When Does Magma Break
When Does Magma Break
复制标题
岩浆什么时候破裂
DOI：
10.1007/11157_2017_23
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发表时间：
2017
影响因子：
2.9
通讯作者：
B. Scheu
中科院分区：
文献类型：
--
作者：
F. Wadsworth;T. Witcher;J. Vasseur;Donald Bruce Dingwell;B. Scheu
到达地球表面的地球物理信号源自深处的源机制，但不一定是直接可观察的。因此，适定实验可以提供对源力学的深入了解，重要的是，可以提供对动荡信号源的各个方面进行建模所需的参数。在本章中，我们将详细介绍一个这样的例子，说明实验室工作如何提高我们对不安信号的理解。我们专注于单相和多相岩浆的故障，表明液体粘度，因此，温度和挥发物含量的一个给定的组合物的岩浆，是在确定岩浆是否会上升粘性或它是否可以在上升过程中断裂的限制参数。这个临界阈值的特征在于一个德博拉数，放松的时间尺度的局部流动的时间尺度的比率。我们表明，对于单相岩浆液体和强烈的泡状岩浆，局部Deborah数为10^{ - 2}是极限，在该极限以上，可以预期包括断裂扩展的混合粘弹性行为，Deborah数为1是极限，在该极限以上，岩浆主要是弹性的，并以脆性的方式响应于施加的应力。这些阈值可以理解为粘弹性液体的德拜弛豫过程的开始和峰值。麦克斯韦模型的明显有效性，使我们能够预测的最大应力，可以支持的火山液体变形在高德博拉数范围内。我们使用这些约束条件，以提供一个地图上的时间尺度，我们轮廓占主导地位的系统响应，从粘性到纯脆性，有效的所有岩浆液体。最后，我们探讨必要的缩放扩展这些概念的见解，晶体和泡沫轴承岩浆在特定条件下有效。岩浆变形和松弛的竞争时间尺度与源于岩浆变形的不稳定源机制有关，例如用于预测喷发时间的长周期地震信号。
Geophysical signals arriving at the Earth’s surface originate from a source mechanism at depth but are not necessarily directly observable. Therefore, well-posed experiments can provide insights into source mechanics and, importantly, the parameters required to model aspects of the sources of unrest signals. In this Chapter we detail one such example of how experimental laboratory work has improved our understanding of unrest signals. We focus on the failure of single- and multi-phase magmas, demonstrating that the liquid viscosity, and therefore the temperature and volatile content of a magma of a given composition, is the limiting parameter in determining whether a magma will ascend viscously or whether it can fracture during ascent. This critical threshold is characterized by a Deborah number, the ratio of the timescale of relaxation to the timescale of local flow. We show that for single-phase magmatic liquids and for vigorously vesiculating magmas, a local Deborah number of \( 10^{ - 2} \) is the limit above which mixed viscoelastic behaviour including fracture propagation can be expected, and a Deborah number of \( 1 \) is the limit above which magma is dominantly elastic and responds in a brittle manner to applied stresses. These thresholds can be understood in terms of the onset and peak of the Debye relaxation process for viscoelastic liquids. The apparent validity of a Maxwell model permits us to predict the maximum stress that can be supported by a volcanic liquid deforming in the high Deborah number range. We use these constraints to provide a map of timescales on which we contour dominant system responses from viscous to purely brittle; valid for all magmatic liquids. Finally, we explore the scaling necessary to extend these conceptual insights to crystal- and bubble-bearing magmas valid under specific conditions. The competing timescales of deformation and relaxation in magma are relevant to unrest source mechanisms that originate from magma deformation, such as long-period seismic signals that are used to predict eruption timing.
影响因子：
64.8
作者：
Lavallee, Y.;Meredith, P. G.;Kruhl, J. H.
通讯作者：
Kruhl, J. H.
影响因子：
5.8
作者：
Cordonnier, B.;Caricchi, L.;Burlini, L.
通讯作者：
Burlini, L.
DOI：
10.1098/rspa.2009.0445
发表时间：
2010-04-08
影响因子：
3.5
作者：
Mueller, S.;Llewellin, E. W.;Mader, H. M.
通讯作者：
Mader, H. M.