Earthquake networks based on similar activity patterns

Abstract

Earthquakes are a complex spatiotemporal phenomenon, the underlying mechanism for which is still not fully understood despite decades of research and analysis. We propose and develop a network approach to earthquake events. In this network, a node represents a spatial location while a link between two nodes represents similar activity patterns in the two different locations. The strength of a link is proportional to the strength of the cross correlation in activities of two nodes joined by the link. We apply our network approach to a Japanese earthquake catalog spanning the 14-year period 1985-1998. We find strong links representing large correlations between patterns in locations separated by more than 1000 kilometers, corroborating prior observations that earthquake interactions have no characteristic length scale. We find network characteristics not attributable to chance alone, including a large number of network links, high node assortativity, and strong stability over time.

Assortative and disassortative mixing investigated using the spectra of graphs

“…assortativity. This property has been increasingly realized as a characteristic of a system [54][55][56]. Our analysis is another demonstration of the importance of spacing analysis in understanding impact of degree-degree correlation on the network detected through the spectra as for very minute changes in r, there are no visible changes in the spectral density, but this leads to a very drastic changes in the eigenvalues fluctuations demonstrating the impact of r values on randomness in a network.…”

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

“…We considered all the EQs in the period from 1984 until the Tohoku EQ occurrence on 11 March 2011, within the area 25°N–46°N, 125°E–148°E shown by the black rectangle in Figure . The eastern edge of this area has been extended by 2° to the east compared to the area 25°N–46°N, 125°E–146°E (yellow rectangle in Figure ) studied by Varotsos et al [] for two reasons: First, when plotting in Figure , the links along with the corresponding nodes recently identified by a network approach developed by Tenenbaum et al [], we see that the nodes in the uppermost right part are now surrounded by the black rectangle but not by the yellow one (cf. a node represents a spatial location while a link between two nodes represents similar seismic activity patterns in the two different locations [ Tenenbaum et al , ]).…”

“…Figure 1) studied by Varotsos et al [2013] for two reasons: First, when plotting in Figure 1, the links along with the corresponding nodes recently identified by a network approach developed by Tenenbaum et al [2012], we see that the nodes in the uppermost right part are now surrounded by the black rectangle but not by the yellow one (cf. a node represents a spatial location while a link between two nodes represents similar seismic activity patterns in the two different locations [Tenenbaum et al, 2012]). Second, the epicenter of the major EQ of magnitude 8.2 that occurred on 4 October 1994 lies inside the former rectangle, but not in the latter (Table 1).…”

“…The small yellow square indicates the location of the Niijima Island where the precursory SES activity of the volcanic‐seismic swarm activity in 2000 in the Izu Island region has been recorded [ Uyeda et al , ]. Furthermore, the network links as reported by Tenenbaum et al [] (see their Figure a) are also shown.…”

Statistical Significance of Minimum of the Order Parameter Fluctuations of Seismicity Before Major Earthquakes in Japan

“…Earthquakes (EQs) exhibit complex correlations in time, space and magnitude (Telesca et al, 2002;Eichner et al, 2007;Huang, 2008Huang, , 2011Telesca, 2010;Lippiello et al, 2009Lippiello et al, , 2012Lennartz et al, 2008Lennartz et al, , 2011Sarlis, 2011;Rundle et al, 2012;Tenenbaum et al, 2012;Sarlis and Christopoulos, 2012). The EQ scaling laws (Turcotte, 1997) point to the view (e.g., Holliday et al, 2006) that a mainshock occurrence may be considered as an approach to a critical point.…”