Pyroclastic density current (PDC) deposits, especially small to medium volume events, have low preservation potential at many volcanoes, particularly when unconsolidated or deposited on steep, glaciated slopes. This may lead to an underrepresentation of these events in the eruptive record, and consequently, in hazard management planning; leaving populations on and around the volcanoes unprepared for the threat of these smaller eruptions. Therefore, it is important to investigate and recognize these smaller events in the volcanic record to create more comprehensive plans for future eruptions. Mt. Ruapehu is one of New Zealand’s most active volcanoes, last erupting in 2007. Few studies have investigated the PDC occurrence on this volcano, despite PDCs being one of the most hazardous volcanic processes. Poor preservation of PDC deposits, due to small volume, past glaciations, erosion, burial, and poor consolidation has left a significant gap in Mt. Ruapehu’s eruptive record. By identifying and characterizing PDCs on Mt. Ruapehu this paper provides an updated account of PDC occurrence on this volcano, especially for smaller scale PDCs. Comprehensive field-mapping forms the basis for this study by identifying PDC deposits from partial outcrop exposures. We use field observations of these deposits to describe the lithofacies and infer PDC behavior. Relative stratigraphy and whole-rock geochemistry are used to correlate deposits with dated units from literature and provide approximate age ranges. This study describes 12 PDC deposits representing at least 10 previously unidentified flows. Combined with PDCs identified in previous studies there is a total of 23 PDC deposits found on Mt. Ruapehu, including the PDC observed during the 1945 eruption. These PDCs have been emplaced throughout Mt. Ruapehu’s 250 ka eruptive history. The PDCs were concentrated and dominated by granular flow or granular fluid-based flow transport regimes. The lithofacies show PDCs forming from column collapse and dome collapse or explosion events. This demonstrates that Mt. Ruapehu is capable of producing a spectrum of PDC styles and sizes, something that must be considered during future hazard planning on the volcano.

火山碎屑流（PDC）沉积物，尤其是中小体积事件，在许多火山中具有较低的保存潜力，尤其是当未固结或沉积在陡峭的冰川斜坡上时。这可能导致这些事件在喷发记录中的代表性不足，因此在危害管理计划中的代表性不足；使得火山上和火山周围的居民没有为这些较小喷发的威胁做好准备。因此，重要的是要调查和认识火山记录中的这些小事件，从而为未来的喷发制定更全面的计划。公吨。鲁阿佩胡（Ruapehu）是新西兰最活跃的火山之一，于2007年爆发。尽管PDC是最危险的火山过程之一，但很少有研究调查该火山上的PDC发生。PDC存款保存不善，由于体积小，过去的冰川，侵蚀，埋葬和不良的固结使Mt山脉有很大的缺口。鲁阿佩胡的喷发记录。通过识别和表征山上的PDC。鲁阿佩胡（Ruapehu）本文提供了该火山上PDC发生的最新信息，特别是对于较小规模的PDC。通过从局部露头暴露中识别出PDC沉积物，全面的田间作图为这项研究奠定了基础。我们使用对这些矿床的野外观测来描述岩相和推断PDC行为。相对地层学和全岩地球化学用于将沉积物与文献中注明日期的单元联系起来，并提供近似的年龄范围。这项研究描述了12个PDC矿床，这些矿床至少代表了10个以前未确定的流量。结合先前研究中确定的PDC，在Mt上总共发现了23个PDC矿床。鲁阿佩胡（Ruapehu），包括1945年爆发的PDC。这些PDC已安装在整个Mt. 鲁阿佩胡（Ruapehu）的250 ka爆发史。PDC集中在颗粒流或基于颗粒流体的流传输机制中。岩相显示由柱塌陷和穹顶塌陷或爆炸事件形成的PDC。这表明山。鲁阿佩胡（Ruapehu）能够产生一系列PDC样式和大小，这在火山的未来灾害规划中必须加以考虑。这表明山。鲁阿佩胡（Ruapehu）能够产生一系列PDC样式和大小，这在火山的未来灾害规划中必须加以考虑。这表明山。鲁阿佩胡（Ruapehu）能够产生一系列PDC样式和大小，这在火山的未来灾害规划中必须加以考虑。