Enormous and far-reaching debris avalanche deposits from Sangay volcano (Ecuador): Multidisciplinary study and modeling the 30 ka sector collapse

Valverde Viviana; Mothes Patricia A.; Beate Bernardo; Bernard Julien

摘要

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 (similar to 30 Ka, C-14 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 m(3)/s). We performed numerical simulations using the VolcFlow code, applying rheological parameters (plastic retarding stress of similar to 50 kPa) to simulate possible future debris avalanches of Sangay volcano. (C) 2021 Elsevier B.V. All rights reserved.

机译：桑太是世界上最活跃的火山之一。它的爆发是由西班牙牧师于1628年录制的，自2010年以来，它显示了每两年大约一两年的爆发活动。其最近的爆发相开始于2019年5月7日，并持续到目前。虽然大多数喷发产品不会影响居住地区，但桑耶的相关百良生茂雪茄矿床巨大而深远。他们的表面现在被火山的e和se围裙上的许多社区填充。 Sangay的碎片 - 雪崩沉积物在上亚马逊盆地的SE厄瓜多尔的研究表明至少有两种雪崩事件。 Sangay Debris Avalanche-1是第一款押金（250-100 KA，如Monzier等，1999），桑太碎片雪崩-2年轻的沉积物（类似于30 kA，C-14日期）。雪崩均距离桑耶的中央火山山有超过60公里的跑道。统计分析541次计数的水管显示，最大的小木木位于中间跑区，距离火山40到50公里。这个中间区可能表明，在运输时，年轻的雪崩横向影响火山的500米高的脊。该流程被重定向到这种升高的升高的形态。来自雪崩沉积物的岩浆的岩浆和地球化学数据具有与Sangay火山的晚全新型原发性喷发产品类似的亲和力。垂直浮雕，映射区域，跑出距离和估计的存款量将两个桑太碎片雪崩沉积物分类为与大陆火山有关的火山幻灯片中的一些。数值模拟表明，桑耶的潜在未来的侧翼塌陷可以产生针对东部的大型碎片雪崩沉积物，占据火山周围的北部和南方排水网络。几个地方和城镇会受到影响，主要河流的流动将被阻止，后续的次级拉哈尔尔可能具有重要的排放（1000至10,000米（3）/ s）。我们使用Volcflow代码进行了数值模拟，应用流变参数（类似于50 kPa的塑料延迟应力）来模拟桑太火山可能的未来碎片雪崩。（c）2021 Elsevier B.v.保留所有权利。

Enormous and far-reaching debris avalanche deposits from Sangay volcano (Ecuador): Multidisciplinary study and modeling the 30 ka sector collapse

摘要

著录项

相关主题

期刊订阅