. Sarlis ◽  
Efthimios S. Skordas
Keyword(s):  
Time Series ◽  
Physical Model ◽  
Seismic Data ◽  
Order Parameter ◽  
Tohoku Earthquake ◽  
Entropy Change ◽  
Abrupt Increase ◽  
Natural Time ◽  
Preceding Period ◽  
Magnetic Field Variations

Abstract. 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. Applying this analysis, as an example, to the Japanese seismic data from 1 January 1984 until the super-giant M9 Tohoku earthquake on 11 March 2011, we find that almost three months before its occurrence the entropy change of seismicity under time reversal is minimized on 22 December 2010, which signals an impending major earthquake. On this date the order parameter fluctuations of seismicity exhibit abrupt increase. This increase is accompanied by various phenomena, e.g., from this date the horizontal GPS azimuths start to become gradually oriented toward the southern direction, while they had random orientation during the preceding period. Two weeks later, a minimum of the order parameter fluctuations of seismicity appears accompanied by anomalous Earth's magnetic field variations and by full alignment of the orientations of GPS azimuths southwards leading to the most intense crust uplift. These phenomena are discussed and found to be in accordance with a physical model which seems to explain on a unified basis anomalous precursory changes observed either in ground-based measurements or in satellite data.

scholarly journals Determination of the complex frequencies for the normal modes below 1mHz after the 2010 Maule and 2011 Tohoku earthquakes

2014 ◽  
Vol 56 (5) ◽  
Author(s):  
Hao Ding ◽  
Wen-Bin Shen
Keyword(s):  
Time Series ◽  
Normal Modes ◽  
Power Spectra ◽  
Tohoku Earthquake ◽  
Superconducting Gravimeter ◽  
Width Ratio ◽  
Maule Earthquake ◽  
Attenuation Models ◽  
First Time

<p>Based upon SG (superconducting gravimeter) records, the autoregressive method proposed by Chao and Gilbert [1980] is used to determine the frequencies of the singlets of seven spheroidal modes (<sub>0</sub>S<sub>2</sub>, <sub>2</sub>S<sub>1</sub>, <sub>0</sub>S<sub>3</sub>, <sub>0</sub>S<sub>4</sub>, <sub>1</sub>S<sub>2</sub>, <sub>0</sub>S<sub>0</sub>, and <sub>3</sub>S<sub>1</sub>) and the degenerate frequencies of three toroidal modes (<sub>0</sub>T<sub>2</sub>, <sub>0</sub>T<sub>3</sub>, and <sub>0</sub>T<sub>4</sub>) below 1 mHz after two recent huge earthquakes, the 2010 Mw8.8 Maule earthquake and the 2011 Mw9.1 Tohoku earthquake. The corresponding quality factor <em>Q</em>s are also determined for those modes, of which the <em>Q</em>s of the five singlets of <sub>1</sub>S<sub>2</sub> and the five singlets (<em>m</em>=0, <em>m</em>=±2, and <em>m</em>=±3) of <sub>0</sub>S<sub>4</sub> are estimated for the first time using the SG observations. The singlet <em>m</em>=0 of <sub>3</sub>S<sub>1</sub> is clearly observed from the power spectra of the SG time series without using other special spectral analysis methods or special time series from pole station records. In addition, the splitting width ratio <em>R</em> of <sub>3</sub>S<sub>1</sub> is 0.99, and consequently we conclude that <sub>3</sub>S<sub>1</sub> is normally split. The frequencies and <em>Q</em>s of the modes below 1mHz may contribute to refining the 3D density and attenuation models of the Earth.</p>

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

Entropy ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 730 ◽  
Author(s):  
E. Leticia Flores-Márquez ◽  
Alejandro Ramírez-Rojas ◽  
Jennifer Perez-Oregon ◽  
N. V. Sarlis ◽  
E. S. Skordas ◽  
...  
Keyword(s):  
Time Reversal ◽  
Order Parameter ◽  
Pacific Coast ◽  
Entropy Change ◽  
North American Plate ◽  
Cocos Plate ◽  
Mexican Pacific ◽  
Flat Slab ◽  
The North ◽  
Natural Time

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.

Statistical significance of the precursory minima of the order parameter fluctuations of seismicity by modern methods of Statistical Physics

2020 ◽  
Author(s):  
Panayiotis A. Varotsos ◽  
Nicholas V. Sarlis ◽  
Efthimios S. Skordas ◽  
Stavros-Richard G. Christopoulos
Keyword(s):  
Time Series ◽  
Order Parameter ◽  
Statistical Physics ◽  
Statistical Significance ◽  
Time Analysis ◽  
Seismic Electric Signals ◽  
Natural Time ◽  
Natural Time Analysis ◽  
Global Seismicity ◽  
Electric Signals

&lt;p&gt;An order parameter for seismicity was introduced in the frame of natural time analysis [1]. &amp;#160;Recent studies of the fluctuations of this order parameter revealed the existence of minima preceding major earthquakes [2-7]. Here, we review the statistical significance of these minima by using recent methods of Statistical Physics, such as receiver operating characteristics [8] and event coincidence analysis [9,10]. These methods are also applied to the investigation [11] of the statistical significance of Seismic Electric Signals [12].&lt;/p&gt;&lt;p&gt;References&lt;/p&gt;&lt;ol&gt;&lt;li&gt;Varotsos, P.A.; Sarlis, N.V.; 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.&lt;/li&gt; &lt;li&gt;Sarlis, N.V.; Skordas, E.S.; Varotsos, P.A.; Nagao, T.; Kamogawa, M.; Tanaka, H.; Uyeda, S. Minimum of the order parameter fluctuations of seismicity before major earthquakes in Japan, Proc. Natl. Acad. Sci. USA 110 (2013) 13734&amp;#8211;13738, dx.doi.org/10.1073/pnas.1312740110.&lt;/li&gt; &lt;li&gt;Varotsos, P.A.; Sarlis, N.V.; Skordas, E.S. Study of the temporal correlations in the magnitude time series before major earthquakes in Japan. J. Geophys. Res.: Space Physics 119 (2014) 9192&amp;#8211;9206, dx.doi.org/10.1002/2014JA020580.&lt;/li&gt; &lt;li&gt;Sarlis, N.V.; Christopoulos, S.R.G.; Skordas, E.S. Minima of the fluctuations of the order parameter of global seismicity. Chaos 25 (2015) 063110, dx.doi.org/10.1063/1.4922300.&lt;/li&gt; &lt;li&gt;Sarlis, N.V.; Skordas, E.S.; Christopoulos, S.-R.G.; Varotsos, P.A. Statistical significance of minimum of the order parameter fluctuations of seismicity before major earthquakes in Japan, Pure Appl. Geophys. 173 (2016) 165&amp;#8211;172, dx.doi.org/10.1007/s00024-014-0930-8.&lt;/li&gt; &lt;li&gt;Sarlis, N.V.; Skordas, E.S.; Mintzelas, A.; Papadopoulou, K.A. Micro-scale, mid-scale, and macro-scale in global seismicity identified by empirical mode decomposition and their multifractal characteristics. Scientific Reports 8 (2018) 9206, dx.doi.org/10.1038/s41598-018-27567-y.&lt;/li&gt; &lt;li&gt;Mintzelas, A.; Sarlis, N. Minima of the fluctuations of the order parameter of seismicity and earthquake networks based on similar activity patterns. Physica A 527 (2019) 121293, dx.doi.org/10.1016/j.physa.2019.121293.&lt;/li&gt; &lt;li&gt;Fawcett, T., An introduction to ROC analysis, Pattern Recognit. Lett. 27 (2006) 861&amp;#8211;874, dx.doi.org/10.1016/j.patrec.2005.10.010.&lt;/li&gt; &lt;li&gt;Donges, J.; Schleussner, C.F.; Siegmund, J.; Donner, R. Event coincidence analysis for quantifying statistical interrelationships between event time series. The European Physical Journal Special Topics 225 (2016) 471&amp;#8211;487, dx.doi.org/10.1140/epjst/e2015-50233-y.&lt;/li&gt; &lt;li&gt;Siegmund, J.F.; Siegmund, N.; Donner, R.V. CoinCalc - A new R package for quantifying simultaneities of event series. Computers &amp; Geosciences 98 (2017) 64-72, dx.doi.org/10.1016/j.cageo.2016.10.004.&lt;/li&gt; &lt;li&gt;Sarlis, N.V. Statistical Significance of Earth&amp;#8217;s Electric and Magnetic Field Variations Preceding Earthquakes in Greece and Japan Revisited. Entropy 20 (2018) 561, dx.doi.org/10.3390/e20080561.&lt;/li&gt; &lt;li&gt;Varotsos, P.; Lazaridou, M. Latest aspects of earthquake prediction in Greece based on seismic electric signals, Tectonophysics 188 (1991) 321&amp;#8211;347, dx.doi.org/10.1016/0040-1951(91)90462-2.&lt;/li&gt; &lt;/ol&gt;

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

Entropy ◽  
2018 ◽  
Vol 20 (10) ◽  
pp. 757 ◽  
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.

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

2020 ◽  
Author(s):  
Efthimios S Skordas ◽  
Nicholas V. Sarlis ◽  
Mary S Lazaridou-Varotsos ◽  
Panayiotis A Varotsos
Keyword(s):  
Time Reversal ◽  
Tohoku Earthquake ◽  
Entropy Change ◽  
Time Analysis ◽  
Occurrence Time ◽  
Remarkable Change ◽  
Major Earthquake ◽  
Entropy Changes ◽  
Natural Time ◽  
Natural Time Analysis

&lt;p&gt;By analyzing the seismicity in the new time domain termed natural time [1],&amp;#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 &amp;#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].&lt;/p&gt;&lt;p&gt;References&lt;/p&gt;&lt;p&gt;1. Varotsos P.A., Sarlis N.V. and Skordas E.S., &lt;em&gt;Natural Time Analysis: The new view of time. Precursory Seismic Electric Signals, Earthquakes and other Complex Time-Series&lt;/em&gt; (Springer-Verlag, Berlin Heidelberg) 2011.&lt;/p&gt;&lt;p&gt;2. N. V. Sarlis, E. S. Skordas, and P. A. Varotsos, &quot;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&quot;, EPL (Europhysics Letters), 124 (2018), 29001.&lt;/p&gt;&lt;p&gt;3. N. V. Sarlis, E. S. Skordas P. A. Varotsos, A. Ram&amp;#237;rez-Rojas, E. L. Flores-M&amp;#225;rquez, &quot;Natural time analysis: On the deadly Mexico M8.2 earthquake on 7 September 2017&quot;, Physica A 506 (2018), 625-634.&lt;/p&gt;&lt;p&gt;4. P. A. Varotsos, N. V. Sarlis and E. S. Skordas, &quot;Tsallis Entropy Index q and the Complexity Measure of Seismicity in Natural Time under Time Reversal before the M9 Tohoku Earthquake in 2011&quot;, Entropy 20 (2018), 757.&lt;/p&gt;&lt;p&gt;5. A. Ram&amp;#237;rez-Rojas, E. L. Flores-M&amp;#225;rquez, N. V. Sarlis and P. A. Varotsos, &quot;The Complexity Measures Associated with the Fluctuations of the Entropy in Natural Time before the Deadly M&amp;#233;xico M8.2 Earthquake on 7 September 2017&quot;, Entropy 20 (2018), 477.&lt;/p&gt;&lt;p&gt;6. E. S. Skordas, N. V. Sarlis and P. A. Varotsos &amp;#8220;Identifying the occurrence time of an impending major earthquake by means of the fluctuations of the entropy change under time reversal&amp;#8221;, EPL (Europhysics Letters), &lt;em&gt;in press&lt;/em&gt;.&lt;/p&gt;

scholarly journals Statistical and Criticality Analysis of the Lower Ionosphere Prior to the 30 October 2020 Samos (Greece) Earthquake (M6.9), Based on VLF Electromagnetic Propagation Data as Recorded by a New VLF/LF Receiver Installed in Athens (Greece)

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 676
Author(s):  
Dimitrios Z. Politis ◽  
Stelios M. Potirakis ◽  
Yiannis F. Contoyiannis ◽  
Sagardweep Biswas ◽  
Sudipta Sasmal ◽  
...  
Keyword(s):  
Time Series ◽  
Fresnel Zone ◽  
Lower Ionosphere ◽  
Propagation Path ◽  
Northern Coast ◽  
Analysis Method ◽  
Ionospheric Propagation ◽  
Amplitude Data ◽  
Natural Time ◽  
Criticality Analysis

In this work we present the statistical and criticality analysis of the very low frequency (VLF) sub-ionospheric propagation data recorded by a VLF/LF radio receiver which has recently been established at the University of West Attica in Athens (Greece). We investigate a very recent, strong (M6.9), and shallow earthquake (EQ) that occurred on 30 October 2020, very close to the northern coast of the island of Samos (Greece). We focus on the reception data from two VLF transmitters, located in Turkey and Israel, on the basis that the EQ’s epicenter was located within or very close to the 5th Fresnel zone, respectively, of the corresponding sub-ionospheric propagation path. Firstly, we employed in our study the conventional analyses known as the nighttime fluctuation method (NFM) and the terminator time method (TTM), aiming to reveal any statistical anomalies prior to the EQ’s occurrence. These analyses revealed statistical anomalies in the studied sub-ionospheric propagation paths within ~2 weeks and a few days before the EQ’s occurrence. Secondly, we performed criticality analysis using two well-established complex systems’ time series analysis methods—the natural time (NT) analysis method, and the method of critical fluctuations (MCF). The NT analysis method was applied to the VLF propagation quantities of the NFM, revealing criticality indications over a period of ~2 weeks prior to the Samos EQ, whereas MCF was applied to the raw receiver amplitude data, uncovering the time excerpts of the analyzed time series that present criticality which were closest before the Samos EQ. Interestingly, power-law indications were also found shortly after the EQ’s occurrence. However, it is shown that these do not correspond to criticality related to EQ preparation processes. Finally, it is noted that no other complex space-sourced or geophysical phenomenon that could disturb the lower ionosphere did occur during the studied time period or close after, corroborating the view that our results prior to the Samos EQ are likely related to this mainshock.

New determinations of tides on the north-western Ross Ice Shelf

2020 ◽  
pp. 1-14
Author(s):  
Richard D. Ray ◽  
Kristine M. Larson ◽  
Bruce J. Haines
Keyword(s):  
Time Series ◽  
Tide Gauge ◽  
High Rate ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
The North ◽  
Global Positioning ◽  
North Western

Abstract New determinations of ocean tides are extracted from high-rate Global Positioning System (GPS) solutions at nine stations sitting on the Ross Ice Shelf. Five are multi-year time series. Three older time series are only 2–3 weeks long. These are not ideal, but they are still useful because they provide the only in situ tide observations in that sector of the ice shelf. The long tide-gauge observations from Scott Base and Cape Roberts are also reanalysed. They allow determination of some previously neglected tidal phenomena in this region, such as third-degree tides, and they provide context for analysis of the shorter datasets. The semidiurnal tides are small at all sites, yet M2 undergoes a clear seasonal cycle, which was first noted by Sir George Darwin while studying measurements from the Discovery expedition. Darwin saw a much larger modulation than we observe, and we consider possible explanations - instrumental or climatic - for this difference.

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