Study of the temporal correlations in the magnitude time series before major earthquakes in Japan

Abstract

A characteristic change of seismicity has been recently uncovered when the precursory Seismic Electric Signals activities initiate before an earthquake occurrence. In particular, the fluctuations of the order parameter of seismicity exhibit a simultaneous distinct minimum upon analyzing the seismic catalog in a new time domain termed natural time and employing a sliding natural time window comprising a number of events that would occur in a few months. Here we focus on the minima preceding all earthquakes of magnitude 8 (and 9) class that occurred in Japanese area from 1 January 1984 to 11 March 2011 (the day of the M9 Tohoku earthquake). By applying Detrended Fluctuation Analysis to the earthquake magnitude time series, we find that each of these minima is preceded as well as followed by characteristic changes of temporal correlations between earthquake magnitudes. In particular, we identify the following three main features. The minima are observed during periods when long-range correlations have been developed, but they are preceded by a stage in which an evident anticorrelated behavior appears. After the minima, the long-range correlations breakdown to an almost random behavior possibly turning to anticorrelation. The minima that precede M ≥ 7.8 earthquakes are distinguished from other minima which are either nonprecursory or followed by smaller earthquakes. Furthermore, it is discussed whether Tsallis statistical mechanics, in the frame of which it has been suggested that kappa distributions arise, can capture the effects of temporal correlations between earthquake magnitudes.

Identifying the occurrence time of an impending major earthquake: a review

“…It is worthwhile to notice that before using the minimum of the fluctuations of seismicity to deduce the epicentral area of the impending mainshock, it is a prerequisite to ascertain that this minimum is truly a precursory one of a major earthquake by applying the criteria that distinguish the non-precursory minima from the precursory ones as described in ''Appendix'' of Varotsos et al (2014) (see also Sarlis et al 2016).…”

M W9 Tohoku earthquake in 2011 in Japan: precursors uncovered by natural time analysis

“…Along these lines, Varotsos et al (2014) Uyeda et al (2002Uyeda et al ( , 2009). In addition, Varotsos et al (2014) increased the magnitude threshold from M JMA = 3.4 to M JMA = 3.5 to assure a more safe data completeness. Setting this threshold, and considering the period from January 1, 1984, to March 11, 2011 (the date of M W 9 Tohoku earthquake), we are left with 47,204 EQs and 41,277 earthquakes in the concerned period of about 326 months in the larger (black rectangle) and smaller (yellow rectangle) area, respectively.…”

“…Let us now investigate here whether this criterion is obeyed in the aforementioned case studied by Varotsos et al (2013). Along these lines, Varotsos et al (2014) Uyeda et al (2002Uyeda et al ( , 2009). In addition, Varotsos et al (2014) increased the magnitude threshold from M JMA = 3.4 to M JMA = 3.5 to assure a more safe data completeness.…”

“…In a later study (Varotsos et al 2014), a set of criteria has been developed to distinguish truly precursory minima b W,min of the order parameter of seismicity from non-precursory ones. One of these criteria demands that a truly precursory minimum b W,min should exhibit spatial invariance in the following sense: It should appear almost on the same date (within the aforementioned experimental error of course) when changing the boundaries of the area studied.…”

Earthquake source parameters that display the first digit phenomenon

“…Since 2004, three of these spectacular events have occurred, each producing large tsunamis, followed by human and material losses. These are the 2004 Northern Sumatra (Lay et al, 2005), the 2010 Central Chile (Vigny et al, 2011) and the 2011 Tohoku, Japan (Simons et al, 2011), earthquakes, each of them representing an opportunity to advance in the comprehension of geophysical phenomena. Three key elements in the understanding of these events are (a) the source process, a highly nonlinear and heterogeneous phenomenon regarding the initiation, growth and stopping of the earthquake itself, (b) the postseismic relaxation effects, which comprise the later perturbations at the crust and fault itself after the stop of the slip phase, and (c) the water wave produced by the sudden uplift of the ocean floor, its propagation through the ocean and the, often destructive, arrival inland.…”