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Abstract Mass mortality of marine animals due to volcanic ash deposition is present in the fossil record but has rarely been documented in real time. Here, using remotely-operated vehicle video footage and analysis of ash collected at the seafloor, we describe the devastating effect of the record-breaking 2022 Hunga submarine volcanic eruption on endangered and vulnerable snail and mussel species that previously thrived at nearby deep-sea hydrothermal vents. In contrast to grazing, scavenging, filter-feeding, and predatory vent taxa, we observed mass mortality, likely due to smothering during burial by thick ash deposits, of the foundation species, which rely on symbiotic chemosynthetic bacteria for the bulk of their nutrition. This is important for our broad understanding of the natural disturbance of marine ecosystems by volcanic eruptions and for predicting the effects of anthropogenic disturbance, like deep-sea mining, on these unique seafloor habitats.
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How Did Westward Volcaniclastic Deposits Accumulate in the Deep Sea Following the January 2022 Eruption of Hunga Volcano?
Abstract Most volcanic eruptions on Earth take place below the ocean surface and remain largely unobserved. Reconstruction of past submerged eruptions has thus primarily been based on the study of seafloor deposits. Rarely before the 15 January 2022 eruption of Hunga volcano (Kingdom of Tonga) have we been able to categorically link deep‐sea deposits to a specific volcanic source. This eruption was the largest in the modern satellite era, producing a 58‐km‐tall plume, a 20‐m high tsunami, and a pressure wave that propagated around the world. The eruption induced the fastest submarine density currents ever measured, which destroyed submarine telecommunication cables and traveled at least 85 km to the west to the neighboring Lau Basin. Here we report findings from a series of remotely operated vehicle dives conducted 4 months after the eruption along the Eastern Lau Spreading Center‐Valu Fa Ridge. Hunga‐sourced volcaniclastic deposits 7–150 cm in thickness were found at nine sites, and collected. Study of the internal structure, grain size, componentry, glass chemistry, and microfossil assemblages of the cores show that these deposits are the distal portions of at least two ∼100‐km‐runout submarine density currents. We identify distinct physical characteristics of entrained microfossils that demonstrate the dynamics and pathways of the density currents. Microfossil evidence suggests that even the distal parts of the currents were erosive, remobilizing microfossil‐concentrated sediments across the Lau Basin. Remobilization by volcaniclastic submarine density currents may thus play a greater role in carbon transport into deep sea basins than previously thought.
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- PAR ID:
- 10656487
- Publisher / Repository:
- Geochemistry,Geophysics, Geosystems published byWiley Periodicals LLC on behalf ofAmerican Geophysical Union.
- Date Published:
- Journal Name:
- Geochemistry, Geophysics, Geosystems
- Volume:
- 26
- Issue:
- 4
- ISSN:
- 1525-2027
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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n this study, we investigate the source of an ash layer found in sediment core VM33-116 (Lat: -2.9, Long: 148.583), located in the Bismarck Sea. Originally, this research aimed to understand the impact of volcanic ash on biological productivity and climate. However, our findings suggest that the ash layer, dated to approximately 3000–4000 years ago, is most likely from a submarine volcanic eruption similar to the Hunga Tonga eruption of 2022. The ash layer (39–42 cm) contains an unusual spherule aggregate and black foraminifera. Experimental work has related the formation of spherule aggregates to the intense lightening in the high-altitude volcanic plume (58 km) produced by submarine eruptions like Hunga Tonga.) The black foraminifera are colored by black carbon on the inside of the foraminiferal test- a feature that might imply increase biological productivity. Elemental analysis using ITRAX and XRF revealed changes in Fe/Al and Ba/Al ratios, indicating volcanic ash deposition. However, no significant spikes in productivity-related elements (e.g., P, S, or Si) were observed, suggesting minimal impact on biological productivity. Corrected radiocarbon dating and geochemical analysis points to a submarine rhyolitic volcano located about 90 km from the core site as the likely source. Other nearby volcanoes, such as Tavui and Rabaul, are too distant to account for the ash. Our findings contribute to understanding the source of volcanic ash in the region and suggest that Hunga Tonga-type underwater eruptions can leave lasting geochemical markers, even across centuries. The presence of spherule aggregates and black foraminifera provides valuable insights into the effects of such eruptions on surrounding marine sediments Further research is needed to fully understand the relationship between submarine volcanic activity and its impact on biological productivity.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1029/2024GC011629
