Geology and Recent Volcanology of Nevado del Ruiz Volcano, Colombia

为了研究哥伦比亚的内瓦多德尔鲁伊斯活火山，计划了一个包括地质学、地球物理学和地球化学在内的为期三年的综合计划。自1985年11月喷发以来，PI一直在鲁伊斯从事一系列不同的初步项目，这些项目表明之前对火山的看法可能是错误的。为了加深我们对安第斯火山作用的理解，并对安第斯火山作用的一般概念模型作出贡献，我们制定了一个由四项任务组成的计划：1)对火山杂岩进行详细的地质研究，包括分析火山活动的时代、演化、喷发动力学、岩石学和火山灾害。2)对该地区广泛分布的九个已知的火山灰层中记录的火山近期行为的研究。喷发量、动力学和演化将是主要焦点。3)详细的重力研究，以评估和模拟鲁伊斯的地下结构。关于鲁伊斯的形态和行为的不寻常方面的大多数问题，如果真的存在一个无法识别的火山口，就可以得到解决。4)继续分析地热系统及其对岩浆中涌的响应。将努力对该系统进行更完整的采样，分析蚀变产物，确定其年龄及其与地质演化的关系。将进行更多的同位素研究，以了解深层储集层的性质以及主要和次要成分的来源。这项研究的目标是制作一个主要的北安第斯火山中心的综合模型，然后将其应用于其他环太平洋火山并与之进行比较。

An integrated three-year program including geology, geophysics and geochemistry is planned for the purpose of studying the active volcano Nevado del Ruiz, Colombia. Since the November, 1985 eruption, the PI has been engaged in a diverse set of preliminary projects at Ruiz which suggest that previously held beliefs about the volcano may be in error. In order to improve our understanding and to contribute to the general conceptual model of Andean volcanism a four-task program has been developed: 1) A detailed geological study of the volcanic complex including analyusis of the age of volcanism, its evolution, eruption dynamics, petrology, and volcanic hazards. 2) A study of recent behavior of the volcano as recorded in the nine known tephra layers distributed widely over the region. Eruption volumes, dynamics and evolution will be a primary focus. 3) A detailed gravity study to evaluate and model the subsurface structure of Ruiz. Most of the questions about the unusual aspects of the form and behavior of Ruiz could be resolved if an unrecognized caldera were actually present. 4) A continued analysis of the geothgermal system and its response to the mesurgence of magma. An effort will be made to more completely sample the system, analyze the alteration products, and determine their age and relationship to the geological evolution. Additional isotopic studies will be undertaken to understand the nature of the deep reservoir and the origins of the main and minor constituents. The goal of the research is to produce an integrated model of the major northern Andean volcanic center which could then be applied to and compared with those developed at other circumPacific volcanoes.