Tempo of post-glacial volcanism in southern Chile

要了解火山在未来可能会做什么，唯一的方法就是了解它们在过去的行为。该项目的重点是智利南部的大片地区-世界上火山最活跃的地区之一-以试图计算出该地区的火山在过去几千年中爆发了多少次。在智利的这一地区，火山爆发的历史记录只能追溯到19世纪初;即使是这些也不太可能是完整的。因此，了解更早喷发的唯一方法是寻找早期喷发的火山灰和浮石的储存地：在智利，这主要是在湖泊中。智利南部的许多火山在最后一次冰川期（大约20，000年前）被冰覆盖。许多高山冰川形成了长长的冰舌，延伸到这些火山前面（或西部）的平原上;当冰川消退时，它们留下了一系列大型的天然湖泊。在过去的18,000年里，这些湖泊一直在收集火山灰和其他沉积岩。比利时的科学家们一直在从这些湖泊中收集长泥芯，并开始利用它们从条纹状的泥层中读取过去气候和过去地震的记录。这个新项目的想法是从每个核心收集火山灰层。然后，我们将尝试将它们与在陆地上发现的相同火山灰层的其他例子相匹配（例如，火山附近;或道路切割;或泥炭沼泽和沼泽;甚至在一些剩余的冰川中），或在其他湖心中。一旦我们开始匹配这些层（使用多种因素的组合，例如它们的外观和成分），那么我们就能够为这些主要喷发的区域绘制一张时间图。与此同时，我们将测定小样本的碳（木炭），以更好地了解火山爆发发生的时间。当所有的信息放在一起，我们将有一个非常详细的记录气候，火山活动和地震在智利南部，从末次冰期结束到现在。最终的结果是，我们将能够确切地看到智利南部火山活动的速度在过去18,000年中是如何变化的-这就是我们所需要的，开始思考火山活动如何持续到未来。

The only way to understand what volcanoes might do in the future, is to understand how they have behaved in the past. This project focusses on a large area of southern Chile - one of the most volcanically active regions of the world - in order to try and work out how many times the volcanoes of this area have erupted over the past few thousand years. In this part of Chile, historical records of eruptions only go back to about the early 1800's; and even these are unlikely to be complete. So the only way to find out about older eruptions is look for places where ash and pumice from earlier eruptions is stored: and in Chile, this is mainly in lakes. Many of the volcanoes of southern Chile were covered in ice at the time of the last glaciation (about 20,000 years ago). Many of these mountain glaciers fed long tongues of ice which extended onto the plains in front of (or to the west of) these volcanoes; and as the glaciers retreated, they left behind a series of large, naturally dammed lakes. These lakes have been collecting volcanic ash and other sedimentary rocks for the past 18,000 years. Scientists from Belgium have been collecting long cores of mud from these lakes, and have started to use them to read the records of past climate, and past earthquakes, from the stripy layers of mud. The idea of this new project is to collect the layers of volcanic ash from each of these cores. Then we will try and match them to other examples of the same volcanic ash layer which are either found on land (e.g. near the volcanoes; or in road cuttings; or in peat bogs and marshes; or even in some of the remaining glaciers), or in other lake cores. Once we have started to match the layers (using a combination of factors, such as what they look like and what their composition is), then we will be able to put together a time-map for the region of these major eruptions. At the same time, we will date small samples of carbon (charcoal) to get a better idea of when the eruptions happened. When all of the information is put together, we will have a very detailed record of climate, volcanism and earthquakes in southern Chile, from the end of the last glaciation to the present day. The end result will be that we will be able to see exactly how rates of volcanic activity have changed over the past 18,000 years in southern Chile - and this is what we need, to start to think about how volcanic activity might continue into the future.