A global statistical study on the triggering of volcanic eruptions by large tectonic earthquakes

Recent studies have shown that large tectonic earthquakes are capable of triggering volcanic eruptions (i.e. increasing the number of eruptions within a defined time period) up to hundreds of kilometres away. However, the prevalence of eruption triggering is less clear, with findings ranging from little evidence for triggered eruptions, to a fourfold increase in the number of eruptions following nearby large earthquakes. Some of this variability is likely due to differences in definitions of what constitutes a triggered volcanic eruption, including a lack of consensus on the maximum distance and time lag between an earthquake and a triggered volcanic eruption, the minimum magnitude of earthquake considered, and how aftershocks are incorporated into the analysis. A further source of variability arises from the different datasets used, including regional versus global studies, and the inclusion of incomplete earthquake and eruption records from before the modern instrumental era. To help address these issues, we provide a comprehensive statistical study of how large earthquakes affect volcanic eruption rates, using complete and unbiased global datasets spanning 1960-2021. We take a systematic approach to investigating how parameters such as the maximum distance and time lag between earthquake-eruption pairs, the minimum earthquake magnitude considered, and the declustering of aftershocks affects the results. We also investigate how previously unstudied earthquake parameters such as source depth and mechanism affect the prevalence of eruption triggering. Our results are placed in statistical context through the use of Monte Carlo simulations using randomised earthquake and eruption catalogues. Preliminary results indicate that, contrary to a previous focus on large subduction megathrust earthquakes, deep normal faulting earthquakes have the greatest eruption triggering tendency. However, when compared with randomised earthquake and eruption catalogues, the overall statistical significance of observed eruption triggering is fairly low.