The relationships between large tectonic earthquakes and explosive volcanic eruptions

Abstract:

Volcanoes and earthquakes are spatially correlated, primarily occurring in plate boundary regions and most prevalently at subduction zones. Temporal correlations between volcanic eruptions and large (non-volcanic) earthquakes have also been suggested, but the underlying mechanism is less clear. Such a correlation may be expected due to either interactions between earthquakes and volcanoes, or due to temporal variations in the underlying tectonic controls. We perform statistical analyses on 1960-2019 global earthquake and eruption datasets to study both long-term correlations between earthquake and eruption rates and shorter-term triggering of eruptions by earthquakes. We investigate how earthquake parameters including magnitude, source depth, and earthquake mechanism affect the eruption triggering tendency. Monte Carlo simulations using randomised earthquake and eruption dates constrain the statistical significance of the results and account for long-term biases in the records. We also use this statistical framework to re-examine the effects of the time and distance between earthquakes and eruptions, declustering of aftershocks, and VEI. At the long-term global scale, we provide evidence for a correlation between earthquake and eruption rates (e.g. both decreasing since the early 2010’s). For shorter-term eruption triggering, we find that potentially triggered volcanic eruptions occur almost exclusively at arc volcanoes and that earthquake depth and mechanism can affect the triggering tendency; specifically, deeper hypocentres and normal faulting styles promote enhanced eruption triggering. Ongoing work is exploring causative explanations for the temporal relationships between earthquakes and eruptions (e.g. coulomb stress modelling of how earthquakes affect magma pathways). The results have implications for understanding of geohazards and tectonomagmatic processes.