Viscous flow of magmas from Unzen volcano, Japan - Implications for magma ascent and emplacement

缺乏对上升的高粘性导管岩浆流动特性的了解是预测火山爆发的一个主要缺陷。由于一种独特的高负荷高温变形装置的最新发展，现在第一次有可能确定流纹岩多相岩浆在火山爆发之前和爆发期间实际发生的应变速率下的有效非牛顿粘度。当Unzen的管道部分的核心最近被收购时，这个机会就出现了。总的来说，新技术和新样品的可用性提供了一个独特的机会，以推进对Unzen流变学的理解。新的数据将使完整的火山喷发模型在云岑的阐述。这些模型对于解释(a)浅层火山地震（如低频事件）及其作为近期火山喷发指标的潜在用途，(b) Unzen管道的自密封机制，以及(c) Unzen熔岩裂片的位移机制（可能指示非牛顿流动行为）具有重要意义。

The lack in understanding the flow behaviour of ascending highly viscous conduit magmas is a major drawback in forecasting explosive volcanic eruptions. Due to the very recent development of a unique high-load, high-temperature deformation apparatus it is now, for the first time, possible to determine the effective non-Newtonian viscosity of rhyolitic multi-phase magmas at strain rates actually occurring prior to and during volcanic eruptions. This opportunity comes when cores from a section of Unzen’s conduit were recently acquired. Taken together, the new technique and the new sample availability provide a unique opportunity to advance the rheological understanding of Unzen. The new data will enable the elaboration of complete volcanic eruption models at Unzen. Such models have important implications for the interpretation of (a) shallow volcanic earthquakes (e.g. low frequency events) and their potential use as indicators for near-future volcanic eruptions, (b) self-sealing mechanisms of the Unzen conduit, and (c) the poorly understood displacement mechanism of Unzen lava lobes, potentially indicative of non-Newtonian flow behaviour.