AbstractPrecursory phenomena in the ionosphere, atmosphere and groundwater before large earthquakes (M>6.5) are extensively investigated toward the earthquake prediction. Upward tornado type seismic clouds occurred near the epicenter associated with strong LF-VLF radio noises from lightning discharges in the evening of January 9, 1995 [Yamada, T., Oike, K. On the increase of electromagnetic noises before and after the 1995 Hyogo-Ken Nanbu earthquake. In: Hayakawa M. (Ed.), Atmospheric and Ionospheric Electromagnetic Phenomena Associated with Earthquakes. TERRAPUB, Tokyo, pp. 417–427, 1999] and anomalous foEs increases up to 10MHz were detected at Shigaraki, 90km of the epicenter and at Kokubunji, 500km east of the epicenter [Ondoh, T. Anomalous sporadic-E layers observed before M7.2 Hyogo-ken Nanbu earthquake; Terrestrial gas emanation model. Adv. Polar Upper Atmos. Res. 17, 96–108, 2003; Ondoh, T. Anomalous sporadic-E ionization before a great earthquake, Adv. Space Research 34, 1830–1835, 2004] associated with strong ELF noises from lightning discharges in the daytime on January 15, 1995 [Hata, M., Fujii, T., Takumi, I. EM precursor of large-scale earthquakes in Japan, in: Abstracts of International Workshop on Seismo Electromagnetics (IWSE 2005), Univ. Electro-Communications, Chofu, Tokyo, Japan, March 15–17, pp. 182–186, 2005] before the M7.2 Hyogoken–Nanbu earthquake of January 17, 1995. The anomalous foEs increases occurred at epicentral distances within 500km that are the same as those of the terrestrial gas emanations along active faults before large earthquakes [King, C.-Y. Gas geochemistry applied to earthquake prediction: An overview. J. Geophys. Res. 91(B12), 12269–12281, 1986]. The anomalous foEs increases seem to be a seismic precursor because geomagnetic and solar conditions were very quiet all day on January 15,1995 and the normal foEs in Japanese winter is below 6MHz. No significant pre-seismic geomagnetic field variation was detected at epicentral distance of 100km before this earthquake [Ondoh, T., Hayakawa, M. Anomalous occurrence of sporadic-E layers before the Hyogoken–Nanbu earthquake, M7.2 of January 17, 1995. In: Hayakawa, M. (Ed.), Atmospheric and Ionospheric Electromagnetic Phenomena Associated with Earthquakes, TERRAPUB, Tokyo, pp. 629–639, 1999; Ondoh, T., Hayakawa, M. Seismo discharge model of anomalous sporadic E ionization before great earthquakes. In: Hayakawa, M., O.A. Molchanov, (Eds.), Seismo Electromagnetics: Lithosphere–Atmosphere–Ionosphere Couplings, TERRAPUB, Tokyo, pp. 385–390, 2002; Ondoh. T., Hayakawa, M. Synthetic study of precursory phenomena of the M7.2 Hyogo-ken Nanbu earthquake. Phys. Chem. Earth 31, 378–388, 2006]. The foF2 decrease and h’F increase occurred before the M7.8 Hokkaido Nansei-Oki earthquake of July 12,1993 in a geomagnetic quiet period [Ondoh, T. Ionospheric disturbances associated with great earthquake of Hokkaido southwest coast, Japan of July 12, 1993. Phys. Earth Planet. Interiors. 105, 261–269, 1998; Ondoh, T. Seismo ionospheric phenomena. Adv. Space Res. 26, 8, 1267–1272, 2000]. Characteristic phase changes at terminator times of Omega 10.2kHz waves passing 70km of the epicenter extended toward darker local times by 1h for 3 days before this earthquake due to lowering of the wave reflection height or ion density increases in the D region [Hayakawa, M., Molchanov, O. A., Ondoh, T., Kawai, E. The precursory signature effect of the Kobe earthquake on VLF subionospheric signals. J. Commun. Res. La., 43, 00. 169–180, 1996]. The radon concentration in the atmosphere over Ashiya fault, Kobe [Yasuoka, Y., Shinogi, M. Anomaly in atmospheric radon concentration: a possible precursor of the 1995 Kobe, Japan, earthquake. Health Phys. 72(5), 759–761, 1997] and in the groundwater at 17m well in Nishinomiya, Japan [Igarashi, G., Saeki, S., Takahata, N., Sumikawa, K., Tasaki, S., Sasaki, Y., Takahashi, M., Sano, Y. Ground-water radon anomaly before the Kobe earthquake in Japan. Science 269, 60–61, 1995] had gradually increased since 2 months before the M7.2 earthquake, increased suddenly in December 1994, and rapidly returned to the normal low level of October, 1994 [Yasuoka, Y., Shinogi, M. 1997. Anomaly in atmospheric radon concentration: a possible precursor of the 1995 Kobe. Japan, earthquake. Health Phys. 72(5), 759–761.]. Radon concentration changes in the groundwater before the M 7.0 Izu-Oshima-kinkai earthquake, Japan on January 14, 1978 [Wakita, H., Nakamura, Y., Notsu, K., Noguchi, M., Asada, T. 1980. Radon anomaly: a possible precursor of the 1978 Izu-Oshima-kinkai earthquake. Science 207, 882–883] and the M6.8 Chengkung earthquake, Taiwan on December 10, 2003 [Kuo, T., Fan, K., Chen, W., Kuochen, H., Han, Y., Wang, C., Chang, T., Lee, Y. Radon anomaly at the Antung Hot Spring before the Taiwan M6.8 Chengkung earthquake. Proceedings, Thirty-First Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, January 30–February 1, 2006, SGP-TR-179, 2006] are also investigated to find common features of the groundwater radon concentration changes before large earthquakes (M>6.5) in comparison with those before the M7.2 Hyogoken–Nanbu earthquake. Groundwater radon concentrations before the 3 large earthquakes had shown common characteristic changes of gradually initial ones from the normal level since about 2 months before the earthquake onsets, rapid decreases down to the minimum, and quick increases up to the maximum at 7–20 days before the earthquake onsets, respectively. These are very useful characteristics of pre-seismic radon anomaly for the earthquake prediction or warning. Promising observations toward the earthquake prediction are also discussed.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Investigation of precursory phenomena in the ionosphere, atmosphere and groundwater before large earthquakes of M>6.5


    Contributors:
    Ondoh, T. (author)

    Published in:

    Advances in Space Research ; 43 , 2 ; 214-223


    Publication date :

    2008-04-10


    Size :

    10 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English