PDF(Pubmed)
Abstract：
On 15 January 2022, Hunga volcano erupted, creating an extensive and high-reaching umbrella cloud over the open ocean, hindering traditional isopach mapping and fallout volume estimation. In MODIS satellite imagery, ocean surface water was discolored around Hunga following the eruption, which we attribute to ash fallout from the umbrella cloud. By relating intensity of ocean discoloration to fall deposit thicknesses in the Kingdom of Tonga, we develop a methodology for estimating airfall volume over the open ocean. Ash thickness measurements from 41 locations are used to fit a linear relationship between ash thickness and ocean reflectance. This produces a minimum airfall volume estimate of 1.8-0.4+0.3 km3. The whole eruption produced > 6.3 km3 of uncompacted pyroclastic material on the seafloor and a caldera volume change of 6 km3 DRE. Our fall estimates are consistent with the interpretation that most of the seafloor deposits were emplaced by gravity currents rather than fall deposits. Our proposed method does not account for the largest grain sizes, so is thus a minimum estimate. However, this new ocean-discoloration method provides an airfall volume estimate consistent with other independent measures of the plume and is thus effective for rapidly estimating fallout volumes in future volcanic eruptions over oceans.
UNASSIGNED: The online version contains supplementary material available at 10.1007/s00445-024-01744-6.
UNASSIGNED: The online version contains supplementary material available at 10.1007/s00445-024-01744-6.
摘要：
2022年1月15日，洪加火山爆发，在开阔的海洋上形成广泛而深远的伞状云，阻碍传统的等比奇映射和沉降量估计。在MODIS卫星图像中,火山喷发后，洪加周围的海洋地表水变色，我们将其归因于伞云中的灰烬。通过将汤加王国的海洋变色强度与下降沉积物厚度相关联，我们开发了一种估计公海上的空降量的方法。来自41个位置的灰分厚度测量用于拟合灰分厚度与海洋反射率之间的线性关系。这产生了1.8-0.4+0.3km3的最小落空体积估计值。整个喷发在海底产生了>6.3km3的未压实火山碎屑材料，火山口体积变化为6km3DRE。我们的秋季估计与大多数海底沉积物是由重力流而不是秋季沉积物沉积的解释一致。我们提出的方法没有考虑最大的晶粒尺寸，因此是最小估计。然而,这种新的海洋变色方法提供了与羽流的其他独立措施一致的落空量估计，因此可有效地快速估计未来海洋火山喷发中的落落量。
■在线版本包含补充材料，可在10.1007/s00445-024-01744-6获得。
■在线版本包含补充材料，可在10.1007/s00445-024-01744-6获得。
