Anomalous changes of deep-sea chemical environments and microbial communities induced by the M9.0 Tohoku Earthquake

We investigated the rapid impacts of the M9.0 Tohoku Earthquake on the deep-sea environment 36 days after the event. The light transmission anomaly became atypically greater and more extensive near the trench axis owing to the turbulent diffusion of fresh seafloor sediment, coordinated with potential seafloor displacement. In addition to the chemical influx associated with sediment diffusion, an unusual influx of fluid with 13C-enriched methane into the deep-sea water from the deep sub-seafloor reservoirs occurred, possibly triggered by the earthquake and its aftershocks. The biomass and phylotype composition of the deep-sea microbial communities also responded rapidly to the event. We examined the post-earthquake deep-sea chemical environments and the development of the microbial community.