IODP Expedition 386 “Japan Trench Paleoseismology”: Mission Specific Platform Giant Piston Coring to track past megathrust earthquakes and their consequences in a deep-sea subduction trench.
Résumé
International Ocean Discovery Program (IODP) Expedition 386, Japan Trench Paleoseismology
(offshore period: 13 April to 1 June 2021; Onshore Science Party: 14 February to 14 March 2022)
was designed to test the concept of submarine paleoseismology in the Japan Trench, the area
where the last, and globally only one out of four instrumentally-recorded, giant (i.e. magnitude 9
class) earthquake occurred back in 2011. “Submarine paleoseismology” is a promising approach to
investigate deposits from the deep sea, where earthquakes leave traces preserved in the
stratigraphic succession, to reconstruct the long-term history of earthquakes and to deliver
observational data that help to reduce uncertainties in seismic hazard assessment for long return
periods. This expedition marks the first time, giant piston coring (GPC) was used in IODP, and also
the first time, partner IODP implementing organizations cooperated in jointly implementing a
mission-specific platform expedition.
We successfully collected 29 GPCs at 15 sites (1 to 3 holes each; total core recovery 832 meters),
recovering 20 to 40-meter-long, continuous, upper Pleistocene to Holocene stratigraphic
successions of 11 individual trench-fill basins along an axis-parallel transect from 36°N – 40.4°N, at
water depth between 7445-8023 m below sea level. These offshore expedition achievements
reveal the first high-temporal and high spatial resolution investigation and sampling of a hadal
oceanic trench, that form the deepest and least explored environments on our plant.
The cores are currently being examined by multimethod applications to characterize and date
hadal trench sediments and extreme event deposits, for which the detailed sedimentological,
physical and (bio-)geochemical features, stratigraphic expressions and spatiotemporal distribution
will be analyzed for proxy evidence of giant earthquakes and (bio-)geochemical cycling in deep sea
sediments. Initial preliminary results presented in this EGU presentation reveal event-stratigraphic
successions comprising several 10s of potentially giant-earthquake related event beds, revealing a fascinating record that will unravel the earthquake history of the different along-strike segments
that is 10–100 times longer than currently available information. Post-Expedition research projects
further analyzing these initial IODP data sets will (i) enable statistically robust assessment of the
recurrence patterns of giant earthquakes, there while advancing our understanding of earthquakeinduced
geohazards along subduction zones and (ii) provide new constraints on sediment and
carbon flux of event-triggered sediment mobilization to a deep-sea trench and its influence on the
hadal environment.
IODP Expedition 386 Science Party: Piero Bellanova; Morgane Brunet; Zhirong Cai; Antonio
Cattaneo; Tae Soo Chang; Kanhsi Hsiung; Takashi Ishizawa; Takuya Itaki; Kana Jitsuno; Joel
Johnson; Toshiya Kanamatsu; Myra Keep; Arata Kioka; Christian Maerz; Cecilia McHugh; Aaron
Micallef; Luo Min; Dhananjai Pandey; Jean Noel Proust; Troy Rasbury; Natascha Riedinger; Rui Bao;
Yasufumi Satoguchi; Derek Sawyer; Chloe Seibert; Maxwell Silver; Susanne Straub; Joonas
Virtasalo; Yonghong Wang; Ting-Wei Wu; Sarah Zellers
