The micromechanics of strain localization in partially - molten silicic magma chambers: keys for understanding the origin, and dynamics of "supervolcanic" eruptions

部分熔融硅质岩浆房应变局部化的微观力学：理解“超级火山”喷发的起源和动力学的关键

• 批准号: 262856-2008
• 负责人: Jellinek, Andrew
• 金额: $ 2.19万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=480249
• 关键词: micromechanics; strain; localization; partially; molten; micromechanics; strain; localization; partially; molten

Catastrophic caldera-forming eruptions during which thousands of cubic kilometers of very viscous and crystal-rich magma is erupted explosively over a time scale of days to weeks are among the most awesome natural phenomena on Earth. Such events have occurred intermittently throughout Earth's history in places such as the Yellowstone caldera, USA and in the Taupo volcanic zone, New Zealand. Magmas feeding these so-called "supervolcanic eruptions" are thought to be driven from high-level chambers, in part, by a time-dependent piston-like foundering of a dense chamber roof into an underlying laterally-extensive molten or partially-molten magma chamber of lower density. Whereas the volumes of such eruptions are perhaps not surprising, as they are expected to proceed until most or all buoyant magma is expelled, an explanation for the extreme rate of eruption remains one of the most compelling problems in volcanology. In detail, the physical problem governing the rate of eruption is analogous to the rapid compaction and disaggregation of a strong, deformable porous medium constructed of a solid crystalline matrix and a viscous interstitial pore fluid. The inherent mechanical difficulty with disrupting and expelling such a material places restrictive demands on the underlying magma chamber processes. This proposal uses a novel combination of field observations, laboratory fluid dynamics experiments, theoretical work and numerical simulations to identify and understand the magma chamber dynamics that enable such a large volume of crystal-rich material to be erupted so quickly.

灾难性的火山口形成喷发，在此期间，在几天到几周的时间范围内，数千立方公里的非常粘性和富含晶体的岩浆爆发爆发是地球上最令人敬畏的自然现象之一。在整个地球历史上，在美国黄石火山口和新西兰的陶波火山区等地发生了这种事件。 岩浆喂养这些所谓的“超级爆发”被认为是由高级腔室驱动的，部分是由于时间依赖的活塞式腔室屋顶的成立，进入了一个下层横向延伸的熔融或部分较低密度的部分。尽管这种喷发的数量也许并不奇怪，因为预计将在大多数或所有浮力岩浆被驱逐之前进行，而对极端喷发率的解释仍然是火山学上最引人注目的问题之一。 详细说明，控制喷发速率的物理问题类似于由固体晶体基质和粘性的间质孔隙流体构成的强，可变形的多孔培养基的快速压实和分解。 固有的机械难度在破坏和驱逐这种物质的位置对基础岩浆腔室过程的限制性要求。该提案使用了现场观测，实验室流体动力学，理论工作和数值模拟的新型组合来识别和理解岩浆室动力学，从而使如此大量的富含晶体的材料如此迅速地爆发。