Extent and impact of distal ash fallout from the May 2008 eruption of Chaiten, Chile.

智利南部目前的大规模火山爆发为科学家提供了一个直接的机会，可以测量火山爆发期间和之后的细灰沉降物的影响。我们希望利用这个机会收集详细测量的厚度和粒度的灰已下降从Chaiten在阿根廷南部的一个非常大的面积的主要牧场。重要的是，这项工作要迅速进行-在火山灰被风吹到地面上之前，在火山灰被雨水沥滤之前。火山灰沉降物是火山爆发对人类及其生命支持系统（农业、交通、通信）的主要危害。即使只有一层薄薄的存款，也会对食草动物产生毁灭性的影响，因为它们要么拒绝吃灰尘覆盖的草（从而挨饿），要么消耗了与灰尘一起沿着的有毒盐（从而死于氟中毒）。目前，我们还没有足够复杂的模型来描述火山喷发后细灰的最终去向--主要是因为我们没有测试这些模型的测量方法。像这样的火山爆发，是一种主要的爆炸性喷发，存款在可到达的陆地区域（而不是海洋）沉积细灰，大约十年或更长时间才发生一次。这是自1991年皮纳图博（菲律宾）和哈德逊（智利）大爆发以来的第一次这样的机会。

The current major explosive volcanic eruption in southern Chile presents an immediate opportunity for scientists to measure the impact of fine ash fallout during and after an eruption. We wish to use this opportunity to collect detailed measurements of the thickness and grainsize of ash which has fallen from Chaiten across a very large area of prime grazing land in southern Argentina. It is important that this work is carried out quickly - before the ash has been moved around on the ground by winds, and before the ash has been leached by rain water. Ash fallout is the major hazard from volcanic eruptions to humans, and their life-support systems (agriculture, transport, communications). Even only a thin deposit of ash can have a devastating effect on grazing animals, since they either refuse to eat ash-dusted grasses (and starve); or they consume the toxic salts deposited along with the ash (and die of fluorosis). At the moment, we so not have sufficiently sophisticated models of where fine ash ends up after eruptions - mainly because we do not have the measurements to test these models. Eruptions such as this, which are major explosive eruptions and which deposit fine ash across accessible land areas (rather than the sea), only happen about once in a decade or more. This is the first such opportunity since the major explosive eruptions of Pinatubo (Philippines) and Hudson (Chile) in 1991.