Earthquakes unveil the global-scale fractality of the lithosphere

The relationship between the magnitude of earthquakes and their spatial and temporal distribution has been observed to exhibit a scale invariance hypothesised to originate from selforganized critical regimes. However, the fractality of earthquake distributions has been mostly established in circumscribed areas, despite the fact that the self-organized criticality of the lithosphere should only emerge at global or continental level. Here, we analyze seismic observations occurring over the whole Earth between 2004–2020 to investigate the fractal correlation dimension of earthquakes distribution. We find that the distribution of earthquakes is fractal on a global scale, as well as approximately magnitude-independent and stationary over decadal time scales. Our results set a primary constraint on the spatial scaling properties of lithosphere dynamics. We suggest that macroscopic models should fulfil this constraint to correctly replicate the features of seismicity, and potentially improve seismic hazard assessment.