Spectral and multifractal study of electroseismic time series associated to the M_w=6.5 earthquake of 24 October 1993 in Mexico

In this work we present a spectral and multifractal study of the electric self-potential fluctuations registered in an electroseismic station located at 100 krn from the epicenter of an earthquake (EQ) with M_w=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 β and the width of the multifractal spectrum Δα, 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 Δα.