  We inquire the statistical nature and dynamics of shallow and deep
seismogenesis along major plate margins of the NW Circum-Pacific Belt, by
examining whether earthquakes are generated by Poisson processes and are
independent (uncorrelated), or by Complex processes and are dependent
(correlated). Analysis is based of Non Extensive Statistical Physics and the
complete and homogeneous catalogue of the Japan Meteorological Agency for the
period 2002-2016.5. Emphasis is given to background seismicity recovered by
removing aftershocks with stochastic declustering. Long-term correlation and
long-range interaction is mostly weak to moderate in shallow background
seismicity. Conversely, deep seismicity is mostly uncorrelated
(quasi-Poissonian), particularly in Wadati-Benioff zones. As function of time,
shallow background seismicity exhibits persistent weak to moderate correlation;
sub-crustal background seismicity is generally quasi-Poissonian but may
dynamically transition to moderate-significant in association with temporal
clusters of large earthquakes. A universal such effect was observed ahead of
the 2011.19 Tohoku mega-earthquake. These results contrast observations along
the Pacific-North American transformational plate boundaries of California and
Alaska which are generally correlated, suggesting that the geodynamic setting
is essential in the development of self-organization and Complexity. Moreover,
observations appear consistent with simulations of small-world fault networks
in which free boundary conditions at the surface allow for Complexity to
develop, while fixed boundary conditions at depth do not.
