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IGRA Bucharest ROMANIA

Real time electromagnetic monitoring system used for short-term earthquakes forecast related to the seismic-active Vrancea zone D. STANICA and D. A. STANICA Institute of Geodynamics of the Romanian Academy - IGRA. IGRA Bucharest ROMANIA.

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IGRA Bucharest ROMANIA

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  1. Real time electromagnetic monitoring system used for short-term earthquakes forecast related to the seismic-active Vrancea zone D. STANICAandD. A. STANICA Institute of Geodynamics of the Romanian Academy - IGRA IGRA Bucharest ROMANIA

  2. OUTLINE :SEISMIC ACTIVE VRANCEA ZONE1. Intermediate depth earthquakes (Eqs.)THEORETICAL CONCEPT OF THE EM PRECURSORS1. Normalized function Bzn and its geodynamic implication - the concept Cause (resistivity variations) – Pre-seismic effect (Bzn anomalous);  DATA COLLECTION, PROCESSING AND ANALYSIS1. Real-TimeGround Based Monitoring System and data transfer installed at the GOPS;2. FFT band-pass filter analysis in the frequency range 0.001 Hz to 0.0083 Hzof the normalized function Bzn ;3. Statistical analysis based on the standardized random variable equation to extract pre-seismic anomalous intervals reflected by Bzn* Results1. Bzn* time series and pre-seismic anomalous intervals related to M≥4Eqs (February 2013- December 2015)Conclusions

  3. Seismic active Vrancea zoneIntermediate depth earthquakes Topography crust 6.9 7.2 7.7 7.2 Major last earthquakes Seismic tomography with the isosurface of 2.2% P-wave velocity anomaly(S. Cloetingh and the ISES team, 2007)

  4. Seismic active Vrancea zone Shaking map with contour lines ( Mercalli Intensity) for M7.2 Eq.

  5. 3D MT resistivity lithospheric tomographic imagesemphasizing the torsion process of the Vrancea seismogenicvolume(Stanica et al. 2004) 3D resistivity image(crust) 3D resistivity image(upper mantle) Descending Asthenospheric Currents Due to the torsion process, solid rocks of the seismogenic volumegenerate increases of the stress what leads to: rocks dehydration; rupturing process and release of electric charges. The electric charges carried by water moving through the faulting system - acting as high sensitive path (CECA) - generate currents of high intensity that, in their turn, create disturbances of the magnetic field monitorized at GOPS

  6. Basic theoretical concept of the EMprecursors

  7. Normalized function Bzn and the concept cause (resistivity variation) – effect (Bzn anomalous) For a 2D structure the vertical magnetic component (Bz) is produced mainly by the magnetic component perpendicular to strike (B┴) and their normalized function Bzn (f) = Bz (f) / B┴ (f) , (1) should be time invariant for a given 2D structure in non seismic conditions (Ward et al., 1970) and it becomes instable some days before an EQ (Stanica and Stanica 2010, 2011 ). In terms of resistivity, we also may compute: ρz(f)=0.2/f .│E║(f)/Bz(f)│2, (2) ρ║(f)= 0,2/f .│E║(f)/B┴(f)│2 , (3) where: f is frequency [Hz] and E║ is electric field parallel to the strike [V/m] In terms of resistivity: │Bzn(f) │= [ρ║(f)/ ρz(f)]1/2 (4) n = ρ║(f)/ ρz(f) (5) Bzn anomalouscould be linked withthe resistivity variationinto the Earth lithosphere

  8. DATA COLLECTION Ground-Based EM Monitoring System and Real-Time Data Transfer Installed at Geodynamic Observatory Provita de Sus (GOPS)

  9. GSM ANTENNA Central System for Data Processing and Analyses INTERNET UNIDIRECTIONNAL ANTENNA G3 TRANSMISSION GBMS ADU-06 24 bit MAG-03 DAM 24 bit REZISTIVIMETER INTEL V3 E N E V E E Hz E S Hx A M N B Hx Hy Hy Electric field sensors DC Electric and magnetic field sensors (low frequency) Magnetic field sensors (low frequency) Hz Ground-Based EM Monitoring System-Installed at GOPS ADU-06 and “MAPROS”software packages have been used to validate2-D geoelectrical structure and its strike orientation at GOPS Geomagnetic System used for continuous monitoring of the components B┴ and Bz, with a sampling rate of 60s

  10. DATA PROCESSING AND ANALYSING • 2D geoelectrical structure validation • - GOPS is placed on the CECA which is generated by • a 2D structurein the frequency range 0.001-0.0083Hz; • 2. A FFT band-pass filter analysis, in the frequency range 0.001-0.0083Hz, has been performed for two successive time windows of 1024 samples, with 60% overlapping, on the entirely time series of 1440 data points acquired each day ; • 3. The new geomagnetic time series were used to calculate the daily averaged values of the normalized function Bzn and its standard deviation (STDEV) ;

  11. 2D geoelectrical structure validationGOPS is placed on the CECA that is generated by a 2D structure (for 0.001-0.0083Hz) GOPS CECA Vrancea Induction vector (Wiese) zone

  12. FFT band-pass filter analysis in the frequency range 0.001 Hz to 0.0083 Hzfor two successive windows of 1024 samples, with 60% overlappingon the entirely Bzn time series of 1440 data set, recorded each day 60% OVERLAPING Bzn on 13 March 2014

  13. Bzn time series and STDEV for 2015

  14. Bzn time series and Earthquakes magnitude for 2015

  15. Where: is five days raning average of Bzn is 30 days running average of Bzn; is 30 days running average of STDEV is the anomalous distribution of Bzn and delineates the threshold for anomaly using STDEV Pre-seismic intervals identificationusing astandardized random variable equation (Bzn*)

  16. Results In this study, it is considered that in pre - seismic conditions the Bzn has an anomalous behavior, due to the lithospheric resistivity changes, generated by the torsion processes of the seismogenic volume, associated with increase stress and fluid flow through the high conductivity path (CECA) extended to the GOPS

  17. Bzn* time series and pre-seismic anomalous intervals related to Eqs of M≥4 (February 2013- December 2015) 4

  18. Bzn* time series and pre-seismic anomalous intervals related to Eqs of M≥5(February 2013- December 2015)

  19. GOPS 6.9/27km Bzn* time series and pre-seismic anomalous interval related to Aegean Sea crustal earthquake of M≥6.9, on May 24, 2014

  20. Distribution of the earthquake with M 4 Vrancea zone (2013-2015) 3D EQ DISTRIBUTION EPICENTRAL EQ DISTRIBUTION D e p t h[km] L a t i t u d e L o n g i t u d e

  21. CONCLUSIONS: • The proposed methodology provided adequate information to identify the pre-seismic anomalous intervals of Bzn*, related to the M≥4.0earthquakes occurred in Vrancea Zone during the period 2013-2015; • The time scale of the observed anomalous variations is from few days to weeks before the onset of the seismic events.

  22. THANK YOU !

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