On Venus, relatively young deposits near volcanic and coronal summits with unique radar characteristics have been proposed to be emplaced by pyroclastic density currents (PDCs). The proposed units are laterally extensive, long-runout deposits showing moderate to high radar backscatter and circular polarization ratio in 12.6 cm wavelength synthetic aperture radar data. Previous studies have hypothesized that a recent resumption of volcanic activity in the form of PDC-forming eruptions could have emplaced these deposits. We model the dynamics of dense PDCs using a 2D, depth-averaged framework focusing on regions where stereo-derived topography coverage is available; this includes the flanks of Irnini Mons, Anala Mons, Didilia Corona, and Pavlova Corona. Two different mechanisms of initiation which includes impulsive collapse of an eruption column and sustained pyroclastic fountaining are considered. The results emphasize the importance of pyroclastic flow fluidization via high pore pressure in emplacing long-runout deposits along gently sloping (<2°) volcanic flanks. We also show that collapse of columns >1.2–1.4 km tall as well as pyroclastic fountains lasting >400 s with fountain heights of 50 m are capable of generating pyroclastic flows that could emplace some of the smaller deposits studied. For the large deposits at Irnini Mons, more energetic flows resulting from taller column heights would be necessary; the dynamics of such flows under Venus's conditions are not well understood. Distinguishing between the two initiation styles, that is, column collapse and sustained fountaining is not feasible with currently available datasets and would require higher resolution imagery and topography data.

中文翻译：

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金星密集火山碎屑流动力学建模：对火山碎屑喷发的洞察

在金星上，火山碎屑密度流（PDCs）附近具有独特雷达特征的火山和日冕顶峰附近相对年轻的沉积物已被提出。提议的单元是横向广泛的、长跳动的沉积物，在 12.6 厘米波长合成孔径雷达数据中显示出中到高的雷达反向散射和圆极化比。先前的研究假设，最近以形成 PDC 的喷发形式恢复的火山活动可能已经占据了这些沉积物。我们使用二维深度平均框架对密集 PDC 的动态进行建模，重点关注立体派生地形覆盖可用的区域；这包括 Irnini Mons、Anala Mons、Didilia Corona 和 Pavlova Corona 的侧翼。考虑了两种不同的引发机制，包括喷发柱的脉冲坍塌和持续的火山碎屑喷泉。结果强调了火山碎屑流流化通过高孔隙压力在沿缓坡 (<2°) 火山侧翼包围长径流沉积物的重要性。我们还表明，> 1.2-1.4 km 高的柱子的倒塌以及持续时间 > 400 s 且喷泉高度为 50 m 的火山碎屑喷泉能够产生火山碎屑流，这些流动可以覆盖一些研究的较小沉积物。对于 Irnini Mons 的大型矿床，需要更高的柱高产生更多的能量流动；金星条件下这种流动的动力学尚不清楚。区分两种启动方式，即