The 6-8 Aug 2019 eruption of 'Volcano F' in the Tofua Arc, Tonga
The 6-8 Aug 2019 eruption of 'Volcano F' in the Tofua Arc, Tonga
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DOI：
10.1016/j.jvolgeores.2019.106695
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发表时间：
2020-01-15
影响因子：
2.9
通讯作者：
Hannington, Mark D.
中科院分区：
文献类型：
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作者：
Brandl, Philipp A.;Schmid, Florian;Hannington, Mark D.
2019年8月，一大批浮石出现在汤加领海。与许多其他情况一样，这块浮石筏是大型海底火山喷发的唯一表面表现。变色的水和利用卫星图像重建的浮石筏漂流路径指向位于瓦瓦乌岛Tofua Arc NW的F火山，这是最有可能的火山来源。在这里，我们展示了欧空局哨兵2号卫星拍摄的图像，该卫星捕捉到了2019年8月6日潜艇喷发的开始和8月8日喷发的减弱，随后对漂浮的浮石筏进行了观测，直到8月14日。这一开始时间与纽埃岛和拉罗通加地震台的T相记录一致，两台之间的S信号延迟时间与F火山或至少在F火山附近的起源一致。8月8日，海面出现了136.7公里(2)的大浮石筏。模拟的最小浮筏体积为8.2~41.0×106m(3)，相当于致密岩石的2.5~12.3×106m(3)，相当于海底环境中的火山爆炸性指数(VEI)2~3。在火山喷发之前，F火山附近记录了一系列地震。该系列地震于8月5日开始，震级为Mb 4.7级，随后在8月6日发生了至少6次浅源地震(Mb&Gt；3.9级)。2018年12月和2019年1月，我们用多波束声纳对F火山周围的海底进行了调查。结合我们的数据和先前存在的信息，我们提供了第一张全面的火山建筑物和它的地质背景的水深图。我们认为F火山代表了一个主要的弧形火山杂岩，它位于伸展环境中。火山停机坪的底部直径为50公里，中央有一个8.7x6公里的大火山口，底部类似于700米的水深。2004年，火山口后建筑圆锥体顶部的顶峰深度低于海平面35米。该火山与富努阿雷岛及晚期岛上相邻的弧形火山显示出不同的地球化学特征。该火山原始的火山形态和两次有记录的喷发(2001年和2019年)表明，一个高度活跃的火山系统值得进一步的科学关注。(C)2019爱思唯尔B.V.保留所有权利。
In August 2019 a large raft of pumice appeared in the territorial waters of Tonga. As in many other cases, this pumice raft was the only surface expression of a major submarine volcanic eruption. Discolored water and reconstruction of the drift path of the pumice raft using satellite imagery points towards 'Volcano F' in the Tofua Arc NW of the island of Vava'u as the most likely volcanic source. Here we present imagery from ESA's Sentinel-2 satellite that captured the start of the submarine eruption on 6 August 2019 and the waning of the eruption on 8 August, followed by observations of the drifting pumice raft until 14 August. This start time is consistent with T-phase records at the seismic stations on Niue Island and Rarotonga and the signal delay time of 733 s between the two stations is consistent with an origin at or at least near Volcano F. On 8 August, a >136.7 km(2) large raft of pumice appears at the sea surface. The modelled minimum raft volume is 8.2-41.0*10 6 m(3), which is equivalent to 2.5-12.3*10 6 m(3) dense rock The eruption thus corresponds to a volcanic explosivity index (VEI) 2-3 eruption in the submarine environment. Prior to the volcanic eruption, a series of earthquakes close to Volcano F was recorded. The series started on 5 August with a Mb 4.7 event, followed by at least six shallow earthquakes (Mb >3.9) on 6 August. In December 2018 and January 2019, we surveyed the seafloor around Volcano F with multibeam sonar. Combining our data with pre-existing information, we present the first comprehensive bathymetric map of the volcanic edifice and its geologic setting. We show that Volcano F represents a major arc volcanic complex that is situated in an extensional setting. The basal diameter of the volcanic apron is >50 km with a large central, 8.7 x 6 km caldera with a floor at similar to 700 m water depth. The top of the post-caldera constructional cone complex had a summit depth of 35 m below sea level in 2004. The volcano shows geochemical differences to the adjacent arc volcanoes on Fonualei and Late islands. The volcano's pristine volcanic morphology and two documented eruptions (2001 and 2019) indicate a highly active volcanic system that warrants further scientific attention. (C) 2019 Elsevier B.V. All rights reserved.