Potrerillo I, Potrerillo II, and San Juanito volcanoes are part of the 28 Late Quaternary monogenetic eruptive vents concentrated along a ~2-km-wide and ~30-km-long stripe in the vicinity of Ceboruco stratovolcano (western Mexican Volcanic Belt). The studied volcanoes are closely spaced and located within a ~12 km² sub-drainage basin, northwest of Ceboruco's edifice. Eruptive dynamics were inferred from sedimentary, stratigraphic, and pyroclast characteristics. Unlike Potrerillo I, which was formed by an entirely dry explosive magmatic eruption, evidence for the prevalence of initial short-lived phreatomagmatic phases was found for the Potrerillo II and the San Juanito eruptions that ended effusively.

In this study we examine the nature and proportion of different types of pyroclasts within the exposed deposits of these three volcanoes, as well as their sedimentary features to better understand the initiation and progression of their eruptions. Our results indicate that both Potrerillo II and San Juanito tephra ring deposits show dominantly atypical, crudely bedded, coarse-grained deposits where the evidence for energetic, diluted pyroclastic density currents is scarce or subordinated. Instead, low energy, shallow seated, phreatomagmatic explosions generated medium-to-coarse grain-sized pyroclasts that were transported within dense tephra jets that were ballistically ejected, which on deposition formed non-turbulent currents with non-extensive lateral movement. The nature of such eruptive style was controlled by the substrate hydrogeology conditions that prevailed at the time of the eruption. So, magmas of different composition (dacitic for Potrerillo II, and basaltic andesite for San Juanito) followed similar dynamics when interacting with water. We propose that fractured aquifers with shallow water tables (or even surface water) existed at the time of both eruptions and interacted explosively with the magmas.

In contrast, the construction of Potrerillo I scoria cone, which is related exclusively to explosive magmatic activity, does not show evidence of phreatomagmatic activity. This eruption may have occurred when the water table was deep, or surface water was unavailable. The variations in the depth of phreatomagmatic explosions, the availability of the water involved in the phreatomagmatic phases, and the absence or presence of these phases in the studied volcanoes were probably strongly influenced by the water-bearing conditions of the aquifers at the time of the eruption, which in turn, depended on the amount and distribution of annual rainfall.

This study improves our understanding of phreatomagmatic eruptions of diverse magmatic compositions in similar settings. The recognition of associated hazards will allow to further define eruptive scenarios of monogenetic eruptions and help update the volcanic hazard map of the Ceboruco volcano area in the future.

Potrerillo I，Potrerillo II和San Juanito火山是Ceboruco stratovolcano（墨西哥西部火山带）附近约2公里宽和约30公里长的条带中集中的28个第四纪晚期单基因喷发性喷口的一部分。所研究的火山分布紧密，位于Ceboruco大厦西北约12 km ²的分流盆地内。从沉积，地层和火山碎屑特征推断出爆发动力学。与由完全干燥的爆炸性岩浆喷发形成的波特里洛一世不同，发现了波托里洛二世和圣胡安尼托爆发的最初短暂的吞噬岩浆期普遍存在的证据，但这些喷发均以有效的方式结束了。

在这项研究中，我们检查了这三座火山暴露的沉积物中不同类型的火山碎屑的性质和比例，以及它们的沉积特征，以更好地了解其爆发的发生和发展。我们的结果表明，Potrerillo II和圣胡安尼托特非拉环型矿床均显示出主要为非典型，粗层状，粗粒状矿床，其中缺乏活力或稀有的火成碎屑密度流的证据。取而代之的是，低能浅坐位的岩浆爆裂产生了中等至粗大的颗粒状火山碎屑，这些火山碎屑在被弹道喷射的密集的提夫拉喷气流中运输，在沉积过程中形成了非湍流且横向运动不大。这种喷发方式的性质由喷发时普遍存在的基质水文地质条件控制。因此，与水相互作用时，不同成分的岩浆（波特拉利奥二世为大岩浆，圣胡安尼托为玄武安山岩）具有相似的动力学。我们建议在两次喷发时都存在浅水位（甚至地表水）的裂隙含水层，并与岩浆爆发性地相互作用。

相反，仅与爆炸性岩浆活动有关的Potrerillo I火山灰锥的构造并未显示出岩浆岩活动的证据。当地下水位较深或没有地表水时，可能​​会发生这种喷发。喷发岩浆爆炸深度的变化，喷发岩浆相中所含的水的可用性以及研究火山中这些相的不存在与否可能受到当时含水层含水状况的强烈影响。喷发又取决于年降雨量的数量和分布。

这项研究提高了我们对相似​​环境中多种岩浆成分的岩浆喷发的认识。对相关危害的认识将有助于进一步定义单基因喷发的喷发情景，并有助于将来更新Ceboruco火山区的火山危害图。