More than half of explosive volcanic eruptions contain multiple eruption phases with eruption dynamics (i.e., style, intensity, magnitude) varying with eruption progression. While probabilistic eruption forecast models constitute a useful tool for decision making during volcanic crises, the probabilistic forecast of likelihood, style and magnitude of potentially upcoming phase(s) within a multi-phase eruption progression remains a major challenge. Probabilistic eruption forecast models are crucially dependent on the quality of the underlying eruption records and their ability to account for inter-sequence and intra-sequence changes in eruption behaviour. Recent studies examining multi-phase eruption progression have been limited by the amount of historical data available, motivating the investigation into the feasibility of identifying and quantifying multi-phase eruption behaviour in the geological record. Mt. Ruapehu is one of New Zealand's most active volcanoes and its 1800 years-present Tufa Trig Formation comprises at least thirty-one small to moderate explosive eruptions, of which more than half contain more than one phase. An interpolated age model for the past 1800 years is presented and used to model inter-sequence eruption onsets. Four volcanic regimes, distinguished by eruption frequency and magnitude can be identified: (1) A low rate regime with an average of one eruption every 125 years, involving mostly single-phase low to mid-intensity eruptions, (2) two medium rate regimes with a 40 year average recurrence interval and (3) a high frequency regime characterised by decadal-scale reposes, and including the largest multi-phase eruptions of the past 1800 years. Tephra volume estimates are combined with a statistical model for the number of phases to characterise the intra-sequence progression. Eruption progression is consistent with existing multi-phase models developed on historical data, and suggests that tephra volume increases in later phases of an eruption.

超过一半的火山爆发包含多个喷发阶段，其喷发动力学（即样式，强度，大小）随喷发进程而变化。尽管概率喷发预测模型是火山危机期间决策的有用工具，但是对多阶段喷发进展中潜在即将发生的相的可能性，样式和大小的概率预测仍然是一个重大挑战。概率喷发预测模型主要取决于基本喷发记录的质量及其对喷发行为的序列间和序列内变化进行解释的能力。最近研究多相喷发进展的研究受到可用历史数据的限制，促使人们研究确定和量化地质记录中多相喷发行为的可行性。公吨。鲁阿佩胡（Ruapehu）是新西兰最活跃的火山之一，其拥有1800年历史的Tufa Trig地层包括至少31个小至中度的爆发喷发，其中一半以上包含一个以上的相。提出了过去1800年的插值年龄模型，并将其用于对序列间爆发的发作进行建模。可以确定四种以火山喷发频率和震级区分的火山状态：（1）一种低速火山区，平均每125年喷发一次，主要涉及单相中低强度喷发；（2）两种中等火山速区具有40年的平均复发间隔，以及（3）以年代规模休止为特征的高频治疗方案，包括过去1800年中最大的多相爆发。Tephra体积估计值与统计模型相结合，以表征序列内进程。爆发过程与基于历史数据开发的现有多相模型相一致，并表明在爆发的后期阶段，特菲拉的数量会增加。