We have coupled three independent methods to investigate the time evolution of eruptive intensity during the sub-Plinian and Plinian phases of the 3600-year BP Late Bronze-Age eruption of Santorini Volcano: (1) mass eruption rate based on new lithic isopleth maps for multiple layers of the fall deposit, (2) magma decompression rate calculated from vesicle number densities, and (3) magma decompression rate calculated from H₂O gradients in melt reentrants, with methods 2 and 3 measured on the same suite of pyroclasts. Mass eruption rate increased by two orders of magnitude, reaching 210 × 10⁶ kg s⁻¹ at the peak of the Plinian phase (plume height 28.4 ± 1.0 km); it then declined in the final stage of fallout emplacement following the first generation of pyroclastic surges. Decompression rates from melt reentrants (0.008 to 0.25 MPa s⁻¹) are two to three orders of magnitude lower than those from vesicle number densities, assuming heterogeneous vesicle nucleation (2 to 19 MPa s⁻¹). Melt reentrants are thought to record slow decompression in the deep feeder conduit, whereas vesicles record much higher rates of decompression in the shallow conduit due to the steep, nonlinear pressure gradients associated with magma vesiculation and fragmentation. Upwardly converging flow from a dike-like, deep conduit to a more cylindrical, shallow conduit may also have played a role in causing upwardly accelerating flow. Variations in deep decompression rate recorded by melt reentrants are decoupled from mass eruption rate, whereas those recorded by vesicles lie in between. Taken with the transition from unsteady to steady Plinian eruption, this may reflect the existence of transient flow conditions in the conduit system due to widening and lengthening of a deep feeder dike as Plinian eruption progressed. As the mass eruption rate rose to its peak value, the fragmentation level fell in the conduit due to increasing rates of magma strain and decompression.

我们已经结合了三种独立的方法来研究圣托里尼火山3600年BP晚青铜时代喷发的亚次普林期和普林期的喷发强度的时间演变：（1）基于新的岩性等值线图的质量喷发率多层秋季沉积物，（2）根据囊泡数密度计算的岩浆减压速率，和（3）根据熔体折返体中的H ₂ O梯度计算的岩浆减压速率，其中方法2和3在同一套破火山岩上进行了测量。喷发率增加了两个数量级，达到210×10 ⁶ kg s ^-1在Plinian相的峰顶（泡沫高度28.4±1.0 km）; 然后在第一代火山碎屑浪潮之后，在尘埃落入的最后阶段下降。假设非均相囊泡成核（2至19 MPa s ^-1），则来自熔体折返（0.008至0.25 MPa s ^-1）的减压速率比囊泡数密度的减压速率低2至3个数量级。）。熔体折返被认为在深层供料管道中记录了缓慢的减压，而由于与岩浆囊化和破碎相关的陡峭，非线性的压力梯度，囊泡在浅层导管中记录了更高的减压速率。从堤坝状的深管道向上汇聚到更圆柱形的浅管道的向上汇流也可能起到了导致向上加速流动的作用。熔体折返记录的深层减压速率的变化与喷发速率脱钩，而囊泡记录的深度介于两者之间。从不稳定的Plinian喷发过渡到稳定的Plinian喷发，这可能反映了管道系统中瞬态流动条件的存在，这是由于随着Plinian喷发的进行，深水馈线堤坝的加宽和加长。