Lava channel roofing, overflows, breaches and switching: insights from the 2008-2009 eruption of Mt. Etna
Lava channel roofing, overflows, breaches and switching: insights from the 2008-2009 eruption of Mt. Etna
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熔岩通道顶部、溢出、缺口和转换：2008-2009 年埃特纳火山喷发的见解
DOI：
10.1007/s00445-011-0513-9
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发表时间：
2011
影响因子：
3.5
通讯作者：
James M
中科院分区：
文献类型：
--
作者：
James M
在长期的玄武岩喷发过程中，熔岩通道的溢流和通道水位的突破是广泛的“a 'a' a 'a' a 'a' a 'a' a 'a' a 'a' a 'a' a 'a' lava流场发展的重要过程。短暂的决口导致主河道附近地区被淹没。然而，如果一个缺口仍然开放，熔岩供应到原来的流动前沿显着减少，流场扩大有利于延长。因此，渠道决口和溢流的发展可以对整个流场的发展施加强有力的控制，但目前对决定其位置和频率的过程知之甚少。在2008-2009年火山爆发的最后一个月。在西西里的埃特纳火山，一个远程延时摄影机被用来监测一个小的短暂熔岩流的近端区域的事件。在约10小时的时间内，流动经历了表面高程和速度的变化，不同活力的重复溢出和通道顶部的建造（熔岩管形成的必要前奏）。图像序列的定量解释是由一个3D模型的场景构造使用结构从运动计算机视觉技术。由于表面活动减弱，在屋顶的过程中，溢流网站撤退了流向通风口，并最终，一个新的流量开始。我们的观察和测量表明，流动表面停滞和流动膨胀以约6 m h−1的有效速率传播向上流动，并且这些过程，而不是渗出率变化，最终导致最剧烈的溢流事件。我们讨论了类似的控制在levée突破和通道切换事件的证据，更大的流量埃特纳，如在2001年爆发。
During long-lived basaltic eruptions, overflows from lava channels and breaching of channel levées are important processes in the development of extensive 'a'ā lava flow-fields. Short-lived breaches result in inundation of areas adjacent to the main channel. However, if a breach remains open, lava supply to the original flow front is significantly reduced, and flow-field widening is favoured over lengthening. The development of channel breaches and overflows can therefore exert strong control over the overall flow-field development, but the processes that determine their location and frequency are currently poorly understood. During the final month of the 2008–2009 eruption of Mt. Etna, Sicily, a remote time-lapse camera was deployed to monitor events in a proximal region of a small ephemeral lava flow. For over a period of ~10 h, the flow underwent changes in surface elevation and velocity, repeated overflows of varying vigour and the construction of a channel roof (a required prelude to lava tube formation). Quantitative interpretation of the image sequence was facilitated by a 3D model of the scene constructed using structure-from-motion computer vision techniques. As surface activity waned during the roofing process, overflow sites retreated up the flow towards the vent, and eventually, a new flow was initiated. Our observations and measurements indicate that flow surface stagnation and flow inflation propagated up-flow at an effective rate of ~6 m h−1, and that these processes, rather than effusion rate variations, were ultimately responsible for the most vigorous overflow events. We discuss evidence for similar controls during levée breaching and channel switching events on much larger flows on Etna, such as during the 2001 eruption.