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[SIT19-01] The stealth hotspot volcanoes
Keywords:Catastrophic eruptions, Slab window, Seismic tomography, Subslab mantle structure
Catastrophic volcanic eruptions with the destructive power to end civilizations typically occur at island arc volcanoes in subduction zones. The island arc volcanoes originate from corner flow in the mantle wedge (Figure (A)) and are distinct from hotspot volcanoes with origins in the deep mantle. However, recent studies have suggested that hot mantle upwelling beneath the subducted plate (=slab) might play a role in generating megathrust earthquakes (e.g., Fan & Zhao, 2021) and in triggering catastrophic eruptions (e.g., Toyokuni et al., 2022; Hu et al., 2023; Toyokuni & Zhao, 2024).
This study comprehensively examines the relationship between the catastrophic eruptions and the subsurface structures revealed by high-resolution seismic tomography of five major subduction zones, i.e., Southeast Asia, Eastern Mediterranean, Japan, Australia-New Zealand, and South America. Using the latest tomographic methods (Zhao et al., 2017), we have determined detailed P-wave velocity structural models from the surface to the lower mantle beneath the target regions. The results indicate that many catastrophic eruptions occurred in areas where a slab window exists and where low-velocity anomalies in both the mantle wedge and the sub-slab are well developed. In other words, catastrophic eruptions may occur when corner flow in the mantle wedge interacts with sub-slab hot mantle upwelling through a slab window (Figure (B)). Volcanoes that produce such catastrophic eruptions can be considered as hotspot volcanoes nestled within island arc volcanic chain, and thus can be termed "stealth" hotspot volcanoes (Figure (C)). This model provides a unified explanation for many catastrophic eruptions and might help constrain the risks of such eruptions through the study of subsurface structures, which is important for disaster prevention.
References:
Fan, J. & Zhao, D. (2021) Nature Geosci., 14, 349–353.
Hu, H., Zhao, D., Lin, J. & Pilia, S. (2023) JGR Solid Earth, 128, e2022JB025976.
Toyokuni, G. & Zhao, D. (2024) G-Cubed, 25, e2024GC011739.
Toyokuni, G., Zhao, D. & Kurata, K. (2022) JGR Solid Earth, 127, e2022JB024298.
Zhao, D., Fujisawa, M. & Toyokuni, G. (2017) Sci. Rep., 7, 44487.
This study comprehensively examines the relationship between the catastrophic eruptions and the subsurface structures revealed by high-resolution seismic tomography of five major subduction zones, i.e., Southeast Asia, Eastern Mediterranean, Japan, Australia-New Zealand, and South America. Using the latest tomographic methods (Zhao et al., 2017), we have determined detailed P-wave velocity structural models from the surface to the lower mantle beneath the target regions. The results indicate that many catastrophic eruptions occurred in areas where a slab window exists and where low-velocity anomalies in both the mantle wedge and the sub-slab are well developed. In other words, catastrophic eruptions may occur when corner flow in the mantle wedge interacts with sub-slab hot mantle upwelling through a slab window (Figure (B)). Volcanoes that produce such catastrophic eruptions can be considered as hotspot volcanoes nestled within island arc volcanic chain, and thus can be termed "stealth" hotspot volcanoes (Figure (C)). This model provides a unified explanation for many catastrophic eruptions and might help constrain the risks of such eruptions through the study of subsurface structures, which is important for disaster prevention.
References:
Fan, J. & Zhao, D. (2021) Nature Geosci., 14, 349–353.
Hu, H., Zhao, D., Lin, J. & Pilia, S. (2023) JGR Solid Earth, 128, e2022JB025976.
Toyokuni, G. & Zhao, D. (2024) G-Cubed, 25, e2024GC011739.
Toyokuni, G., Zhao, D. & Kurata, K. (2022) JGR Solid Earth, 127, e2022JB024298.
Zhao, D., Fujisawa, M. & Toyokuni, G. (2017) Sci. Rep., 7, 44487.