Fractal analysis for the ULF data during the 1993 Guam earthquake to study prefracture criticality

Abstract. An extremely large earthquake (with magnitude of 8.2) happened on 8 August 1993 near the Guam island, and ultra-low-frequency (ULF) (frequency less than 1 Hz) electromagnetic fields were measured by 3-axis induction magnetometers at an observing station (with the epicentral distance of 65 km) with sampling frequency of 1 Hz. In order to study electromagnetic signature of prefracture criticality, we have undertaken the fractal (mono-fractal) analysis by means of the Higuchi's method for the ULF data during the 1993 Guam earthquake. Then, it is found that the fractal dimension exhibits five maxima 99, 75, 52, 21, and 9–4 days before the earthquake main shock, which suggests the ULF electromagnetic signature of nonlinear evolution (in the sense of self-organized criticality) taking place in the lithosphere just before the 1993 large Guam earthquake. That is, there take place step-like changes in the lithosphere during the long-term of the order of several months before the main shock.

[1]  Masashi Hayakawa,et al.  Fractal analysis of ULF geomagnetic data associated with the Guam Earthquake on August 8, 1993 , 1999 .

[2]  M. Hayakawa,et al.  Summary report of NASDA's earthquake remote sensing frontier project , 2004 .

[3]  L. Burlaga,et al.  Fractal structure of the interplanetary magnetic field , 1986 .

[4]  Observation of ULF (Ultra-Low-Frequency) electromagnetic emissions associated with earthquakes , 2004, Proceedings of 2nd International Conference on Recent Advances in Space Technologies, 2005. RAST 2005..

[5]  P. Bliokh.  Atmospheric and Ionospheric Electromagnetic Phenomena Associated with Earthquakes: M. Hayakawa. 1999, 996 + xx pp, Terra Scientific Publishing Tokyo, US $140.00 (hb), ISBN: 4-88704-124-1 , 2000 .

[6]  早川 正士,et al.  Electromagnetic phenomena related to earthquake prediction , 1994 .

[7]  M. Hayakawa,et al.  Fractal analysis of the ULF geomagnetic data obtained at Izu Peninsula, Japan in relation to the nearby earthquake swarm of June–August 2000 , 2003 .

[8]  M. Hayakawa,et al.  Scaling characteristics of ULF geomagnetic fields at the Guam seismoactive area and their dynamics in relation to the earthquake , 2001 .

[9]  Kiyohumi Yumoto,et al.  Results of ultra-low-frequency magnetic field measurements during the Guam Earthquake of 8 August 1993 , 1996 .

[10]  M. Hayakawa,et al.  On the generation mechanism of ULF seismogenic electromagnetic emissions , 1998 .

[11]  早川 正士,et al.  Seismo electromagnetics : lithosphere-atmosphere-ionosphere coupling , 2002 .

[12]  Masashi Hayakawa,et al.  Fractal analysis of seismogenic ULF emissions , 2004 .