Contingency Plan

Expedition 358 drilling sequence

  • BOP setting on the ocean bottom
  • Ultra deep drilling
  • Sample return from plate boundary
  • Onboard analysis

Chikyu will enter the port of Shimizu and end the IODP Expedition 358 on March 31, 2019.


Having ended drilling at Site C0002, we have decided to carry out contingency plans for riser drilling at other sites in the Nankai Trough.


Today we have to inform that we will be unable to reach our primary target, the plate boundary fault, during the Expedition 358. The geological formation at the drill site has turned out to be more challenging to drill than we thought. We have attempted practically the best way to reach the target zone, based on long and deep discussion with the international and domestic scientists and drilling engineers, but have been unable to overcome the series of challenges.
Nevertheless, drilling operation continues to deepen the hole and, as of this writing, we have reached 3262.5 mbsf beyond the record depth of scientific ocean drilling. The shipboard scientists are working on geophysical data and cuttings samples to tackle the mechanism of seismogenesis.
Thank you very much for your patience and continuous support for Chikyu

◆2018/12/3 Broke our own world record for the deepest scientific ocean drilling (3058.5 m below seafloor) on 3 December!

Expedition 358 overview

Nankai Trough Seismogenic Zone Experiment drilling expeditions have reached the final phase this October. About 11 years have passed since the first IODP (International Ocean Discovery Program) operation by D/V Chikyu cruise in September 2007. So far D/V Chikyu has completed 15 expeditions, 68 holes, and drilled a total length of more than 34 km. IODP Site C0002 has been attempted three times before (IODP Exps. 326, 338 and 348), in steps, finally reaching 3,058.5 mbsf (meters below sea floor) during 348. The objectives of IODP Expedition 358 are to penetrate toward 5,300 m, to cross the high-amplitude seismic reflector where the main plate boundary fault is believed to exist, crossing by Real-Time M-LWD (Measurement-Logging While Drilling) and WL (Wire Line) operation, monitor mud gas and cuttings, and limited core sampling of the ultra-deep fault zone. These operations are extremely difficult tasks never before achieved due to the fragile geological formation comprising the accretionary prism, and factors including the powerful Kuroshio current, location subject to typhoon approaches, and also affected by the passage of multiple cold fronts during the Winter months. This expedition is the culmination of over 20 years of planning and 11 years of IODP NanTroSEIZE drilling efforts to reach the plate interface fault system at seismogenic/slow slip depths.
More details available here.
  • Completed Expeditions
  • 2007
  • 2009
  • 2010
  • 2012
  • 2013
  • 2016
  • 2018