Necking and fracking may explain stationary seismicity and full degassing in volcanic silicic spine extrusion
Necking and fracking may explain stationary seismicity and full degassing in volcanic silicic spine extrusion
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颈缩和水力压裂可以解释火山硅质脊柱挤压过程中的静止地震活动和完全脱气
DOI：
10.1016/j.epsl.2018.09.023
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发表时间：
2018
影响因子：
5.3
通讯作者：
S. Wei
中科院分区：
文献类型：
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作者：
Liqing Jiao;P. Tapponnier;F. Costa;F. Donze;L. Scholtès;B. Taisne;S. Wei
火山喷发期间的火山地震活动通常涉及在火山口下方固定深度的类似源的反复激发。火山脊挤压的力学可以与高温工业金属加工的力学相比较。因此，我们使用滑移线场理论来评估上升岩浆中的应力、应变和断层，虽然岩浆很热，但表现得像固体。2004年9月至2005年8月圣海伦火山爆发期间的地震断层面的解决方案通常是一致的收缩上升的岩浆通过管道“瓶颈”。在215个断层面解中，逆冲断层面和垂直断层面占优势，正断层或走滑断层较少。因此，主要是颈部的收缩和沿着管壁的垂直剪切。动态离散元模拟再现重复的成核和逆冲断层在这样一个颈部的增长。通过颈部核心的压降（二次张力）促进裂缝张开，从而促进气体提取。这种天然的“水力压裂”可以促进岩浆的完全脱气，从而有助于形成典型的低爆炸性的棘状突起。
Volcanic seismicity during silicic spine eruptions often involves recurrent excitation of similar sources at stationary depth just beneath the crater. The mechanics of volcanic spine extrusion may be compared to those of high-temperature, industrial metal working. We thus use slip-line field theory to assess stress, strain and faulting in ascending magma, which, although hot, behaves as a solid. Earthquake fault-plane solutions during the 09/2004-08/2005 eruptions of Mount St. Helens are generally consistent with shrinking of magma rising across a conduit "bottle-neck". Among 215 fault plane solutions, thrust and vertical fault planes prevail, with fewer normal or strike-slip faults. Constriction across the neck and vertical shear along the conduit walls thus predominate. Dynamic Discrete Element Modeling reproduces repetitive nucleation and growth of thrust faults within such a neck. The pressure drop across the neck's core (secondary tension) boosts crack opening and hence gas extraction. Such natural "fracking" could promote full magma degassing, contributing to the typically low explosivity of silicic spine extrusion.
DOI：
--
发表时间：
1975-10
期刊：
--
影响因子：
--
作者：
H. Kanamori;D. L. Anderson
通讯作者：
H. Kanamori;D. L. Anderson