Dynamics of large effusive eruptions driven by caldera collapse

The largest eusive basaltic eruptions are associated with caldera collapse and are manifest 8 through quasi-periodic ground displacements and moderate sized earthquakes[1, 2, 3], yet the 9 mechanism governing their dynamics remains elusive. In this work we provide a new physical 10 model to understand these processes, which accounts for both the quasi-periodic stick-slip 11 collapse of the caldera roof and the long term eruptive behaviour. We show that it is the 12 caldera collapse itself that sustains large eusive eruptions, and that triggering caldera collapse 13 requires, in turn, topography generated pressures. The model is consistent with data for the 14 2018 Kilauea eruption and allows us to estimate for the rst time, the properties of the plumbing 15 system. The results reveal that two reservoirs were active during the eruption and constrain 16 their connectivity. Compared to the model, the Kilauea eruption stopped after producing 17 slightly more than 60% of its potential collapses, possibly due to the presence of the second 18 reservoir. Finally, we show that this physical framework is generally applicable to the largest 19 instrumented caldera collapse eruptions of the past fty years.