Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 5 1 2005 10.5194/nhess-5-63-2005 http://www.nat-hazards-earth-syst-sci.net/5/63/2005/ http://www.nat-hazards-earth-syst-sci.net/5/63/2005/nhess-5-63-2005.html http://www.nat-hazards-earth-syst-sci.net/5/63/2005/nhess-5-63-2005.pdf 63 69 2005-01-05 Investigation of ULF magnetic anomaly during Izu earthquake swarm and Miyakejima volcano eruption at summer 2000, Japan A. Kotsarenko O. Molchanov M. Hayakawa S. Koshevaya V. Grimalsky R. Pérez Enríquez J. A. López Cruz-Abeyro Centro de Geociencias, Juriquilla, UNAM, Apdo Postal 1-742, Centro Queretaro, Querétaro, C.P. 76001, Mexico Institute of the Physics of the Earth, Moscow, Russia University of Electro Communications, Chofu 1-5-1, Tokyo 182-8585, Japan CIICAp, UAEM, Cuernavaca, Morelos, Mexico INAOE, Tonantzintla, P.O.51&216, C.P. 72000, Puebla, Pue., Mexico Results of the ULF electromagnetic emission during the Izu, 2000 earthquake (EQ) swarm and Miyake volcano eruptions during the summer period of 2000 are presented and analyzed. The analysis of the obtained data has been performed in 3 main directions: traditional statistical analysis, i.e. analysis of time dynamics of spectral density, polarization ratios and their derivatives, Principal Component Analysis, and Fractal Analysis. The statistical characteristics were studied at different frequency sub-bands in a frequency range 10^-3-0.3 Hz. These methods of data processing are described and the obtained results are illustrated and discussed. Some peculiarities of the obtained results such as the rise of the second principal component and the rise of the fractal index can be interpreted as possible short-time precursors.