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.

Complexity measures and variability of the seismicity monitored whithin the Mexican flat slab before the main shock occurred on 19 September 2017

2020 ◽  
Author(s):  
Alejandro Ramírez-Rojas ◽  
Elsa Leticia Flores-Márquez
Keyword(s):  
North America ◽  
Subduction Zones ◽  
Main Shock ◽  
Plate Boundary ◽  
North American Plate ◽  
Cocos Plate ◽  
Complexity Measures ◽  
Flat Slab ◽  
The North ◽  
Natural Time

<p>Several subduction zones exists in Earth, which have a more or less known dynamic, however each of them has its particularities, as in the case of the Mexican subduction zone, where the flat slab is of special interest. The present flat-slab area is located along the central part of the Cocos-North America plate boundary that the convergence rate between Cocos and North America. The Cocos plate is a remnant of the large Farallon plate, which began to split into smaller plates since 28 Myr ago approximately, when the East Pacific Rise began to interact with the North American Plate. Within such flat slab could be trigger large and destructives earthquakes like the main shock occurred close to Mexico City on September 19, 2017. In this work, we analyze, under the natural time domain, the seismicity registered within the Mexican flat slab since 1995 until the main shock occurred on September 19, 2017. We analyzed the fluctuations of order parameter for seismicity in order to provide some complex measures defined on natural time. Our analysis reveals a possible precursor measure switching on a few weeks before the main shock.  Also we have observed that in the flat slab region the number of earthquakes recorded is lesser than those observed along the total south Pacific Mexican coast.</p>

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.

Species composition and timing of penaeid shrimp postlarvae (Decapoda, Penaeidae) in two zones of the Mexican Pacific coast

Crustaceana ◽  
2014 ◽  
Vol 87 (7) ◽  
pp. 801-813 ◽  
Author(s):  
José A. Félix-Ortiz ◽  
Manuel E. Siu-Quevedo ◽  
Nicolás Castañeda-Lomas ◽  
Guillermo Rodríguez-Domínguez ◽  
Gustavo Rodríguez-Montes de Oca ◽  
...  
Keyword(s):  
Species Composition ◽  
Pacific Coast ◽  
Penaeid Shrimp ◽  
Mesh Size ◽  
Mexican Pacific ◽  
The North ◽  
Sst Variability ◽  
Representative Species ◽  
Gulf Of Tehuantepec ◽  
The Difference

The species composition and variation in density (postlarvae m−3) of penaeid shrimp postlarvae were surveyed every 14 days in two zones of the Mexican Pacific coast; in the north (Mazatlán, 23°N 106°W) and south (Gulf of Tehuantepec, 15°N 95°W). Sampling coincided with full moon and new moon, and they were carried out with plankton net (0.3 m mouth diameter and 450 μm mesh size). Average sea surface temperature (SST) for 1985-1995 increased from Mazatlán (26.2 ± 0.2°C) to Tehuantepec (28.3 ± 0.5°C). The difference in SST between the coldest and warmest month was 7.8°C in Mazatlán and 3.3°C in Tehuantepec. Four species of penaeid shrimp postlarvae were identified: Litopenaeus vannamei (Boone, 1931), L. stylirostris (Stimpson, 1874), Farfantepenaeus californiensis (Holmes, 1900) and F. brevirostris (Kingsley, 1878). There was a regional variation in the species composition. L. vannamei was abundant at both coasts with 40% and F. californiensis varied from south to north from 45 to 36%; the less representative species were L. stylirostris and F. brevirostris, which varied from south to north from 15 to 24%. The occurrence period near Mazatlán is seven months, and it is year-round in Tehuantepec. This study suggests that warm water and low seasonal SST variability facilitate the presence of the shrimp larvae over a longer period.

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

<p>By analyzing the seismicity in the new time domain termed natural time [1],  the entropy changes of seismicity before major earthquakes have been studied. It was found [2-5] that the key quantity is the entropy change ΔS 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].</p><p>References</p><p>1. Varotsos P.A., Sarlis N.V. and Skordas E.S., <em>Natural Time Analysis: The new view of time. Precursory Seismic Electric Signals, Earthquakes and other Complex Time-Series</em> (Springer-Verlag, Berlin Heidelberg) 2011.</p><p>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.</p><p>3. N. V. Sarlis, E. S. Skordas P. A. Varotsos, A. Ramírez-Rojas, E. L. Flores-Márquez, "Natural time analysis: On the deadly Mexico M8.2 earthquake on 7 September 2017", Physica A 506 (2018), 625-634.</p><p>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.</p><p>5. A. Ramírez-Rojas, E. L. Flores-Márquez, N. V. Sarlis and P. A. Varotsos, "The Complexity Measures Associated with the Fluctuations of the Entropy in Natural Time before the Deadly México M8.2 Earthquake on 7 September 2017", Entropy 20 (2018), 477.</p><p>6. E. S. Skordas, N. V. Sarlis and P. A. Varotsos “Identifying the occurrence time of an impending major earthquake by means of the fluctuations of the entropy change under time reversal”, EPL (Europhysics Letters), <em>in press</em>.</p>

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 Unsplit superconducting and time reversal symmetry breaking transitions in Sr2RuO4 under hydrostatic pressure and disorder

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Vadim Grinenko ◽  
Debarchan Das ◽  
Ritu Gupta ◽  
Bastian Zinkl ◽  
Naoki Kikugawa ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Symmetry Breaking ◽  
Time Reversal ◽  
Order Parameter ◽  
Muon Spin Rotation ◽  
Horizontal Line ◽  
Time Reversal Symmetry ◽  
Zero Field ◽  
Symmetry Protected ◽  
Line Node

AbstractThere is considerable evidence that the superconducting state of Sr2RuO4 breaks time reversal symmetry. In the experiments showing time reversal symmetry breaking, its onset temperature, TTRSB, is generally found to match the critical temperature, Tc, within resolution. In combination with evidence for even parity, this result has led to consideration of a dxz ± idyz order parameter. The degeneracy of the two components of this order parameter is protected by symmetry, yielding TTRSB = Tc, but it has a hard-to-explain horizontal line node at kz = 0. Therefore, s ± id and d ± ig order parameters are also under consideration. These avoid the horizontal line node, but require tuning to obtain TTRSB ≈ Tc. To obtain evidence distinguishing these two possible scenarios (of symmetry-protected versus accidental degeneracy), we employ zero-field muon spin rotation/relaxation to study pure Sr2RuO4 under hydrostatic pressure, and Sr1.98La0.02RuO4 at zero pressure. Both hydrostatic pressure and La substitution alter Tc without lifting the tetragonal lattice symmetry, so if the degeneracy is symmetry-protected, TTRSB should track changes in Tc, while if it is accidental, these transition temperatures should generally separate. We observe TTRSB to track Tc, supporting the hypothesis of dxz ± idyz order.

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