17:15 〜 18:45
[SCG54-P11] フンガ火山から採取された玄武岩とマグネシアン安山岩
キーワード：マグネシアン安山岩、西之島、薄い地殻、海底火山
On January 15, 2022, a large-scale eruption occurred at Hunga Volcano (Hunga Tonga-Hunga Haʻapai, HTHH), a submarine volcano in the Kingdom of Tonga. The eruption was the largest eruption in the last 140 years after the Krakatau 1883 eruption. Hunga Tonga-Hunga Ha’apai were the islands, which consist the summit of the large submarine Hunga volcano, which main body has not been studies yet. NIWA collected lavas from the Hunga Tonga-Hunga Ha’apai volcano during the emergency research cruise (TAN2206) in 2022, which includes sampling of rock specimens from the 2022 eruption. NIWA (National Institute of Water and Atmospheric Research Limited) and JAMSTEC collaborate in performing research and development on magmatic evolution process via analysis of the products of the large-scale eruption of Hunga Volcano, Kingdom of Tonga. The scientific objective of this collaborative research is to unveil the magmatic evolution process and the causes leading the eruptions of Hunga volcano via analysis of products of the large-scale eruption of Hunga Volcano, Kingdom of Tonga.
The Tongan Arc in the Kingdom of Tonga, the Kermadec Arc in New Zealand, and the Izu-Ogasawara Arc in Japan are composed of parts of the subduction zone of the Pacific Plate and have many similarities in their seismic activity and volcanic eruptions. Therefore, it is considered that the large-scale eruption of Hunga Volcano is not a unique event, that submarine volcanoes in the Izu-Ogasawara Arc and the Kermadec Arc could erupt in the near future, or that they may have erupted repeatedly in the past.
We found basalt and magnesian andesite lavas from the dredged samples, which were collected from the submarine flanks of Hunga volcano. These primitive andesites and basalts have never been observed from the Hunga Tonga-Hunga Haʻapai islands. These submarine rocks suggest the mantle-derived bimodal magmatism of basalt and andesite in Hunga volcano, which model has been presented in Nishinoshima volcano (Tamura et al., 2016; 2019; 2023).
The Tongan Arc in the Kingdom of Tonga, the Kermadec Arc in New Zealand, and the Izu-Ogasawara Arc in Japan are composed of parts of the subduction zone of the Pacific Plate and have many similarities in their seismic activity and volcanic eruptions. Therefore, it is considered that the large-scale eruption of Hunga Volcano is not a unique event, that submarine volcanoes in the Izu-Ogasawara Arc and the Kermadec Arc could erupt in the near future, or that they may have erupted repeatedly in the past.
We found basalt and magnesian andesite lavas from the dredged samples, which were collected from the submarine flanks of Hunga volcano. These primitive andesites and basalts have never been observed from the Hunga Tonga-Hunga Haʻapai islands. These submarine rocks suggest the mantle-derived bimodal magmatism of basalt and andesite in Hunga volcano, which model has been presented in Nishinoshima volcano (Tamura et al., 2016; 2019; 2023).