Articles | Volume 4, issue 5/6
Nat. Hazards Earth Syst. Sci., 4, 679–684, 2004

Special issue: Precursory phenomena, seismic hazard evaluation and seismo-tectonic...

Nat. Hazards Earth Syst. Sci., 4, 679–684, 2004

  01 Nov 2004

01 Nov 2004

Analysis of the ULF electromagnetic emission related to seismic activity, Teoloyucan geomagnetic station, 1998-2001

A. Kotsarenko1, R. Pérez Enríquez1, J. A. López Cruz-Abeyro1, S. Koshevaya2, V. Grimalsky3, and F. R. Zúñiga1 A. Kotsarenko et al.
  • 1Centro de Geociencias, Juriquilla, UNAM, Apdo Postal 1-742, Centro Queretaro, Querétaro, Mexico, C.P. 76001, Mexico
  • 2UAEM, Cuernavaca, Morelos, Mexico
  • 3INAOE, Tonantzintla, Puebla, Mexico

Abstract. Results of ULF geomagnetic measurements at station Teoloyucan (Central Mexico, 99.11'35.735''W, 19.44'45.100''N, 2280m height) in relation to seismic activity in the period 1998-2001 and their analysis are presented. Variations of spectral densities for horizontal and vertical components, polarization densities and spectrograms of magnetic field, their derivatives are analyzed as a part of traditional analysis in this study. Values of spectral density were calculated for 6 fixed frequencies f=1, 3, 10, 30, 100 and 300mHz. Fractal characteristics of spectra were analyzed in the conception of SOC (Self-Organized Criticality). 2 nighttime intervals, 0-3 and 3-6h by local time have been used to decrease the noise interference in row data. In order to exclude the intervals with a high geomagnetic activity from analysis we referred to Ap indices, calculated for corresponding time intervals. The contribution of seismic events to geomagnetic emission was estimated by seismic index ks=100.75Ms/10D, where Ms is the amplitude of the earthquake and D is the distance from its epicenter to the station.