Dynamical evolution of the community structure of complex earthquake network

TL;DR

This paper studies how the community structure of earthquake networks evolves over time, especially around main shocks, revealing a characteristic pattern in modularity that reflects seismic activity.

Contribution

It introduces an analysis of the temporal evolution of community structure in earthquake networks, highlighting how main shocks influence community merging and modularity behavior.

Findings

Modularity peaks before main shocks and drops sharply at the event.

Main shocks cause communities to merge into larger ones.

Post-shock, modularity gradually recovers to pre-shock levels.

Abstract

Earthquake network is known to be complex in the sense that it is scale-free, small-world, hierarchically organized and assortatively mixed. Here, the time evolution of earthquake network is analyzed around main shocks in the context of the community structure. It is found that the maximum of the modularity measure quantifying existence of communities exhibits a peculiar behavior: its maximum value stays at a large value before a main shock, suddenly drops to a small value at the main shock, and then increases to relax to a large value again relatively slowly. Thus, a main shock absorbs and merges communities to create a larger community, showing how a main shock can be characterized in the complex-network representation of seismicity.