@article{3153696,
    title = "Scale-specific order parameter fluctuations of seismicity before
mainshocks: Natural time and Detrended Fluctuation Analysis",
    author = "Varotsos, P. A. and Sarlis, N. V. and Skordas, E. S.",
    journal = "Europhysics Letters (EPL)",
    year = "2012",
    volume = "99",
    number = "5",
    publisher = "IOP Publishing Ltd",
    doi = "10.1209/0295-5075/99/59001",
    abstract = "The order parameter fluctuations of seismicity are investigated upon
considering a natural time window of fixed length sliding through the
consecutive earthquakes that occurred in California. We previously found
that when this length corresponds to a time period of the order of a few
months, the fluctuations exhibit a global minimum before the strongest
mainshock. Here, we show that in California, during the twenty five year
period 1979-2003, minima of the fluctuations are identified 1 to 5
months before four out of five mainshocks with magnitude M - 7.0 or
larger as well as before the M = 6.9 Northridge earthquake. These minima
are accompanied by minima of the exponent a of the Detrended Fluctuation
Analysis (DFA) of the earthquake magnitude time series, which since
alpha < 0.5 indicate anticorrelated behavior. These results of DFA alone
cannot serve for prediction purposes, but do so when combined with the
aforementioned minima in the fluctuations of the order parameter of
seismicity identified in natural time analysis. Copyright (c) EPLA, 2012"
}