Eruption at basaltic calderas forecast by magma flow rate.

Forecasting eruption is the ultimate challenge for volcanology. While there has been some success in forecasting eruptions hours to days beforehand, reliable forecasting on a longer timescale remains elusive. Here we show that magma inflow rate, derived from surface deformation, is an indicator of the probability of magma transfer towards the surface, and thus eruption, for basaltic calderas. Inflow rates ≥0.1 km3 yr−1 promote magma propagation and eruption within 1 year in all assessed case studies, whereas rates.