Evaluating steady-state volcanism in Iceland, La Réunion, Hawaiʻi and western Galápagos: connections with volcanic hazards and future perspectives

Steady-state volcanoes and magmatic provinces erupt magmas at nearly constant rates over the course of decades. Here, we analyzed the reliability of steady-state volcanism and its relationship with volcanic hazard evaluation in terms of forecasting the erupted volume at four frequently erupting oceanic hotspots: Iceland, La Réunion, Hawai‘i, and western Galápagos. Over decadal timespans, these hotspots show steady-state activity often characterized by shorter-term cycles with an initial decrease in eruption rates, followed by an increase that rebalances the erupted volumes with the expected ones, providing a rough estimation of the maximum expected erupted volume of these paroxysmal periods. Although rarer, we also observe the opposite behaviour, with the eruption of more magma than expected, followed by low-rate periods proportional to the excess erupted volume. Steadystate rates can change over time, and future studies should investigate if these changes are related to longer-term episodes.