Articles | Volume 502
https://doi.org/10.5194/piodp-502-1-2026
https://doi.org/10.5194/piodp-502-1-2026
Scientific prospectus
 | 
05 Feb 2026
Scientific prospectus |  | 05 Feb 2026

IODP3 Expedition 502 “Impact of Petit-Spot Magmatism on Subduction Zone Seismicity and Global Geochemical Cycles” Scientific Prospectus

Asuka Yamaguchi, Hiroko Kitajima, and Natsumi Okutsu

Cited articles

Akizawa, N., Hirano, N., Machida, S., Tamura, C., Kaneko, J., Iwano, H., Danhara, T., and Hirata, T.: A direct evidence for disturbance of whole sediment layer in the subducting Pacific plate by petit-spot magma–water/sediment interaction, Mar. Geol., 444, 106712, https://doi.org/10.1016/j.margeo.2021.106712, 2022. 
Fujie, G., Kodaira, S., Nakamura, Y., Morgan, J. P., Dannowski, A., Thorwart, M., Grevemeyer, I., and Miura, S.: Spatial variations of incoming sediments at the northeastern Japan arc and their implications for megathrust earthquakes, Geology, 48, 614–619, https://doi.org/10.1130/G46757.1, 2020. 
Fujiwara, T., Hirano, N., Abe, N., and Takizawa, K.: Subsurface structure of the “petit-spot” volcanoes on the northwestern Pacific Plate, Geophys. Res. Lett., 34, L13305, https://doi.org/10.1029/2007GL030439, 2007. 
Hirano, N.: Petit-spot volcanism: a new type of volcanic zone discovered near a trench, Geochem. J., 45, 157–167, https://doi.org/10.2343/geochemj.1.0111, 2011. 
Hirano, N. and Machida, S.: The mantle structure below petit-spot volcanoes, Nat. Commun., 3, 110, https://doi.org/10.1038/s43247-022-00438-1, 2022. 
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Short summary
IODP3 Expedition 502 will drill the outer-rise area of the Japan Trench, where the sediments above the acoustic basement are thin. The thin sediments are hypothesized to be caused by basalt intrusions or lava flows related to petit-spot magmatism, a type of volcanic activity caused by the bending of the incoming plate near the trench. Our goal is to determine whether petit-spot magmatism is more widespread than previously thought and to understand its role in the Earth's systems.
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