Magma reservoir evolution during the build up to and recovery from caldera-forming eruptions – A generalizable model?

Silicic calderas globally tend to record a cyclic magmatic, structural, and eruptive evolutionary progression. Some are polycyclic, involving multiple catastrophic collapses in the same approximate location. Here we discuss five examples from well-studied, geologically-young active magmatic systems: The Kos-Nisyros Volcanic Complex (Greece), Long Valley (USA), Campi Flegrei (Southern Italy), Rabaul (Papua New Guinea), Okataina (New Zealand) order gain insights on inner workings of caldera systems during build up recovery large explosive eruptions. We show that sub-caldera system evolves through series processes, here collectively termed “caldera cycle”, common monocyclic polycyclic calderas. In case calderas, they accompany transition one caldera-forming eruption next. cycle comprises (1) period pre-collapse activity (incubation, maturation, widespread presence volatile phase), (2) (CCF) eruption, (3) post-collapse (resurgence, renewed eruptions, subsequent maturation) or possible cessation cycle. incubation phase corresponds thermal maturation crust, which eruptions frequent small volume due limited capability reservoirs grow. During phase, magma gradually grow, coalesce, homogenize, magmas differentiate, frequency decreases. transitions into fermentation once an exsolved is continuously present reservoir, thereby increasing compressibility instigating runaway growth reservoir. A CCF at end could be concatenated result processes (including recharge, exsolution, crystal mush remelting) pressurizing while external factors (e.g., tectonic processes) can also play role. Postcaldera subvolcanic intrusions, hydrothermal typically continue, even if supply wanes. If, however, depth remains substantial, may recover, initially erupting remobilized reservoir and/or new recharging until shallow starts grow mature again. Placing other worldwide within this framework would enable test robustness proposed framework, deepen understanding what controls duration its individual phases, refine petrologic, geophysical, unrest symptoms characteristic state system.