Materials of the International Conference
50th Anniversary of the International Geophysical Year
and Electronic Geophysical Year

16-19 September 2007 • Suzdal, Russia

Using of modern seismological data to reveal the earthquake precursors

G. A. Sobolev and A. A. Lyubushin

Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia

Abstract

Records obtained at the IRIS world-wide system of broadband seismic stations before strong earthquakes were investigated with a purposes of detecting hidden periodicities, multiple coherence effects and seeking for asymmetric impulses within a minute range of periods. The stations are disposed at different distances from the epicenters of earthquakes. The initial realizations consisted of discrete measurements with a sampling rate of 20 Hz and whole volume of analyzed data exceeded 25 Gb. We used the various programs of processing and analysis of time series: revealing of hidden periodicities in the sequences of peak values at a given level; wavelet analysis of microseisms flow; search for multiple coherence effects based on Fourier and wavelet approaches; estimates of spectral coherence measures evolution of variations of multi-fractal singularity indexes and others. Asymmetric pulses about 3–10 min long did arose several days before the Kronotski 5 December 1997 (M = 7.8), Neftegorsk 27 May 1995 (M = 7.0) and Hokkaido 25 September 2003 (M = 8.5) earthquakes. Intervals of a stable manifestation of several periods (tens of minutes) of pulses were found before the Kronotski and Hokkaido events. Synchronization of microseismic oscillations on different stations was detected starting several days before Hokkaido and Sumatra 26 December 2004 (M = 9.2) earthquakes. Comparison of records obtained on different stations allows estimating the regional and local peculiarities of the anomalies. It is assumed that the nature of these phenomena is related to self-organization properties of the seismic process. The periodic vibrations, asymmetric pulses and synchronization intervals are indicators of the unstable state of a seismically active region and could be regarded as earthquake precursors.

Citation: G. A. Sobolev and A. A. Lyubushin (2007), Using of modern seismological data to reveal the earthquake precursors, in: Materials of the International Conference '50th Anniversary of the International Geophysical Year and Electronic Geophysical Year', GC RAS, Moscow, doi:10.2205/2007-IGY50conf.

© 2007 Geophysical Center RAS and authors


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