Possible seismogenic origin of changes in the ULF EM resonant structure observed at the Teoloyucan geomagnetic station, Mexico, 1999–2001

1Kotsarenko, AN, 2Molchanov, ОA, 1Enriquez, RPerez, 1Cruz-Abeyro, JALopez, 3Koshevaya, SV, 4Grimalsky, VV
1Center for Earth Sciences (UNAM), Mexico
2Earth Physics Institute of O.Yu. Schmidt of the Russian AS, Moscow, Russia
3Faculty of Chemistry, Autonomous University of Morelo (UAEM), Mexico
4National Institute of Astrophysics, Optics and Electronics, Mexico
Kosm. nauka tehnol. 2005, 11 ;(5-6):030-034
Publication Language: English
The evolution of the ULF resonant structure observed at the Teoloyucan geomagnetic station is studied in a possible relation with seismic activity in Mexico in 1999–2001. Two resonant lines were observed in the H-component (linear polarization) in the frequency bands fR2 = 10.2...11.1 mHz and fR2 = 13.6...14.5 mHz, sometimes accompanied by satellite lines. The source of the observed resonances is possibly related with the geomagnetic location of the station (geomagnetic latitude λ =29.1°) and its proximity to the equatorial electrojet (λ=30°). An enhancement of the carrier frequency of both resonances in the period from one month to two weeks was found before the strongest EQs. Also, a depression of the resonant structure just a few days before and a few days after some EQs seems to be correlated with seismic activity.
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