Dynamics of large effusive eruptions driven by caldera collapse

The largest effusive basaltic eruptions are associated with caldera collapse and are
manifest through quasi-periodic ground displacements and moderate-size
earthquakes1–3, but the mechanism that governs their dynamics remains unclear. Here
we provide a physical model that explains these processes, which accounts for both
the quasi-periodic stick–slip collapse of the caldera roof and the long-term eruptive
behaviour of the volcano. We show that it is the caldera collapse itself that sustains
large effusive eruptions, and that triggering caldera collapse requires
topography-generated pressures. The model is consistent with data from the 2018
Kīlauea eruption and allows us to estimate the properties of the plumbing system of
the volcano. The results reveal that two reservoirs were active during the eruption,
and place constraints on their connectivity. According to the model, the Kīlauea
eruption stopped after slightly more than 60 per cent of its potential caldera collapse
events, possibly owing to the presence of the second reservoir. Finally, we show that
this physical framework is generally applicable to the largest instrumented caldera
collapse eruptions of the past fifty years.