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 Jou rn al  o f Scientific  Exp lor ati on. Vol.  4 , No. 2, pp. 203-2 1 1 1990 0892-3310190 3.00+.00 ergarnon Press pic. Printed in the USA. 01991 Society for Scientific Exploration Electromagnetic Disturbances Associated With Earthquakes: An Analysis of Ground-Based and Satellite Data  M  I C  H  E  L  P  A  R  ROT  Laboratoire de Physiq ue e t C himie de I Environnement,  450 71 Orleans Cedex 02,  Fr an ce Abstract - Severa l observations wer e made of Ve ry Low Frequency (VLF) emissions apparent ly associated with earthquakes, which we re record ed in- dependently at ground-b ased stati ons and on satellites. The observatio ns at the Ker gue len station (49 26'S, 70°25'E) were made using magnetic anten- nae, on April 24 and 25, 1980, during a period wh en t hree eart hquakes with magnitude M s 4.7 took place near t he stati on. Se veral increases of electro- magnetic w av es at t he ti me of eart hquakes we re recorded on t he polar-orbit- ing satellite AUREOL-3. The observations on the geostationary GEOS-2 satellite w ere made using magnetic and electric antennae during t he period 1977- 19 8 1 . Data we re analysed for t hose cas es w hen both int ense M, 5) earthquakes occurred in the region close to the satellite longitude and the satelli te w as operati ng in the VLF mode. A statisti cal analysis, ba sed o n the enhancement o f wa ve intensit y at the time of earthquakes and usin g GEOS- 2 data, seems to indicate that there is a (possibly indirect) association b e - tween seismic activity and some of the VLF emissions observed at the satellite. Ionosp heric measurement s made from the ground also sh ow ed an increase of the critical frequencyfoE, of the sporadic laye r Es when earth- quakes occurred nearby. Some aspects o f the relation betwee n the VLF emissions and the seismic activity are discussed. Introduction When considering the problem of electrom agnetic emissi ons correlated with earthquakes, one is often face d with an overwhelming problem of com plex- ity, not only because the mechanism of wave generation is not entirely un - derstood, but also because earthqu akes without any emissions are know n t o occur. However, there is a great interest in the subject for the simple reason that when the precursor event occurs it normally does so less than a few hours befo re the shock. A further possibility is that this phenomenon could perhaps be related to other int riguing pr ocesses already obser ved, suc h as the earthquake lights (Derr, 1973) and/or anomalous animal behaviour (Riki- take, 1981). Since the first papers of Gokhberg, Morgunov, Yoshino, and Tomizawa (1982), and Warwick, Stoker, and Mey er (1982), a great deal of theoretical wo rk, and active and pa ssi ve experiments has been done to pro - vide evidence of this short -term precursor. Presented at the Ninth Annual Meeting of the Society for Scientific Exploration, Stanford, ugust 9 -1 1, 1990.

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