Volatile resorption expedites eruption onset in large silicic systems

Abstract Silicic caldera-forming eruptions are among the most hazardous natural phenomena on Earth, yet their triggering mechanisms remain poorly understood. While volatile exsolution is widely recognized as a potential eruption driver in large silicic systems, we find that volatile resorption can, counterintuitively, promote chamber pressurization faster than volatile exsolution. Using a thermo-mechanical magma chamber model, we show that resorption is a common process in rapidly recharged systems, driven by pressure increase and crystal melting. The Aso-4 eruption offers a natural case where volatile resorption may have occurred, with model results predicting resorption at recharge rates >10 -2.4 km 3 /yr. Through reducing bulk magma compressibility, resorption amplifies pressurization, driving chamber destabilization and potentially expediting eruption onset. Here, we propose that volatile resorption is a natural process both accommodating and promoting rapid chamber pressurization, fundamental to destabilizing large-scale silicic systems. Detecting its signatures in monitoring signals could provide early warning of imminent eruption.