Study and validation of VLF / LF data received at the probe receiver station of the Institute of Geophysics, University of Tehran

Document Type : Research


1 M.Sc. Graduated, Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran

2 Assistant Professor, Department of Space Physics, Institute of Geophysics, University of Tehran, Tehran, Iran

3 M.Sc. Graduated, Department of Earth Physics, Institute of Geophysics, University of Tehran, Tehran, Iran


For a long time, two very important issues have been raised for humans in relation to the phenomenon of earthquakes: 1) Predicting the exact time of an earthquake, 2) Controlling the conditions caused by an earthquake. In many advanced societies, valuable work has been done on the second, which has reduced the loss of life and property, but the actions taken on the first have brought us closer to our goal. These measures include studying the tectonic activity of the Earth's crustal plates, investigating changes in wave velocity (P, S) in an area, installing sensors on the ocean floor, monitoring active faults by satellite and using Doppler shift frequency in satellites, studying the behavior of some animals and etc. The mentioned study has laso pointed out that some of them were able to inform us even 15 minutes before the earthquake.
But we are looking for a way that, in addition to being efficient, accurate and comprehensive, can cover a wider area and give us more time before the main earthquake occurs. The study of changes in the characteristics of VLF / LF waves such as signal amplitude, phase signal, temporal and spatial transmissions of the signal along the transmitter-transmitter are cases that have been followed more seriously by Hayakawa et al. since 1995. Since most of the studies have been with the help of VLF wave propagation and less LF waves have been used for investigation and pre-marking, so we want to analyze the first VLF / LF signals arrived at Tehran station in 2019 and also match them with daily density change diagrams. Electrons in terms of time obtained during the signal propagation path from the experimental IRI model associated with each month of the year. The proposed approach in this paper allows us to examine the ability of the IRI model in explaining the temporal evolution of the received signal. Here is a comprehensive way to advance IRI estimates of the current state of the ion sphere. This technique is proven to not only validate the experimental observations of recorded LF and VLF signals at the Tehran station, but also to propose a new approach for improving the estimate of the current state of the ionosphere using the IRI model. More observations could lead to a better estimation of averaged ionospheric densities along the signal propagation path at the morning and evening termination time.
By examining the changes in amplitude and phase of the signal, we examine the amount of charge density and the condition of the lower layer of the sphere ion (layer D) along the propagation path of the waves. We are looking for signs to reach a premonition for other earthquakes that will occur in the future. This approach could be used as an indicator of pre-seimic activities produced through the well-known Lithosphere-Atmosphere -Ionosphere coupling (LAIC) process. Such a methodology could lead to a solid approach for earthquake prediction in Iran using the physics-based analogy. Therefore, this study investigated a new technique for ionosphere remote sensing as well as a new approach for earthquake prediction in Iran.


Main Subjects

الهی سرشت، م. ۱۳۹۷، بررسی اثر فعالیت‌های پیش لرزه‌‌ای در سیگنالهای VLF ثبت شده در گیرنده تهران، پایان‌نامه کارشناسی‌ارشد، دانشگاه تهران.
Dey S. and Singh R., 2003, Surface Latent Heat flux as an earthquake precursor, Natural Hazards and Earth System Sci., 3, 749-755.
Gufeld, A., Rozhnoi, A., Tyumentsev, S. N., Sherstyuk, S. V. and Yampolsky, V. S., 1992, Disturbances of Radiowave Fields before the Rudbar and Rachinsk Earthquakes, Izv. Akad. Nauk, Ser. Fiz. Zemli, 3, 102–106.
Gokhberg, M.B., Gufeld, I.L., Rozhnoy, A.A., Marenko, V.F., Yampolsky, V.S. and Ponomarev, E.A., 1989, Study of seismic influence on the ionosphere by super long Wave probing of the Earth–ionosphere waveguide. Physics of Earth and PlanetaryInteriors, 57, 64–67.
Hayakawa, M., Molchanov, O.A., Ondoh, T. and Kawai, E., 1996, The precursory signature effect of the Kobe earthquake on VLF subionospheric signals. J. Comm. Res.
Kumar A., Kumar S., Hayakawa M. and Menk F., 2013, Subionospheric VLF perturbations observed at lowlatitude associated with earthquake from Indonesia region. Journal of Atmospheric and Solar-Terrestrial Physics, 102, 71-80.
Mil’kis M. R., 1986, Meteorological Precursors of Earthquakes, Izvestiya, Earth Physics, 22, 195-204.
Mogi, K., 1984, Temporal variation of crustal deformation during the days preceding a thrust-type great earthquake The 1944 Tonankai earthquake of magnitude 8.1, Japan. PAGEOPH 122, 765–780.
Pulinets, S.A. and Boyarchuk, K., 2004, Ionospheric Precursors of Earthquakes. Springer, Berlin, 315 pp.
Pulinets S. A., Kotsarenko A. N., Ciraolo L. and Pulinets I. A., 2007, Special case of Ionospheric day-to-day variability associated with earthquake preparation, Adv. Space Res., 39 (5), 970-977.
Pulinets S. A., Ouzounov D., Karelin A.V., Boyarchuk K. A. and Pokhmelnykh L. A., 2006, The physical nature of the thermal anomalies observed before strong earthquakes,Physics and Chemistry of the Earth, 31, 143-153, 2006bBased on the subionospheric LF propagation data in Japan, Ann. Geophys., 24, 2219–2225, doi: 10.5194/angeo-24-2219-2006.
Rozhnoi, A., Solovieva, M., Molchanov, O., Schwingenschuh, K., Boudjada, M., Biagi, P. F., Maggipinto, T., Castellana, L., Ermini, A., and Hayakawa, M., 2009, Anomalies in VLF radio signals prior the Abruzzo earthquake (M = 6.3) on 6 April 2009, Nat. Hazards Earth Syst. Sci., 9, 1727– 1732, doi: 10.5194/nhess-9-1727-2009.
Svensmark, H., 2006, Experimental evidence for the role of ions in particle nucleation under atmospheric conditions, published: 03 October 2006 -17.
Sasmal S., Chakrabarti S. K. and Chakrabarti S., 2010, Studies of the correlation Between ionospheric anomalies and seismic activities in the Indian subcontinent, AIP Conference Proceedings, 1286, 270–290.