Possible New Phenomenon in the Atmospheric Electric Field Intensity Variations that is Caused by the Strong Earthquake Occurrences

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1 Possible New Phenomenon in the Atmospheric Electric Field Intensity Variations that is Caused by the Strong Earthquake Occurrences Abstract Glavatovic Branislav and Cavelis Marin Montenegro Seismological Observatory, Montenegro, Podgorica By using of an electric field fluxmeter with high resolution, a characteristic phenomenon in variations of intensity of atmospheric electric field was detected. This phenomenon occurs within three hours before until three hours after the hypocentral time of the associated strong earthquake. Manifestations of this phenomenon were in a form of an interval where intensity of the atmospheric electric field changing in noticeably narrower range of value. Recorded cases of this phenomenon were lasting from ten minutes until more than two hours. Data about intensity of the atmospheric electric field, which have been recorded in fair weather conditions around the time of occurrences of 264 strong earthquakes were analyzed and this phenomenon is found in the cases 155 earthquakes. Statistical analysis of recorded data shows proportionality between the number of recorded cases of this phenomenon and the magnitude of earthquakes that have been analyzed. Key words: seismo electric phenomena; earthquake; fair weather electric field; electric field mill. Introduction The influence of the seismotectonic activity on the ionosphere behavior and the atmospheric electric field (AEF) were already observed and explained (Nikiforova and Michonovski 1995), Vershinin et.al. (1997), Hao et. al. (2000) and many other authors reported about anomalous changes of intensity of the AEF in fair weather conditions, which have been recorded around the occurrence of strong earthquakes. These changes were recorded in area of epicenter, in form of increasing of the AEF to the value that sometimes exceeding 1000 V/m. Boyarchuk, et.al., 1997 and Pulinets et.al., 1998 were showed that the strong electric field, which appears in first few meter over the ground surface in seismically active region, can change total electrons content in the ionosphere F layer. During the fifteen months, experimental observations were performed, with an idea of discovering anomalous in variations of the AEF around the time of earthquake occurrence. Above mentioned anomalous changes of the intensity were not recorded during this research. However, an unknown phenomenon that has good association with occurrences of strong earthquake had been frequently recorded. Materials and Methods For the monitoring of the AEF variations in this research, an electric field fluxmeter of a well-known "field mill" type was constructed. The principles for construction of this sensor were described in the book "Celija elektrodinamicke indukcije" (Cavelis, 2004). The instrument was installed at the open field of Podgorica, capital of Montenegro, location with the more than 250 fair-weather days per year (42025'49''N; 19015'19''E, 48m above sea level). The sensor was mounted at about two meters over the ground surface. Sensitive plates of the sensor were directed vertically upward, as in every typical measuring of atmospheric electric field with the field mill sensor. The vector of the AEF in fair weather conditions is directed vertically downward and perpendicular on the plates of sensor. In that case, the measured value of electric field flux depends only on the electric field intensity. Therefore, the sensor was calibrated to the electric field intensity and its sensitivity of was adjusted at 0.1mV/Vm-1. For the purpose of continual data acquisition, a digital multimeter with a PC interface, type M-4650 CR, product of Metex (Korea), was coupled on the sensor output. At 200 mv measuring range, which was used in this measuring, this instrument has resolution 0.01 mv. According to the resolution of instrument and the

2 160 E (V/m) 23/06/ M U T (h) Figure 1. Diagram represents a typical phenomenon, which has been observed 23/06/2001 around the time of occurrences of earthquake magnitude M5.7. Interval where AEF intensity becomes almost invariable started just before the hypocentral time (the arrow is pointing on hypocentral time UT). Epicenter of the earthquake was at 1000km distance from measuring place (epicenter coordinate: 35.5N,28.1E). sensitivity of sensor, measuring system had has resolution 0.1Vm -1. For data acquisition was used software delivered by the multimeter manufacturer, which enabled sampling rate of one sample per second. The goal of this research was detecting of characteristic variations of the relative value AEF intensity in correlation with occurrence of strong earthquake. Therefore, the absolute accuracy of the measured value of electric field intensity was not crucial in this research. More important characteristic of the measuring equipment was good stability in work as well as resistance to ambiental variations in longer period. During the construction of sensor we pay attention on these features. Results The most important result of this research is identification of a new phenomenon, whose typical example shows diagram on Figure 1. Displayed event was recorded around the time of a strong earthquake that occurred in Turkey, 1000 km far from the measuring place. As one can see from the diagram, the electric field intensity has decreasing trend at two hours period. About eleven minutes before the hypocentral time, this trend is suddenly changed and the AEF intensity has been almost invariable in about fifteen minutes interval. An interval as this, which appears around the time of occurrence of the earthquake, where has been identified narrower range 1 of changing of the AEF intensity, is the manifestation of phenomenon that was frequently recorded. Registered cases of this phenomenon have been synchronous with strong earthquakes that were occurred in the World. Six examples in Figure 2 illustrate characteristic events of this phenomenon. Shown diagrams are recorded in cases when intensity increasing (Fig. 2a, 2b, 2d), intensity decreasing (Fig. 2f) and fluctuation of intensity of the AEF (Fig. 2c, 2e). Phenomena were occurring during (Fig. 2a, 2b), before (Fig. 2d, 2e, 2f), and after (Fig. 2c) the earthquake. Intervals where we identified narrower range of changing of the AEF intensity have lasted from few minutes to more then two hours, as one can see on examples in this figure. Narrowing of the range of changing of the AEF intensity that were synchronized with occurrence of earthquake have been recorded even in the cases of strong earthquakes that occurred very far from the observation place. An example in Figure 2f illustrates here described phenomenon, which has been 1 The range is the difference between the largest and the smallest observed value. (Statistical definition)

3 Figure 2. Six typical events of the phenomenon are presented in figure. Intervals where was identified narrowing range of the changing of AEF intensity are limited with dashed lines. The arrows point at the hypocentral time of associated earthquake. recorded around the moment of appearing of very strong earthquake, with the epicentre at more than km from the measuring place. Diagram in Figure 3 illustrates the variations of AEF, recorded around the time of the strongest earthquake during the research period (Peru, 23/06/2001, magnitude M 8.4, epicenter coordinates: 16.2S, 73.2W, sensorepicenter distance: 11380km). In this event, we have recorded three intervals with narrow ranges of change of intensity. We analysed data recorded in intervals since five hours before until five hours after the hypocentral time of earthquakes with magnitude larger than M5.5, which were occurred in the World. Figure 3. Dashed lines are limits of three intervals with narrow ranges of change of the AEF intensity. Recorded around the time of occurrence of the earthquake magnitude M8.4, whose hypocentral time is pointed by arrow: UT.

4 According to the NEIC 2 catalogue of seismic events, in researched period from 21/07/2000 to 1/11/2001, in the World had been occurred 577 earthquakes stronger than M 5.5. For this analysis, we used as relevant data that were recorded in the fair-weather conditions at measuring place. Therefore, we analysed onlydata that have been recorded around the time around 264 earthquakes. We found 155 earthquakes that have been in correlation with here-described phenomenon. Data about number of the recorded occurrences of the phenomenon are listed in appendix. All events of this phenomenon were recorded within three hours before until three hours after the earthquake but the most of them within hour before until hour after the earthquake.. Discussion Relatively large number of intervals where we identified narrowing range of changing of intensity of AEF around the moment of earthquake occurrence indicates existence of a new phenomenon % magnitude represents the distribution of number of earthquakes with associated phenomenon in dependence on the earthquake magnitude. This dependence is based on the statistical analysis of data that were acquired around the time of occurrence of earthquakes in the magnitude range between M5.5 and M6.5, which are listed in Table 1. Table 1. Number of the recorded occurrences of the phenomenon and the number of analyzed earthquakes listed in accordance to the magnitude of earthquake. Earthquakes magnitude Number of analyzed earthquakes Number of recorded occurrences of phenomenon > Total: Figure 4. Diagram represents distribution of the number recorded cases of phenomenon in dependence on magnitude of the analysed earthquakes. Trend line indicates proportionality between the magnitude of earthquake and the number of recorded cases of phenomenon. Additionally, dependence between number of registered cases of phenomenon and value of magnitude of analysed earthquakes confirm existence of phenomenon. Diagram in Figure 2 NEIC-National Earthquake Information Canter, USA. The number of analyzed earthquakes with magnitude larger than M6.5 has been insufficient and analyzing these data has no statistical importance. Triangles in Figure 4 represent the percentage of recorded cases of phenomenon in a cumulative sum 3 of number of earthquakes with appropriate value of magnitude. As one can see from diagram, the percentage of earthquakes that have been 3 Sum of all earthquakes with magnitude equal and bigger then the corresponding magnitude.

5 associated with phenomenon increases proportionally with earthquake magnitude value. This proportionality shows that registered phenomenon is regularly connected with occurrence of earthquake. Intervals where AEF intensity varies in narrow range, which have been recorded around the occurrences of earthquake from the whole World, indicate on possibility that this phenomenon with global manifestation. Phenomenon of increasing intensity of the AEF in correlation with occurrence of earthquake, which is mentioned in introduction, appears at distance from epicenter that is proportional to the magnitude of earthquake. According to formula for calculating of this distance (Dobrovolsky et.al, 1979), this phenomenon hasn t been possible to record, because the epicenters of earthquakes that occurred during this research were far from measuring location. 5. Conclusion This paper is presentation of the phenomenon, which is repeatedly recorded within three hours before until three hours after the strong earthquakes. Manifestations of this phenomenon were in the form of interval where was identified noticeably narrower range of changing of the intensity of atmospheric electric field. Recorded events of this phenomenon were lasting from ten minutes until more than two hours. Data about the intensity of AEF, which have been recorded around the time of occurrences of 264 strong earthquakes were analyzed and this phenomenon is found in the 155 cases. Statistical analysis of recorded data shows proportionality between the number of recorded events of this phenomenon and the magnitude of earthquakes. However, it should be notice, that measuring was performed at only one location and in the relatively short period. The statistical confirmation and researching of this phenomenon requires a bigger database, which should be collected in the simultaneous measuring of the AEF at more locations. Appendix: Review of analized earthqukes. References: Boyarchuk K. A., A.M. Lomonosov, S. A. Pulinets, (1997): Electrode Effect Earthquakes Precursor?, BRAS Physics / Supplement Physics of Vibrations, 61 No.3 pp Cavelis M. M., (2004): Electrostatic Field Flux Measuring Using the Electrodynamic Induction Method, in: ETF Journal of Electrical Engineering, Vol. 11. No.1 pp Cavelis M. M., (2000): Ćelija Elektrodinanicke Indukcije, Seizmoloski Zavod, Podgorica, (in Montenegrin). Dobrovolsky IR, S.I. Zubkov, V.I.Myachin (1979): Estimation of the Size of Earthquake Preparation Zone, in: Pageoph. 117 : ,. Hao J., T. Tang and D. Li, (2000): Progress in the research of atmospheric electric field anomaly as an index for short-impending prediction of earthquakes, in: J. Earthquake Pred. Res., 8. No3. pp Nikiforova N.N., S. Michnowski, (1995): Atmospheric electric field anomalies analysis during great Carpatian Earthquakes at Polish Observatory Swider, in: IUGG XXI General Assembly Abstracts. Boulder. Colorado. VA11 D-16. Pulinets S. A., Khegai, V. V., Boyarchuk, K. A., Lomonosov, A. M., (1998): Atmospheric Electric field as a Source of Ionospheric Variability. Physics-Uspekhi, 41, No 5, Vershinin E.A., A.V. Buzevich, K.Yuomoto, Y. Tanaka, (1997): Correlations of Seismic Activity with Electromagnetic Emissions and Variations in Kamchatka Region, International Workshop on Seismo Electromagnetics, University of Electro-Commun. Publ., Chofu, Tokyo, Japan.

6 Date of EQ occurrence Appendix: Review of analized earthquakes Time of EQ occurrence (hh:mm) Epicenter latitude Epicenter longitude Hypocen EQ ter depth Magnitude (km) 1 7/22/ : Intervals in which fair weather electric field intensity varies within narrowed range 19:10-19:30 20:50-21:00 2 7/23/ : /28/2000 5: :10-04: :50 4 7/28/ : :10-19:30 14:50-15:10 5 7/29/ : :50-16:15 6 7/31/ : /31/ : :50-23:10 8 8/3/2000 1: :50-23:10 9 8/3/ : /3/ : :50-19: /4/ : :30-20:00 21:00-22: /6/2000 7: /7/ : :25-15: /9/2000 0: :25-00: /9/ : /12/ : /13/2000 7: :30-07: /15/ : /17/2000 0: /17/ : /18/2000 1: /20/ : :35-22: /21/2000 9: :25-10: /22/ : /22/ : /23/2000 0: /23/ : :30-12: /27/2000 4: /28/ : /28/ : :00-16: /31/2000 8: /2/ : /8/2000 1: /8/ : /11/ : :30-19: /12/2000 0: : /14/ : /16/ : /16/ : /25/2000 4: :50-04: /26/2000 6: :45-05: /26/ : :10-18: /28/ : :50-00: /10/2000 5: :20-07: /12/ : /14/ : :15-19: /21/ : /21/ : :30-14: /21/ : :10-22: /22/2000 1: :20-01: /23/ : :30-21:45 22:20-23: /25/2000 9: :50-09: /25/ : /27/2000 0: :40-23: /27/2000 4:

7 22:30-22: /29/ : :00-00: /30/2000 3: :00-03: /30/ : :45-13: /8/ : /9/2000 5: :50-04: /13/ : /13/ : /14/2000 3: /15/ : /15/ : /16/2000 4: /16/2000 5: /16/2000 5: /16/2000 5: /16/2000 5: /16/2000 5: /16/2000 7: /16/2000 7: /16/2000 7: /16/2000 7: /16/2000 7: /16/2000 9: /16/ : /16/ : /16/ : /16/ : /16/ : /17/2000 1: /17/2000 1: /17/2000 4: /17/ : :35-23: /17/ : :35-23: /17/ : :35-23: /6/ : :10-18: /6/ : :50-01: /15/ : :50-16: /16/ : /23/2000 9: :40-17: /20/ : :55-18: /21/2000 1: :30-01: /21/2000 2: /1/01 6: /2/ : /2/ : :00-24: /6/ : :45-15: /10/ : :55-17: /12/ : /14/ : /15/2001 5: :10-05: /15/2001 5: :10-05: /15/ : :00-12: /16/2001 8: /19/2001 1: /20/ : :00-23: /21/2001 4: :30-06: /23/2001 9: /26/2001 3: :30-04: /26/2001 7: /1/2001 8: /1/ : :50-20: /2/2001 8: /2/ : :50-18: /7/ : :30-11: /7/ : :50-16: /8/2001 5: :45-06:15

8 121 2/9/ : :55-13: /13/ : :00-13:00 19:00-19: /13/ : :00-20: /14/2001 4: :00-05: /14/ : :30-14: /14/ : :30-14: /14/ : :30-14: /17/2001 1: :30-01:00 01:05-01:35 02:00-02: /17/ : :45-18: /17/ : :45-18: /18/ : :15-13: /19/ : :40-14: /21/ : /21/ : /21/ : :20-21:40 22:00-22: /23/2001 0: /7/ : /8/ : :35-20: /11/2001 0: :10-22: /12/ : :15-23: /14/ : :50-19: /15/2001 1: :20-01: /17/2001 7: :30-07: /21/ : :30-22: /4/2001 7: /7/ : :20-00: /9/2001 9: :30-09: /13/ : /25/2001 4: /26/ : :45-20: /26/ : :50-18:00 20:30-21: /3/2001 4: /6/2001 0: /7/2001 0: :00-01: /7/2001 0: :00-01: /8/2001 5: :15-05: /8/ : :10-19: /15/ : /16/2001 0: : /18/2001 2: :05-02: /20/2001 4: :00-04: /21/ : :00-17: /23/ : :50-15: /23/ : :50-22: /24/ : : :00-20: /26/ : :30-11: /28/2001 8: :55-05: /29/ : :40-18: /29/ : :50-23: /30/2001 0: :50-02: /10/2001 1: :30-23: /10/ : :00-11: /13/2001 3: /14/ : :20-19: /14/ : :30-23: /15/2001 6: /15/ : /16/2001 2: :30-01:00 16:10-17: /18/ : :50-19: /23/2001 6: :45-06:58

9 181 6/23/ : :00-14:50 16:00-16: /23/ : :10-17:50 19:10-19: /23/ : :50-19:58 20:30-21; /23/ : /23/ : /23/ : /23/ : /23/ : /23/ : :00-23: /23/ : :10-00: /24/2001 1: /24/2001 2: :45-02: /25/ : :10-22: /26/2001 4: :22-02: /26/ : /26/ : :35-13:50, 197 6/26/ : :00-16: /27/2001 0: :50-19: /29/ : :10-20: /30/ : :40-16: /3/2001 3: /4/ : :30-18: /7/2001 4: /7/2001 9: :40-10: /8/ : :25-16: /12/2001 6: /13/ : :35-19: /17/ : :00-15:50 17:25-17: /19/ : :20-18: /19/ : :15-20: /22/ : /23/2001 2: /24/2001 5: /24/ : /26/2001 0: :30-15:55 16:02-16:15 16:45-16:55 17:25-17:45 16:20-16:55 17:10-17:50 14:15-14: /31/ : :55-15:00 15:10-15: /31/ : :55-16: /5/2001 5: /6/2001 3: /6/2001 3: :25-03:45 05:04-05:20 00:50-01: /9/2001 2: :20-01:35 02:00-02: /9/2001 3: :50-03: /9/ : ;00-13;15 14:15-14: /9/ : /10/ : :55-19: /11/2001 6: :15-05: /15/ : :50-17: /17/ : :55-20: /20/2001 4: :00-05: /21/2001 6: :32-06: /23/ : /24/ : :20-22:10

10 01:25-02: /25/2001 2: :00-03: /27/2001 1: :22-03: /28/2001 6: /28/ : /3/ : :10-21: /11/ : :50-15: /12/2001 8: /12/ : :45-00: /13/2001 3: :30-04:00 23:55-00: /20/2001 2: :45-02: /21/ : :20-23: /22/2001 3: :15-03: /25/ : /25/ : :00-00: /29/2001 2: :10-02:20 03:50-04: /2/2001 0: :10-02: /7/2001 2: :25-02:02 02:25-02: /8/2001 3: /9/ : :45-00: /12/2001 0: :01-00: /12/2001 4: :30-04: /12/2001 5: : /12/ : :00-16: /15/2001 3: :30-01: /16/ : /17/ : /19/2001 3: :00-03: /21/2001 0: /21/2001 3: /26/ : /26/ : /30/2001 3: