Pyroclastic density currents (PDCs) are one of the most dangerous volcanic phenomena. The correct interpretation and mapping of PDC deposits in the volcano record is important to establish the eruptive style and play a fundamental role in hazard assessment and risk management. The Copahue volcano is an active intermediate volcano of the Southern Volcanic Zone of the Andes (Argentina-Chile) that presents fragmentary evidence of explosive activity during its evolution, with unusual minor PDC deposits. The recorded historic eruptions were mainly phreatomagmatic due to the presence of a crater lake. In this study, four key deposits previously interpreted as PDC products corresponding to different stages of the Copahue volcano evolution (Pleistocene, Holocene, and Historic times) are analyzed and this origin is discussed: (i) A Pleistocene reddish succession located in the northeast flank of the volcano formed by stretched bombs in a coherent lava is interpreted as clastogenic lavas; (ii) a series of proximal bedded volcaniclastics deposits of Pleistocene age are interpreted as redeposition of hyaloclastic fragments from syn-eruptive subglacial meltwater flows associated with subglacial eruptions; (iii) a distal Holocene deposit located ~12 km east of the active crater consist mainly in fine-sized clasts forming aggregates is reinterpreted as a sedimentary (lacustrine) deposit with volcaniclastic input; and, (iv) a historic whitish-grey clastic deposit located on the eastern flank is considered a product of a mixed avalanche generated during the 1992–1995 activity. Consequently, the PDC occurrence during the Copahue volcano evolution is less than previously thought. Large PDCs are unlikely in the future and their influence area would be reduced near the active crater as observed in recent eruptions. Flows triggered by the melting of snow/ice during volcanic activity and sudden drainage of the crater lake appear to be a more likely potential hazard that should be considered during risk assessment.

火山碎屑密度流 (PDC) 是最危险的火山现象之一。正确解释和绘制火山记录中的 PDC 沉积物对于确定喷发方式和在灾害评估和风险管理中发挥基础性作用非常重要。Copahue 火山是安第斯山脉（阿根廷-智利）南部火山区的一座活跃的中间火山，在其演化过程中提供了爆炸活动的零碎证据，具有不寻常的少量 PDC 沉积物。由于火山口湖的存在，记录的历史喷发主要是水岩浆喷发。在这项研究中，分析了先前被解释为对应于 Copahue 火山演化不同阶段（更新世、全新世和历史时期）的 PDC 产品的四个关键矿床，并讨论了这一起源：(i) 位于火山东北侧的更新世红色序列由连贯的熔岩中的拉伸炸弹形成，被解释为碎裂熔岩；(ii) 更新世时期的一系列近端层状火山碎屑沉积物被解释为与冰下喷发相关的同步喷发冰下融水流的透明碎屑碎片的再沉积；(iii) 位于活动火山口以东约 12 公里的远端全新世矿床，主要由形成聚集体的细碎碎屑组成，被重新解释为具有火山碎屑输入的沉积（湖相）矿床；(iv) 位于东侧的一个历史悠久的灰白色碎屑矿床被认为是 1992-1995 年活动期间产生的混合雪崩的产物。最后，Copahue 火山演化过程中的 PDC 发生率比以前认为的要少。大型 PDC 未来不太可能出现，它们的影响区域将在最近的火山喷发中观察到的活动火山口附近减少。火山活动期间雪/冰融化和火山口湖的突然排水引发的流动似乎是风险评估期间应考虑的更有可能的潜在危害。