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Evolution of the submarine–subaerial edifice of Bogoslof volcano, Alaska, during its 2016–2017 eruption based on analysis of satellite imagery
Bulletin of Volcanology ( IF 3.5 ) Pub Date : 2020-02-01 , DOI: 10.1007/s00445-020-1363-0
Christopher F. Waythomas , Kim Angeli , Rick L. Wessels

The 2016–2017 eruption of Bogoslof volcano involved at least 70 detected eruptive events between mid-December 2016 and August 30, 2017. Acquisition of high-resolution satellite imagery throughout the duration of the eruptive period allowed us to document and map the various morphologic changes that occurred on the subaerial part of Bogoslof Island. The emplacement of pyroclastic-flow and surge deposits caused the island to increase in area by about 1.5 km 2 . The dominant volcanic landforms of the eruption were a series of tuff rings emplaced around various submarine vents. Many of the tuff rings were mantled with surface dunes and impressive amounts of ballistic ejecta, likely derived from erupting magma bodies or previously emplaced submarine lava domes. Debris-flow deposits and surface channels extending over tuff ring surfaces apparent in multiple satellite images are evidence for explosive ejection of seawater. In most cases, erupting vents were initially submarine or began at subaerial lava domes and were largely flooded by seawater suggesting that water-magma ratios were likely high. Under such conditions where water is abundant, eruptive products typically reflect a high degree of water involvement and are dominated by the formation of wet tephra jets and flows and associated deposits typically consist of fine ash and lapilli, contain accretionary lapilli and ash aggregates, and usually form tuff cones and mounds. We observed none of these features in our analysis of satellite data or during our examination of eruptive deposits on Bogoslof Island in 2018. On the contrary, the dominant landform associated with the Bogoslof eruption was tuff rings. The development of tuff rings and surface dunes are commonly associated with the formation of pyroclastic base surges that are by comparison emplaced relatively dry. Dry base surge deposits can be generated from phreatomagmatic explosions involving superheated steam. It is possible that shallow submarine, magma–wet sediment interactions were a characteristic and possibly a dominant eruptive process of the 2016–2017 Bogoslof eruption.

中文翻译:

基于卫星图像分析的阿拉斯加博戈斯洛夫火山 2016-2017 年喷发期间海底-地下建筑的演变

2016 年至 2017 年博戈斯洛夫火山喷发涉及至少 70 次检测到的喷发事件,在 2016 年 12 月中旬至 2017 年 8 月 30 日期间。在整个喷发期间获取高分辨率卫星图像使我们能够记录和绘制各种形态变化发生在博戈斯洛夫岛的地面部分。火山碎屑流和涌浪沉积物的侵位导致该岛面积增加了约1.5 km 2 。喷发的主要火山地貌是一系列围绕海底喷口的凝灰岩环。许多凝灰岩环都覆盖着表面沙丘和大量弹道喷射物,可能来自喷发的岩浆体或先前放置的海底熔岩穹顶。在多张卫星图像中,碎屑流沉积物和延伸到凝灰岩环表面的地表通道是海水爆炸性喷射的证据。在大多数情况下,喷发的喷口最初是在海底或从地下熔岩穹顶开始,并且大部分被海水淹没,这表明水-岩浆比率可能很高。在这种水丰富的条件下,喷发产物通常反映了高度的水参与,并以湿火山喷流和流动的形成为主,相关沉积物通常由细灰和火山灰组成,包含增生的火山灰和火山灰聚集体,通常形成凝灰岩锥体和土丘。我们在分析卫星数据或检查 2018 年博戈斯洛夫岛上的喷发沉积物时没有观察到这些特征。 相反,与博戈斯洛夫火山喷发相关的主要地形是凝灰岩环。凝灰岩环和地表沙丘的形成通常与火山碎屑岩基底浪涌的形成有关,相比之下,火山碎屑基底浪涌相对干燥。干基浪涌沉积物可以由涉及过热蒸汽的潜水岩浆爆炸产生。浅层海底、岩浆-湿沉积物相互作用可能是 2016-2017 年 Bogoslof 喷发的一个特征,也可能是主要的喷发过程。
更新日期:2020-02-01
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