How far away is the next earthquake?

TL;DR

This paper analyzes the spatial and temporal patterns of earthquakes in southern California, revealing scale-free statistics and independence of spatial distances from magnitude thresholds, challenging existing aftershock zone theories.

Contribution

It uncovers that earthquake distances follow scale-free distributions independent of magnitude, and that spatial and temporal aspects are uncorrelated, contradicting traditional aftershock models.

Findings

Spatial distances exhibit scale-free statistics with exponent ~0.6.

Distances are independent of magnitude thresholds in complete catalogs.

Spatial and waiting times are uncorrelated.

Abstract

Spatial distances between subsequent earthquakes in southern California exhibit scale-free statistics, with a critical exponent $\delta \approx 0.6$, as well as finite size scaling. The statistics are independent of the threshold magnitude as long as the catalog is complete, but depend strongly on the temporal ordering of events, rather than the geometry of the spatial epicenter distribution. Nevertheless, the spatial distance and waiting time between subsequent earthquakes are uncorrelated with each other. These observations contradict the theory of aftershock zone scaling with main shock magnitude.