Complex dynamics of small-moderate volcanic events: the example of the 2011 rhyolitic Cordón Caulle eruption, Chile
Complex dynamics of small-moderate volcanic events: the example of the 2011 rhyolitic Cordón Caulle eruption, Chile
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中小火山事件的复杂动态：以 2011 年智利 Cordón Caulle 流纹岩喷发为例
DOI：
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发表时间：
2015
影响因子：
3.5
通讯作者：
L. Francalanci
中科院分区：
文献类型：
--
作者：
M. Pistolesi;R. Cioni;C. Bonadonna;M. Elissondo;V. Baumann;A. Bertagnini;Laura Chiari;Rafael Gonzales;M. Rosi;L. Francalanci
经过几十年的沉寂，Puyehue-Cordón Caulle火山（智利）在2011年6月爆发，此前一个月的地震活动持续增加。此次火山喷发使大量流纹岩灰散在大面积范围内，具有复杂的动力学特征。在喷发的初始高潮阶段（6月4日至5日24-30小时），11 - 14公里高的羽状物将大部分喷发的火山灰向东扩散到阿根廷，最远到达大西洋。在第一次喷发阶段之后，由于风向和喷发方式的快速变化，导致了较低强度的活动，导致了复杂地层层序的发育。由此产生的麻风矿床由13个主要层组成，分为四个单元。根据各层的扩散方向、沉积学特征以及幼期组分的主要特征（结构、密度、岩石学、化学）对各层进行了表征。喷发序列的最低部分（第1单元），对应于6月4日至5日喷发的tephra，由交替的小丘层组成，估计总体积约为0.75 km3；这些层记录了最高强度的阶段，在此期间，一个弯曲的羽状物向东南方向分散了热气流，向上风向的沉积可以忽略不计。6月5日至6日期间（第2单元）排放的产品表明风向突然向北转变，导致北部地区沉积粗灰沉积物（体积约0.21 km3），随后恢复东风。第三阶段（第三单元）于6月7日开始，结果在东部地区发现了热风沉积物和在喷口地区周围发现了弹道炸弹。最后一个阶段（第四阶段）开始于6月15日之后，其特点是在低水平活动期间，从带火山灰的羽状物中喷出细粒白色麻风，并挤出粘性熔岩流。通过与卫星图像比较主要天热层的分布，对第一次喷发阶段的时间和持续时间进行了限制，表明大部分天热层是在事件的前72小时内发射的。所分析的幼崽物质紧密地聚集在流纹岩场内，通过喷发序列的化学变化可以忽略不计。构造观测表明，喷发强度的变化（以及由此导致的岩浆在管道内上升速度的变化）以及上升过程中富气岩浆和贫气岩浆之间复杂的相互作用导致了囊状碎屑具有不同程度的剪切局部化，并且可能导致了幼体物质的大非均质性。
After decades of repose, Puyehue-Cordón Caulle Volcano (Chile) erupted in June 2011 following a month of continuously increasing seismic activity. The eruption dispersed a large volume of rhyolitic tephra over a wide area and was characterized by complex dynamics. During the initial climactic phase of the eruption (24–30 h on 4–5 June), 11–14-km-high plumes dispersed most of the erupted tephra eastward towards Argentina, reaching as far as the Atlantic Ocean. This first eruptive phase was followed by activity of lower intensity, leading to the development of a complex stratigraphic sequence, mainly due to rapid shifts in wind direction and eruptive style. The resulting tephra deposits consist of 13 main layers grouped into four units. Each layer was characterized based on its dispersal direction, sedimentological features, and on the main characteristics of the juvenile fraction (texture, density, petrography, chemistry). The lowest part of the eruptive sequence (Unit I), corresponding to the tephra emitted between 4 and 5 June, is composed of alternating lapilli layers with a total estimated volume of ca. 0.75 km3; these layers record the highest intensity phase, during which a bent-over plume dispersed tephra towards the southeast-east, with negligible up-wind sedimentation. Products emitted during 5–6 June (Unit II) signaled an abrupt shift in wind direction towards the north, leading to the deposition of a coarse ash deposit in the northern sector (ca. 0.21 km3 in volume), followed by a resumption of easterly directed winds. A third phase (Unit III) began on 7 June and resulted in tephra deposits in the eastern sector and ballistic bombs around the vent area. A final phase (Unit IV) started after 15 June and was characterized by the emission of fine-grained white tephra from ash-charged plumes during low-level activity and the extrusion of a viscous lava flow. Timing and duration of the first eruptive phases were constrained based on comparison of the dispersal of the main tephra layers with satellite images, showing that most of the tephra was emitted during the first 72 h of the event. The analyzed juvenile material tightly clusters within the rhyolitic field, with negligible chemical variations through the eruptive sequence. Textural observations reveal that changes in eruption intensity (and consequently in magma ascent velocity within the conduit) and complex interactions between gas-rich and gas-depleted magma portions during ascent resulted in vesicular clasts with variable degrees of shear localization, and possibly in the large heterogeneity of the juvenile material.
2008 年 5 月智利 Chaitén 喷发的火山灰地层和喷发量
影响因子：
3.5
作者：
Alfano F
通讯作者：
Alfano F