Site summary

Hole C0002C–riserless observatory

Priority: Contingency: Chikyu Expedition 326 (NanTroSEIZE Stage 3: plate boundary deep riser: top hole engineering)
Position: 33°18.02′N, 136°38.18′E
Water depth (m): 1936
Target drilling depth (mbsf): 1000
Approved maximum penetration (mbsf): 1400
Survey coverage: CDEX 2006 3-D MCS; extensive survey data outlined in Proposal 603C-Full:
• 3-D In-line 2529
• 3-D Cross-line 6225
Objective (see text for full details): Case riserless hole to 1000 mbsf in preparation for future permanent observatory installation
Drilling, coring, and downhole measurement program: • Set 20 inch casing to 36 mbsf
• Drill 12-1/4 inch hole to 1000 mbsf
• Set 9-5/8 inch casing to 1000 mbsf
• MWD, cement-bond log
Anticipated lithology: 0–150 mbsf: Kumano forearc basin sediments
150–910 mbsf: lower sediments
910–1400 mbsf: accretionary prism