Recent Eruptions Between 2012 and 2018 Discovered at West Mata Submarine Volcano (NE Lau Basin, SW Pacific) and Characterized by New Ship, AUV, and ROV Data
Recent Eruptions Between 2012 and 2018 Discovered at West Mata Submarine Volcano (NE Lau Basin, SW Pacific) and Characterized by New Ship, AUV, and ROV Data
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DOI：
10.3389/fmars.2019.00495
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发表时间：
2019-08-20
影响因子：
3.7
通讯作者：
Embley, Robert W.
中科院分区：
文献类型：
--
作者：
Chadwick, William W., Jr.;Rubin, Kenneth H.;Embley, Robert W.
西马塔是一座海底火山，位于斐济和萨摩亚之间的西南太平洋东北劳盆地。西马塔火山在2008年9月和2009年5月的高峰期被发现活跃喷发。水柱化学和水听器数据表明，它可能一直活跃到2011年初。随后对西马塔的多次测深调查表明，从那时起，它改变了远离山顶的频繁但间歇性喷发的风格。我们提供了来自船基测深调查的新数据，来自自主水下航行器的高分辨率测深，以及远程操作潜水器潜水的观测结果，这些数据记录了2012年至2018年期间的四次额外喷发。其中三次喷发发生在2012年9月至2016年3月之间;一次在上ENE裂谷的山顶附近，第二次在远离任何裂谷带的东北侧，第三次在火山的东北基地。后者将岩床侵入到一个有厚厚沉积物的盆地中，将沉积物抬升，然后将熔岩挤出到周围的海底。最近的四次喷发发生在2016年3月至2017年11月之间，沿着中ENE裂谷带，并产生了具有瓦片状形态和火山灰的枕状熔岩流以及覆盖东南斜坡的碎屑碎片。潜水观测表明，西马塔最近较浅的喷发包括大量的火山碎屑成分，其基础是喷发口附近厚（> 1米）的火山灰沉积物。最深的喷发点缺乏这些近喷口火山灰沉积物，这表明火山碎屑活动是最小的低于类似2500 mbsl。多波束声纳重新测量限制了新喷发的时间、厚度、面积、形态和体积。自1996年以来的累积喷发量表明，西马塔的喷发量是可以预测的，平均喷发率为7.8 x 10（6）m（3）/年。相对较低的岩浆供应率和高频率的喷发（每1-2年）表明西马塔的岩浆库相对较小。由于活动频繁，西马塔仍然是研究海底火山爆发的理想天然实验室。
West Mata is a submarine volcano located in the SW Pacific Ocean between Fiji and Samoa in the NE Lau Basin. West Mata was discovered to be actively erupting at its summit in September 2008 and May 2009. Water-column chemistry and hydrophone data suggest it was probably continuously active until early 2011. Subsequent repeated bathymetric surveys of West Mata have shown that it changed to a style of frequent but intermittent eruptions away from the summit since then. We present new data from ship-based bathymetric surveys, high-resolution bathymetry from an autonomous underwater vehicle, and observations from remotely operated vehicle dives that document four additional eruptions between 2012 and 2018. Three of those eruptions occurred between September 2012 and March 2016; one near the summit on the upper ENE rift, a second on the NE flank away from any rift zone, and a third at the NE base of the volcano. The latter intruded a sill into a basin with thick sediments, uplifted them, and then extruded lava onto the seafloor around them. The most recent of the four eruptions occurred between March 2016 and November 2017 along the middle ENE rift zone and produced pillow lava flows with a shingled morphology and tephra as well as clastic debris that mantled the SE slope. ROV dive observations show that the shallower recent eruptions at West Mata include a substantial pyroclastic component, based on thick (> 1 m) tephra deposits near eruptive vents. The deepest eruption sites lack these near-vent tephra deposits, suggesting that pyroclastic activity is minimal below similar to 2500 mbsl. The multibeam sonar re-surveys constrain the timing, thickness, area, morphology, and volume of the new eruptions. The cumulative erupted volume since 1996 suggests that eruptions at West Mata are volume-predictable with an average eruption rate of 7.8 x 10(6) m(3)/yr. This relatively low magma supply rate and the high frequency of eruptions (every 1-2 years) suggests that the magma reservoir at West Mata is relatively small. With its frequent activity, West Mata continues to be an ideal natural laboratory for the study of submarine volcanic eruptions.