Using visual, seismic, SO 2 -gas and thermal infrared data collected over 3 months, we observed systematic variations in the steady-state Strombolian-style activity of Yasur volcano. Observations reveal insights into the relationship between explosion magnitude and style with shallow conduit and magmatic conditions. Powerful eruptive phases are dominated by lava-rich activity, suggesting a high magma and volatile flux from depth that fills hot conduit pathways with mobile magma. Weak eruptive phases produced low-frequency ash-dominated explosions, indicative of cooling and stagnant magma near the top of the conduit and/or a debris layer covering the vent. Statistical forecast modelling was applied to explore if information on the previous days’ activity could forecast the next day and provide insights into multi-vent eruption patterns. Results suggest that North and South crater conduits are separated at significant depths and changes to either crater represent the variable proportions of magma and volatile flux directed into one pathway or the other. Zones A and B within the South crater have an alternating relationship, swapping between periods of active-inactive, or high-low magnitude. This appears to reflect the shallow diversion of magma and volatile flux between each vent, likely due to temporary conduit blockage and clearance cycles. Multiple timescales of eruptive behaviour change were revealed. Approximately 5-day cycles show changes in explosion parameters at individual vent zones, reflecting magma-level fluctuations and convection within the higher levels of each conduit. Cycles 10 to 20 days long occur in overall eruptive activity, and may reflect magma chamber processes that distribute magma and volatile flux differentially between the North and South conduits.

中文翻译：

---

瓦努阿图亚苏尔火山喷发方式、幅度和喷口形态的时空变化：对管道系统的洞察

使用超过 3 个月收集的视觉、地震、SO 2 - 气体和热红外数据，我们观察到 Yasur 火山稳态 Strombolian 型活动的系统变化。观测结果揭示了爆炸强度和类型与浅层管道和岩浆条件之间的关系。强大的喷发阶段以富含熔岩的活动为主，这表明来自深处的高岩浆和挥发性通量用流动的岩浆填充了热通道。弱喷发阶段产生了以灰烬为主的低频爆炸，表明管道顶部附近的冷却和停滞岩浆和/或覆盖通风口的碎片层。应用统计预测模型来探索有关前几天活动的信息是否可以预测第二天并提供对多通风口喷发模式的见解。结果表明，南北陨石坑管道在很深的地方分开，任一陨石坑的变化代表了进入一条通道或另一条通道的岩浆和挥发性通量的不同比例。南陨石坑内的 A 区和 B 区具有交替关系，在活跃-不活跃或高低震级之间交换。这似乎反映了每个喷口之间岩浆和挥发性通量的浅转移，可能是由于暂时的管道堵塞和清除循环。揭示了爆发性行为变化的多个时间尺度。大约 5 天的循环显示了各个通风口区域的爆炸参数的变化，反映了每个管道较高层级内的岩浆水平波动和对流。10 到 20 天的周期发生在整体喷发活动中，