The Basics Of Seismo-Ionospheric Coupling

Transcription

1 The Basics Of Seismo-Ionospheric Coupling Sergey Pulinets Institute of Geophysics, National Autonomous University of Mexico (UNAM) Mexico 106

2 It is now well acknowledged that atmospheric electricity plays important role in the atmosphere-ionosphere coupling. The anomalous electric field was measured by different groups in different seismically active regions in the world several days/hours before the seismic shock. Figure 1 (a,b,c) demonstrates the different examples of the anomalous electric field measurements. In all cases the common feature is the presence of the electric field direction change and the field amplitude span exceeding 1000 V/m. We can discuss the possible mechanisms of such field generation [4,5], but the experimental fact of its existence one cannot neglect Fig. 1 Examples of anomalous atmospheric field measurements before the strong earthquakes. a measurements at Swider observatory (Poland) before the Vrancha earthquake on [1]; b measurements at Kamchatka peninsula in June 1996 before earthquake with M=7 [2]; c measurements at Baodi observatory (China) before the Youzhou earthquake M L =4.7 on [3] 107

3 Sergey Pulinets It was shown in [6] that the field of such order can penetrate into the ionosphere and create the large and small scale irregularities. Two parameters are very important for the electric field penetration effectiveness: the field intensity and the area occupied by the anomalous field. It means that the weaker field but with large spatial parameters could create the stronger effects within the ionosphere than the very strong field but the small size. Due to high conductivity along the geomagnetic field lines the anomalous electric field will be mapped onto all levels of the ionosphere and the magnetosphere. It creates irregularities in E-region of the ionosphere in the form of sporadic E-layers, generates the AGW and small scale irregularities on the heights of order 200 km, creates the large scale variations on the heights of F-layer of the ionosphere, creates the field aligned irregularities within the magnetospheric tube loaned onto the region of the anomalous electric field. The VLF emissions of different origin became to be scattered into the modified magnetospheric tube, what creates the increased level of VLF emissions within these tubes registered by the satellites. The increased intensity of VLF emission leads to wave particle interaction on cyclotron resonance in the equatorial plane of the magnetosphere and as a result the losscone precipitation of energetic particles. The precipitating particles create the additional ionization layer on the heights of D-region of the ionosphere. This additional layer serves as a reflector for the VHF FM broadcasting radiowaves providing their over horizon propagation registered also experimentally. This scenario of seismo-ionospheric coupling is reflected in the Fig

4 Fig. 2 Seismo-ionospheric coupling physical mechanism scenario Except the electron concentration variations observed within the ionosphere and magnetosphere, the other parameters of the space plasma modification are observed, especially the mean ion mass modification. It is observed experimentally the increased concentration of the light ions within the ionosphere in comparison with undisturbed conditions. This effect did not accept the proper physical explanation yet, but probably it is connected with the modification by anomalous electric field of the plasmaspheric fluxes of atomic oxygen. Neverthesless, we can state that in general the physical nature of seismoionospheric coupling is clear now and we can deliberately and in the way of purposefulness construct the future experiments for studies of the short term ionospheric precursors of the disastrous earthquakes. REFERENCES 1. N. N. Nikiforova, S. Michnowski, Atmospheric electric field anomalies analysis during great Carpatian Earthquakes at Polish Observatory Swider, IUGG XXI 109

5 Sergey Pulinets General Assembly Abstracts, Boulder, Colorado, VA11D-16, Vershinin E.F., Buzevich A.V., Yumoto K., Saita K., Tanaka Y., Correlations of seismic activity with electromagnetic emissions and variations in Kamchatka region, in Atmospheric and Ionospheric Electromagnetic Phenomena Associated with Earthquakes, Edited by M. Hayakawa, Terra Scientific Publishing Company, Tokyo: pp , Hao J., Tang T. and Li D., Progress in the research of atmospheric electric field anomaly as an index for short-impending prediction of earthquakes, J. Earthquake Pred. Res., 8, No. 3, pp , K.A.Boyarchuk, A.M.Lomonosov, S.A.Pulinets, V.V.Hegai, Variability of the Earth's Atmospheric Electric field and Ion-Aerosol Kinetics in the Troposphere, Studia Geophysica et Geodaetica, 42, pp , F. Freund, A. Gupta, S. Butow, S. Tenn, Molecular Hydrogen and Dormant Charge Carriers in Minerals and Rocks, in Atmospheric and Ionospheric Electromagnetic Phenomena Associated with Earthquakes, Edited by M. Hayakawa, Terra Scientific Publishing Company, Tokyo: pp , S. A. Pulinets, K. A. Boyarchuk, V. V. Hegai, V. P. Kim and A. M. Lomonosov, Quasielectrostatic Model of Atmosphere-Thermosphere-Ionosphere Coupling, Adv. Space Res., 26, No 8, pp ,