Understanding Controls on the Scale and Style of Explosive Volcanic Eruptions with Observational and Multi-Phase Computational Techniques

在上个世纪，活火山周围的人口密度迅速增加，事实上，今天大约有5亿人生活在世界上直接受到火山危害威胁的地区。火山碎屑流，或浮石和气体的高温高速雪崩，是爆炸性喷发造成破坏和生命损失的主要原因。1902年圣皮埃尔（马提尼克岛）27 000名居民死亡、1951年拉明顿（巴布亚新几内亚）毁灭性的火山爆发和上个世纪默拉皮（印度尼西亚）的火山爆发表明，火山爆发的影响可能极具破坏性。类似的影响在未来其他火山活跃地区也会出现。在监测、减灾和喷发后研究方面，过去20多年来最重要的两次喷发是1980年代圣海伦斯火山（MSH）的喷发和蒙特塞拉特苏弗里埃尔山火山（SHV）的持续喷发。每座火山在同一喷发期的不同时间，都表现出两种不同规模和风格的喷发——一种风格在几分钟后就中止了，产生了所谓的火山喷发，另一种风格继续而不是中止，从而产生了更大规模、持续的普林尼火山喷发。对这类爆炸的控制了解甚少，对减轻危害至关重要，因此是拟议研究的重点。我们之前的研究成功地将观测和现场数据与管道和爆炸模型进行了比较，验证了我们的计算方法。拟议的研究将以这项工作为基础，以两种方式确定对爆炸风格的显着控制。首先，由于我们之前的研究需要几个简化的假设，我们打算进一步发展导管流动模型，以增加岩浆系统的复杂性。其次，我们将分析不同规模和类型的爆炸：1996年在SHV持续的次普林尼期爆炸和1980年7月和8月在MSH的一系列短暂喷发。我们改进的模型结合实地研究的真实爆炸将导致更好地了解这种火山爆发的潜在影响。

EAR-0310329ClarkePopulation density around active volcanoes has increased rapidly over the last century, and in fact, roughly 500 million people today live in regions of the world directly threatened by volcanic hazards. Pyroclastic flows, or hot, high-speed avalanches of pumice and gas, are a major cause of destruction and loss of life in explosive eruptions. Their effects can be extremely destructive, as indicated by the deaths of 27,000 inhabitants of St. Pierre (Martinique) in 1902, the devastating eruption of Lamington (Papua New Guinea) in 1951, and the eruptions of Merapi (Indonesia) in the last century. Similar impacts can be anticipated in the future at other volcanically active locations. Two of the most important eruptions of the last 20+ years, with respect to monitoring, hazards mitigation and post-eruptive research, have been the eruptions of Mount St. Helens (MSH) during the 1980's and the ongoing eruption of the Soufriere Hills volcano, Montserrat (SHV). Each of these volcanoes, at different times during a single eruptive period, exhibited two different scales and styles of explosion - one style aborting after only a few minutes, generating what are termed Vulcanian explosions, and the other style continuing rather than aborting, thus producing larger-scale, sustained Plinian eruptions. The controls on such explosions are poorly understood, are imperative to hazard mitigation and are therefore the focus of the proposed research. Our previous studies successfully compared observational and field data from Vulcanian explosions at SHV with conduit and explosion models, validating our computational methods. The proposed research will build on this work in order to identify the salient controls on explosive style in two ways. First, because our previous studies required several simplifying assumptions, we intend to further develop the conduit flow model allowing for increased complexity of the magmatic system. Second, we will analyze explosions of different scales and styles: the 1996 sustained, sub-Plinian explosion at SHV and a series of short-lived eruptions at MSH, in July and August 1980. Our improved model combined with field-based studies of real explosions will lead to a better understanding of the potential impact of such volcanic eruptions.