NATURAL TIME AND SEISMIC ELECTRIC SIGNALS P.A. Varotsos, N.V. - PowerPoint PPT Presentation

NATURAL TIME AND SEISMIC ELECTRIC SIGNALS P.A. Varotsos, N.V. Sarlis, E.S. Skordas and M.S. Lazaridou Solid State Section and Solid Earth Physics Institute, Department of Physics, University of Athens, Panepistimiopolis, Zografos 15784, Athens, Greece. Email: pvaro@otenet.gr 1

Summary of the properties of Natural Time. Introduction Seismic Electric Signals What happened before the 4 major Earthquakes in Greece during 2008 2

Seismic Electric Signals (SES ) (VAN method, 1981) We measure both the electric field and the magnetic field 1. ≤ 1Hz 2. Several measuring dipoles (pairs of electrodes, ~2m) L ≈ a few tens of meters (short dipoles) to a few tens of kilometers (long dipoles) Δ V Δ V/L ≈ constant Δ V’ single SES SES activity 3

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SES physical properties since 1984, P. Varotsos & K. Alexopoulos Tectonophysics 110, 73-125 (1984) 1. Sensitive points SES are recorded only at certain sites of the Earth’s surface …. detailed experimentation is necessary. 2. Selectivity …Each sensitive site records SES only from certain seismic areas (selectivity map) For a given pair: “SES station – seismic region”: 3. Ε = const EW Ε NS (polarity: constant) (2) + (3) epicentral determination ⎛ Δ ⎞ V ≈ − + ⎜ ⎟ log ( 0 . 3 0 . 4 ) M const 4. ⎝ L ⎠ which leads to the determination of magnitude 5

100 (a) L’ s -I 80 L’ E (10 -6 V/m) 60 40 L E c -W c 20 N c -S c 0 6:30 6:40 6:50 7:00 7:10 7:20 7:30 7:40 7:50 April 19, 1995 (UT) 140 (b) 120 B EW 100 V m (10 -3 V) 80 60 B NS 40 20 0 6:30 6:40 6:50 7:00 7:10 7:20 7:30 7:40 7:50 April 19, 1995 (UT) (c) 5 0 N c -S c -5 E (10 -6 V/m) V m (10 -3 V) -10 40 20 -15 0 B EW -20 -20 -40 6:50 6:51 6:52 6:53 6:54 6:55 April 19, 1995 (UT) Varotsos, P., Sarlis, N. and E. Skordas, Electric fields that “arrive” before the time-derivative of the magnetic field prior to major earthquakes, Phys. Rev. Lett. 91 , 148501 (2003) 6

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During the last decade: (a) When the expected magnitude is around 6.0 or larger, the SES activities are submitted for publication to International Journals well in advance (b) Three additional SES physical properties have been found 8

Dipoles at Volos Station P. Varotsos, N. Sarlis, and E. Skordas, " Α note ο n the spatial extent of the Volos SES sensitive 9 site", Acta Geophysica Polonica , Vol. 49 (2001), 425-435.

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11 Attention 2 nd order phase transition

propagation station d diffusion h diffusion Source See page 184 of P. Varotsos, The Physics of Seismic Electric Signals , TerraPub, Tokyo, 2005 12

SES transmission model suggested E O by Varotsos and Alexopoulos [1986] d=100km The dipole source may be parallel ρ ο H (B) or perpendicular to the ρ f neighbouring conductive path. D 100km source 50m The case A exhibits “over- h=100m 5km 100km A amplification”. D source w Varotsos and Alexopoulos [1986] suggested that A is more probable E O than B; this seems to coincide with d=100km the recent aspects that there is always H a significant component of the ρ ο emitting dipole perpendicular to the ρ f D conductive path source 100km 50m h=100m 5km B 200km D w source 13

When the SES is emitted, the current follows the most conductive channel through which most of this current travels; since the emitting source lies near a channel of high conductivity, if the measuring station lies at a site close to the upper end of the conductive channel, the observed electric field (E) is order(s) of magnitude stronger than in the case of a homogeneous or horizontally layered earth. Actually, numerical solutions of Maxwell equations (Sarlis et al., , Geoph. Res. Lett. 26 , 3245, 1999), being in full agreement with analytical solutions (Varotsos et al. J. Appl. Phys . 83 , 60, 1998), indicate that, within a certain region (i.e., above the end of the channel), at distances r ~ 100km from EQs of magnitude M 5.5-6.0, the electric field may reach detectable values (5-10 mV/km). This explains why the SES observations revealed the so called selectivity effect. 14

NATURAL TIME ( φυσικός χρόνος ) It was suggested by P. Varotsos, N. Sarlis and E. Skordas, Practica of Athens Academy 76 , 294 (2001). It extracts signal information as much as possible Phys. Rev. Lett . 94 , 170601 (2005) Ion current fluctuations in Discrimination of SES Similar looking signals that are activities (strongest memory) membrane channels. emitted from systems with from noise emitted from All SES activities fall on a different dynamics can be nearby artificial sources universal curve (critical distinguished. Phys.Rev.E 67 , 021109 (2003) dynamics) Modern techniques of statistical Phys.Rev.E 66 , 011902 (2002) physics, e.g., Hurst Analysis, Earthquakes: Wavelet transform, Detrended •The seismicities of various Fluctuation Analysis (DFA) etc. Analysis of electrocardiograms countries fall on a universal should be better made in natural in natural time: curve. time. The sudden cardiac death •Order parameter Phys. Rev. E 68 , 031106 (2003) individuals are distinguished from •Studying the seismicity after the truly healthy ones as well as an SES activity, we can from patients. •High Tc-superconductors determine the time-window Phys. Rev. E 70 , 011106 (2004) •Small changes in the of the impending mainshock Phys. Rev. E 71 , 011110 (2005) magnetic field can result in with good accuracy of a few Appl. Phys. Lett. 91 , large rearrangements of hours to a few days. 064106(2007) fluxing the sample, known as Phys. Rev. E 72 , 041103 flux avalanches (2005); Phys. Rev. E 73 , • Rice piles The entropy S changes to S- 031114 (2006); Phys. Rev. E 74, 021123 (2006); Journal of ( S elf O rganized C riticality) under time reversal . Applied Physics 103 , 014906 Phys.Rev.E 71 , 032102 (2005) Phys.Rev.B 73 , 054504 (2006) 15 (2008)

16 P. Varotsos, N. Sarlis, and E. Skordas, Practica of Athens Academy 76 , 294 (2001)

Physical Review E 70, 011106 (2004) & Physical Review E 71, 011110 (2005) 17

18 Practica of Athens Academy 76 , 294 (2001)

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The entropy in natural time S ≡〈 χ ln χ 〉 - 〈 χ 〉 ln 〈 χ 〉 ( Varotsos et al., Practica of Athens Academy 76 , 294 (2001); Phys. Rev. E. 68 , 031106 (2003); ibid 70 , 011106 (2004)) S is a dynamic entropy and hence differs essentially from the usual static entropy: Shannon: - Σ p i ln p i When reversing the time arrow, S changes to S- ( casual operator) Varotsos et al., Phys. Rev. E 71, 032102 (2005) For criticality : Both S and S- are smaller than that of a ( ) = − = “uniform” distribution S ln 2 2 1 4 0 . 0966 u 21

Varotsos et al., Phys. Rev. E 70 , 011106 (2004) Varotsos et al., Phys. Rev. E 71 , 011110 (2005) 22

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1 st usefulness of Natural Time Several Modern Procedures to distinguish true preseismic signals ( critical dynamics) from “artificial” noise: 2 � Normalized power spectrum Π ( ω ) ( or κ = χ − χ ) 2 1 � Hurst � Detrended Fluctuation Analysis (DFA) � Multifractal DFA � Wavelet Transform � Entropy ATTENTION: All the above in natural time We now present each of them 24

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1 1 S E S 0.8 a c t i v i t i e s 0.975 0.6 noises noises Π(φ) S E S a c 0.95 t 0.4 i v 0 0.05 0.1 i t i e s theory 0.2 biological membrane 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 φ natural frequency The normalized power spectra for SES activities (dotted lines) and artificial noises (broken Π ( φ ) 1 lines). They correspond to and , respectively. The lower solid curve κ 1 ≈ κ ≤ ≈ 0 . 07 0 . 0833 1 12 corresponds to the ICFMCs (labeled biological membrane), while the upper solid curve to the theoretical estimation for critical phenomena. For the sake of clarity, the curve corresponding to the 1 “uniform” distribution ( ) was not drawn: this lies very close and only slightly below the κ = κ = 1 u 12 26 ICFMCs. The inset refers to the range . ≤ φ ≤ 0 0 . 1 SES activities Universality!!! Universality!!!

Entropy in natural time 0.12 (a) AN 0.08 ICFMC < χ q > - < χ > q 0.04 SES 0 2 κ = χ − χ 2 -0.04 1 q =2 -0.08 0 0.5 1 1.5 2 q 0.15 (b) ICFMC 0.1 < χ q ln χ > - < χ > q ln< χ > 0.05 SES 0.12 0 0.10 0.08 -0.05 0.06 -0.1 0.04 0.7 1.0 1.3 Entropy q =1 -0.15 0 0.5 1 1.5 2 27 q Varotsos et al., Phys. Rev. E 68 , 031106 (2003)