On the space-time distribution of major explosive volcanic eruptions on Earth

Explosive volcanic activity on Earth is typically discontinuous in space and time. The occurrence of spatial/temporal eruption clusters due to mutual cause-and-effect relationships or external triggers (e.g., tectonic and/or tidal forcing) is still debated. To detect possible clustering of major explosive eruptions, we test the distribution of eruptions with Volcanic Explosivity Index (VEI) >= 4 from 1750 to present. The 143 documented VEI >= 4 events display a markedly non-uniform frequency distribution, with the highest relative probability of eruption recurrence within 500 km distance from the preceding event. The analogous frequency pattern obtained from randomized data series of the same catalogue suggests that the observed eruption pattern is primarily imparted by the geodynamic distribution of volcanoes (mostly located along tectonically active linear belts), with no evidence of mutual or external influence. Our results highlight a counter-intuitive array of major eruption loci as a consequence of the intrinsic worldwide asymmetry of explosive volcanism, with implications on hazard assessment.