Sangay is one of the most active volcanoes in the world. Its eruptions were first recorded by Spanish priests in 1628, and since 2010 it has displayed VEI 1–2 level eruptive activity about every two years. Its most recent eruptive phase began on May 7, 2019, and has continued until the present. While most eruptive products do not impact inhabited areas, Sangay's associated Pleistocene-age avalanche deposits were enormous and far-reaching. Their surfaces are now populated by numerous communities on the volcano's E and SE aprons. The study of Sangay's debris-avalanche deposits located in SE Ecuador in the upper Amazon Basin indicates at least two avalanche events. Sangay Debris Avalanche-1 is the first deposit (250–100 Ka, as reported by Monzier et al., 1999), and Sangay Debris Avalanche-2 the younger deposit (~30 Ka, ¹⁴C dated). Both avalanches have a run-out distance of more than 60 km from Sangay's central crater. Statistical analysis of 541 counted hummocks shows that the largest hummocks are located in the middle run-out zone, between 40 and 50 km from the volcano. This middle zone possibly indicates that while in transport, the younger avalanche impacted laterally with a 500 m high ridge located SE of the volcano. The flow was redirected around this elevated, uplifted morphology. Petrological and geochemical data of clasts from the avalanche deposits have a similar affinity with late Holocene primary eruptive products from Sangay volcano. The vertical relief, mapped area, run-out distance, and the estimated deposit volumes categorize the two Sangay debris avalanche deposits as some of the furthest reaching volcanic slides related to continental volcanoes. Numerical simulations indicate that Sangay's potential future flank collapse could produce large debris avalanche deposits directed to the East, occupying the northern and southern drainage networks around the volcano. Several localities and towns would be affected, and the flow of major rivers would be blocked, and subsequent secondary lahars could have important discharges (1000 to 10,000 m³/s). We performed numerical simulations using the VolcFlow code, applying rheological parameters (plastic retarding stress of ~50 kPa) to simulate possible future debris avalanches of Sangay volcano.

桑盖火山是世界上最活跃的火山之一。它的喷发最早是在1628年由西班牙牧师记录的，自2010年以来，它大约每两年显示一次VEI 1-2级喷发活动。它的最新爆发阶段始于2019年5月7日，一直持续到现在。尽管大多数喷发性产品不会影响居民区，但桑盖的相关更新世时期雪崩矿藏却是巨大而深远的。现在，火山的E和SE围裙上的许多社区都布满了它们的表面。位于亚马逊河上游盆地厄瓜多尔东南部的桑盖碎片雪崩沉积研究表明，至少发生了两次雪崩事件。Sangay Debris Avalanche-1是第一个矿床（据Monzier等人，1999年报道为250-100 Ka），而Sangay Debris Avalanche-2是较年轻的矿床（〜30 Ka，C日期）。这两个雪崩的跳动距离桑盖的中央火山口均超过60公里。对541个被计数的山丘的统计分析表明，最大的山丘位于中间的跳动带，距火山40至50公里。该中间区域可能表明，在运输过程中，年轻的雪崩横向撞击了位于火山SE处500 m高的山脊。流量围绕这种升高的隆起形态重新定向。来自雪崩沉积的碎屑的岩石学和地球化学数据与桑盖火山晚期的全新世初生喷发产物具有相似的亲和力。垂直浮雕，地图区域，跳动距离，并且估计的沉积量将这两个Sangay碎片雪崩沉积物归类为与大陆火山相关的最远的火山滑坡。数值模拟表明，桑盖未来可能发生的侧翼坍塌可能会产生大量的碎屑雪崩沉积物，这些沉积物会流向东部，并占据火山周围的北部和南部排水网络。几个地方和城镇将受到影响，主要河流的流量将被阻塞，随后的次生拉哈尔可能会有重要的排放量（1000至10,000 m³ / s）。我们使用VolcFlow代码进行了数值模拟，应用流变参数（塑性阻滞应力约为50 kPa）来模拟Sangay火山未来可能发生的碎屑雪崩。