| Natural time [1-6] can reveal novel dynamical features hidden behind the time series of
complex systems, for a review see Ref.[7]. In a time series comprising N earthquakes, the
natural time Ïk = k-N serves as an index for the occurrence of the k-th event[1, 5, 6], and is
smaller than or equal to unity. In natural time analysis of seismicity, the evolution of the pair
of two quantities (Ïk, Ek) is considered, where Ek denotes the energy emitted
during the k-th earthquake. It has been proposed[5] that the variance κ1 of natural
time can play the role of an order parameter for seismicity. Moreover, when using
natural time the identification of temporal correlations -even in the presence of
heavy tails in the data- becomes possible[6]. Thus, natural time analysis enables the
identification of magnitude correlations between successive earthquakes[8]. By analyzing in
natural time[9] the worldwide seismicity from the Harvard Global Centroid Moment
Tensor Catalog as reported by the United States Geological Survey as well as the
most recent version (1900-2007) of the Centennial earthquake Catalog[10], we find
non-trivial magnitude correlations for earthquakes of magnitude greater than or equal to
7.
REFERENCES
[1] P. A. Varotsos, N. V. Sarlis, and E. S. Skordas, Practica of Athens Academy 76, 294
(2001).
[2] P. A. Varotsos, N. V. Sarlis, and E. S. Skordas, Phys. Rev. E 66, 011902
(2002).
[3] P. A. Varotsos, N. V. Sarlis, and E. S. Skordas, Phys. Rev. E 67, 021109
(2003).
[4] P. A. Varotsos, N. V. Sarlis, and E. S. Skordas, Phys. Rev. E 68, 031106
(2003).
[5] P. A. Varotsos, N. V. Sarlis, H. K. Tanaka, and E. S. Skordas, Phys. Rev. E 72, 041103
(2005).
[6] P. Varotsos, N. Sarlis, E. Skordas, and M. Lazaridou, Phys. Rev. E 74, 021123
(2006).
[7] P. A. Varotsos, N. V. Sarlis, and E. S. Skordas, NATURAL TIME ANALYSIS: THE
NEW VIEW OF TIME. Precursory Seismic Electric Signals, Earthquakes and other Complex
Time Series, Springer-Verlag, Berlin Heidelberg (2011).
[8] N.V. Sarlis, E.S. Skordas and P.A. Varotsos, Phys. Rev. E 80 022102 (2009).
[9] N. V. Sarlis, Phys. Rev. E 84, 022101 (2011),.
[10] E. R. Engdahl and A. Villaseñor, 2002. Global seismicity: 1900-1999. In:
Lee, W. H. K., Kanamori, H., Jennings, P. C., Kisslinger, C. (Eds.), International
Handbook of Earthquake and Engineering Seismology, Part A, Chapter 41. Vol.
81A of International Geophysics Series. Academic Press, London, pp. 665–690. |