A singular precipitation event on the summit glacial slopes of Mexico’s highest volcanic peak, Citlatépetl (also known as Pico de Orizaba), associated with the passage of Hurricane Ernesto across the southern Mexico mainland in August 2012, resulted in a debris flow at altitudes above 4400 m asl, culminating in a hyperconcentrated flow downstream that had major impacts to a river valley’s channel morphology as well as to communities along a 25 km runout. The lahar originated at the terminal moraine and proglacial ramp of the Little Ice Age (LIA) extent of Citlaltépetl’s Jamapa glacier. Precipitation amounts were estimated based on nearby CONAGUA stations, but also on TRMM satellite images leading to an estimated 106 mm for a 3 day total, with 85 mm (80% of the total) falling on Aug 9th, the date when the lahar event occurred. The initial debris flow removed a minimum estimated 60,000 m3 of material from the proglacial ramp. A possible causative scenario is that the precipitation event overpressured the groundwater hydrology of an already unstable glacial-melt-saturated moraine. We demonstrate a methodology for the recreation of a pre-event landscape and the environmental conditions at the onset of the lahar, utilizing satellite products, in-situ geomorphological and geological evidence, and UAS technology.

中文翻译：

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墨西哥 Citlaltépetl (Pico de Orizaba) 火山 Jamapa 冰川排水系统沿线异常水文气象事件的上坡条件的重建。

墨西哥最高火山峰 Citlatépetl（也称为 Pico de Orizaba）的山顶冰川斜坡上发生的单一降水事件与 2012 年 8 月飓风埃内斯托穿越墨西哥南部大陆有关，导致海拔 4400 度以上的泥石流m asl，最终导致下游超浓流，对河谷的河道形态以及 25 公里径流沿线的社区产生重大影响。火山泥流起源于 Citlaltépetl 的 Jamapa 冰川小冰河时代 (LIA) 范围的终碛和前冰期斜坡。降水量是根据附近的 CONAGUA 站估计的，但也根据 TRMM 卫星图像估计，在 3 天的总降水量中估计为 106 毫米，其中 85 毫米（总量的 80%）落在了 8 月 9 日，即火山喷发事件发生的日期. 最初的泥石流从冰前斜坡移除了至少 60,000 立方米的物质。一个可能的原因是降水事件使已经不稳定的冰川融化饱和冰碛的地下水水文压力过大。我们展示了一种利用卫星产品、原位地貌和地质证据以及 UAS 技术重现事件前景观和火山喷发开始时的环境条件的方法。