Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 4 5/6 2004 10.5194/nhess-4-703-2004 http://www.nat-hazards-earth-syst-sci.net/4/703/2004/ http://www.nat-hazards-earth-syst-sci.net/4/703/2004/nhess-4-703-2004.html http://www.nat-hazards-earth-syst-sci.net/4/703/2004/nhess-4-703-2004.pdf 703 709 2004-11-15 Spectral and multifractal study of electroseismic time series associated to the <i>M<sub>w</sub></i>=6.5 earthquake of 24 October 1993 in Mexico A. Ramírez-Rojas A. Muñoz-Diosdado C. G. Pavía-Miller F. Angulo-Brown &#x00C1;rea de Física de Procesos Irreversibles, Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana Azcapotzalco, 02200, México D. F., México Departameno de Matemáticas, Unidad Profesional Interdisciplinaria de Biotecnología, Instituto Politécnico Nacional, 07340, México D. F., México Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edif. Nº 9, U. P. Zacatenco, 07738, México D.F., México In this work we present a spectral and multifractal study of the electric self-potential fluctuations registered in an electroseismic station located at 100km from the epicenter of an earthquake (EQ) with <i>M<sub>w</sub></i>=6.5 in the Pacific coast of Mexico. Our study suggests that in general the time series analyzed displays a persistent behavior. Our results show an anticorrelation between the spectral exponent &beta; and the width of the multifractal spectrum &Delta;&alpha;, when they are calculated during a time interval of five months (four months before the EQ and one month after the EQ). In addition, we also calculate the time evolution of the correlation coefficient finding that it has a very similar behavior that the time evolution of &Delta;&alpha;.